The ToK and Unification of Psych

The Tree of Knowledge System and the TheoreticalUnification of Psychology

Gregg HenriquesUniversity of Pennsylvania

The outline for theoretically unified psychology is offered. A new epistemologicalsystem is used to provide a unique vantage point to examine how psychological scienceexists in relationship to the other sciences. This new view suggests that psychology canbe thought of as existing between the central insights of B. F. Skinner and SigmundFreud. Specifically, Skinner’s fundamental insight is merged with cognitive neuro-science to understand how mind emerges out of life. This conception is then joinedwith Freud’s fundamental insight to understand the evolutionary changes in mind thatgave rise to human culture. By linking life to mind from the bottom and mind to culturefrom the top, psychology is effectively boxed in between biology and the socialsciences.

We have a surfeit of facts. What we do not have, andmost of us in the quiet of our nights know it, is anoverarching conception of context in which we can putthese facts and, having done so, the truth then stands achance of emerging. (S. B. Sarason, 1989, p. 279)

It is well known that there currently is nounified theory of psychology. There is so muchambiguity and so many theoretical schisms thatstudents are taught to be skeptical of any unifiedapproaches. In his popular book How to ThinkStraight About Psychology, Keith Stanovich(2001) characterized the difficulty in theoreti-cally uniting the field as follows:

The diversity of psychology guarantees that the task oftheoretical unification will be immensely difficult. In-deed, many in psychology would argue that such aunification is impossible. Others, however, are search-ing for greater unification within the field . . . . No mat-ter what their position on the issue, all psychologistsagree that theoretical unification will be extremelydifficult and that such a unification will occur years inthe future, if it is to occur at all [italics added]. (p. 3)

Stanovich further commented that many whofirst learn the subject matter are disappointed todiscover the absence of a unifying perspective.However, he ultimately minimized the prob-lems associated with disunity and suggestedthat the diversity of approaches in psychology isa strength.

Although I applaud Stanovich’s pluralisticapproach from a political perspective, I take adifferent view on the issue of theoretical dis-unity. My view is similar to the one held byArthur Staats (1983), who has articulated theproblems associated with disunity as clearly asanyone. He observed:

Psychology has so many unrelated elements of knowl-edge with so much mutual discreditation, inconsis-tency, redundancy, and controversy that abstractinggeneral meaning is a great problem. There is a crisis,moreover, because the disunification feeds on itselfand, left unchanged, will continue to grow. (Staats,1991, p. 899)

Others have expressed similar concerns. PaulMeehl (1978/1992) noted:

It is simply a sad fact that in soft psychology theoriesrise and decline, come and go, more as a function ofbaffled boredom than anything else; and the enterpriseshows a disturbing absence of that cumulative charac-ter that is so impressive in disciplines like astronomy,molecular biology and genetics. (p. 524)

As suggested by Meehl’s quote, the value ofa unified perspective is seen clearly in our sisterdiscipline, biology. In the 1940s, the modernsynthesis was forged when evolutionary theory

I would like to thank Kenneth Ford, David Geary, PaulGrant, Joe Moldover, and Russell Ramsey for their helpfulcomments on earlier versions of this article. I would alsolike to thank those individuals who contributed to the fruit-ful exchange on philosophical issues pertaining to cognitiveand behavioral science on the Society for Science andClinical Psychology Listserv.

Correspondence concerning this article should be ad-dressed to Gregg Henriques, Department of Psychiatry,University of Pennsylvania, 2029 Science Center, 3535Market Street, Philadelphia, Pennsylvania 19104. E-mail:[email protected]

Review of General Psychology Copyright 2003 by the Educational Publishing Foundation2003, Vol. 7, No. 2, 150–182 1089-2680/03/$12.00 DOI: 10.1037/1089-2680.7.2.150

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merged with the science of genetics (Mayr &Provine, 1998). Biologists from a wide varietyof subspecialties such as evolutionary biology,biochemistry, population genetics, cytology,botany, and ecology came together and agreedthat the science of life could be theoreticallyunited. Natural selection operating on geneticcombinations through time became the centralorganizing principle that provided the causalexplanatory framework for observed biologicalcomplexity. This unification had a tremendousimpact on the capacity of the field to organizeitself. A shared mission, a shared language, anda shared conceptual foundation have allowedfor much greater consistency, novelty of discov-ery, and accumulation of knowledge. The cen-tral role biological theory played in these devel-opments is captured by Theodosius Dobzhan-sky’s (1973) famous quote, “Nothing in biologymakes sense except in the light of evolution.” Atwist on this quote might capture the currentstate of affairs in psychology: “Nothing in psy-chology makes sense.”

Recent Proposals on Unification

But is the theoretical unification of psychol-ogy a genuine possibility? Despite the dauntingnature of the task, there has recently been asmall but growing interest in unified approachesto the field (e.g., Gilgen, 1987; Magnusson,2000; Newell, 1990). Gregory Kimble (1996)offered an approach to unification in the neobe-haviorist tradition called “functional behavior-ism” in which he outlined five Newtonian-likeprinciples that he argued provide the frameworkfor unifying psychology. Norman Anderson(1996) offered a functional theory of cognitioncalled information integration theory that at-tempts to account for the phenomenology ofeveryday experience. Positing that thought andaction must be understood in terms of goaldirectedness, Anderson developed a functionaltheory of measurement to map human “cogni-tive algebra” and applied this framework tomany diverse areas in psychology such as psy-chophysics, person perception, judgment anddecision making, emotional reactions, and egodefenses. In contrast to both Kimble and Ander-son, who emphasize unifications from behav-ioral and cognitive perspectives, respectively,Sternberg and Grigorenko (2001) offered a“unified psychology,” which they defined as

“the multiparadigmatic, multidisciplinary, and in-tegrated study of psychological phenomenathrough converging operations” (p. 1069). Theseauthors argued that the field should be organizedaround psychological phenomena (e.g., learningor prejudice), as opposed to specific disciplines(i.e., social), particular schools of thought (i.e.,cognitivist), or single methodologies.

Staats (1963, 1996) has articulated perhapsthe most ambitious approach to unification.Called psychological behaviorism, Staats’s ap-proach explicitly attempts to build bridges bothwithin the various fields in behavioral scienceand between behaviorism and traditional psy-chology (e.g., social and personality). Staatsdescribed his work as an interlevel, interfieldtheory that cuts across the various disciplines inthe field and uses simpler phenomena to explainmore complex phenomena. Staats (1996) an-chored his model to an evolutionary biologicalaccount of emotions and articulated how ani-mals build “basic behavioral repertoires”throughout their development by learning toapproach positive emotional stimuli and avoidnegative emotional stimuli. Staats used thismodel as a building block for more complexmodels of human cognitive phenomena, such aslanguage, and thus linked behavioral theorywith higher cognitive processes. Like Ander-son, he has applied his framework to manydiverse areas.

A Problem of Epistemology

These frameworks seek to provide a solutionto psychology’s increasing problem of disunityand should be applauded as such. However,despite the laudable ambitions, I believe that thecurrent approaches are not sufficient becausethey fail to provide a broad, clear epistemolog-ical framework that sets the stage for definingthe discipline and coherently unifying the majorparadigms in the field. When one asks basicquestions of these proposals such as “How arelife, mind, culture, and behavior defined?” or“How is psychology specifically differentiatedfrom biology from below and the social sci-ences from above?” or “How are the key in-sights from neuroscience, psychodynamic the-ory, evolutionary theory and genetics, behav-ioral science, cognitive science, systems theory,and social constructivist perspectives retainedand integrated into a coherent whole?” answers

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are not readily forthcoming. Instead, these per-spectives either struggle with or remain silenton these big questions.

According to this analysis, then, current uni-fied approaches have failed not because theyhave been too general but because they have notbeen general enough. What is needed is a meta-theoretical framework that crisply defines thesubject matter of psychology, demonstrates howpsychology exists in relationship to the othersciences, and allows one to systematically inte-grate the key insights from the major perspec-tives in a manner that results in cumulativeknowledge. Metaphorically, each “key insight”can be viewed as a piece of the larger puzzle.And, as with completing a puzzle, the morepieces that are filled in, the clearer the overallpicture. Furthermore, as the puzzle is com-pleted, it will become increasingly clear as towhich theoretical pieces do not fit into the over-arching scheme.

In fitting the pieces together, what have tra-ditionally been “either–or” epistemologicalsplits become “both-and-neither” answers. Theargument here is that the schisms between cog-nitive and behavioral science perspectives, dis-tal/nature and proximal/nurture perspectives,psychodynamic and behavioral therapeutic per-spectives, and constructivist and empiricistepistemological perspectives are the conse-quences of incomplete, partially correct knowl-edge systems being defined against one anotherin a manner that is more political than scientific.These fragmented, politically antagonistic mini-epistemologies create a buzzing, confusingmass of information that prevents cumulativeunderstanding. Some basic epistemologicalagreement about the phenomena under exami-nation is needed prior to healthy scientific dis-agreement about particular issues. Without suchprior agreements, opponents cannot agree onthe questions to ask, which greatly limits thevalue of answers offered by the empirical pro-cess. In fact, several have argued that psychol-ogy is a “would be” science because, unlike the“true” sciences of physics and biology, it hasbeen unable to generate a consensually agreedupon conceptual framework that guides its sci-entific endeavors (Staats, 1999).

One needs to look no farther than the ideas ofB. F. Skinner and Sigmund Freud, perhaps thetwo greatest figures in psychology, to see thatmarkedly contrasting views have been taken.

Each proposed a grand theory that has had atremendous impact on the field. Yet, the twoperspectives appear to be wholly incompatible.Skinner pejoratively dismissed “mentalistic”approaches and placed the focus on the causalrole of the environment in the selection of be-havioral responses. He also took an extremefact-based approach to science and even ques-tioned the need for deep theoretical constructsin psychology. The foundational database forhis behavioral selection paradigm was the be-havior of animals in the laboratory. Conversely,Freud’s psychoanalytic paradigm was unabash-edly mentalistic in nature. Stemming from ob-servations of troubled humans free-associatingon a couch, Freud wove together powerful in-sights with wild speculations and formulated anelaborate but ultimately unfalsifiable grand the-ory of the human mind. Of course, both Freudand Skinner are much maligned in opposingcircles, and the vast majority of psychologistsview each of their respective paradigms as in-complete and at least partially incorrect. Yet,both Skinner and Freud remain pillars of thefield, and there is not currently a way to blendthe insights of the two together in a coherentfashion.

According to this analysis and in direct con-trast to those who argue that unification is im-possible (e.g., Koch, 1993; Messer & Winokur,1980), a unified approach can coherently unitethe ideas of Skinner and Freud using the sameoverarching system, one that clearly spells outthe errors and inconsistencies in each paradigmwhile retaining the key theoretical insights fromboth perspectives. Of course, students of psy-chology are not offered such a system. Instead,as highlighted by the quotation from Stanovichoffered earlier, students are simply taught aboutthe diversity of ideas and left to their owndevices to sort out the issues. The current pro-posal seeks to change this status quo. The out-line of a system is offered that I propose alignsthe central insights of Skinner and Freud bothwith one another and with science at large.More specifically, I show how the science ofpsychology can be thought of as existing be-tween the central insights of Skinner and Freud.In putting these pieces of the puzzle together, Ioffer a way to clearly define the field and pro-vide a metatheoretical framework that can in-corporate the major theoretical perspectives intoa coherent whole.

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The Tree of Knowledge System: AProposal for a Universally Agreed UponRepresentation of Scientific Knowledge

The advertisement that one could coherentlyunite the ideas of Skinner and Freud in a mannerthat provides a unified approach must be ac-knowledged to be a particularly audaciousclaim. The proposition is based on a new systemof knowledge called the Tree of Knowledge(ToK) System. The ToK System is formallypresented in Figure 1.

In his seminal work Consilience: The Unityof Knowledge, Edward O. Wilson (1998) pre-sented a grand vision of how all knowledge,from quantum mechanics to culture, might beorganized into a single overarching framework.The ToK System is constructed in the traditionof consilience, and, by offering a visuospatialrepresentation of the entire system, it consider-ably advances Wilson’s formulation. The tre-mendous advantage of the visuospatial Gestaltis that it simultaneous defines extremely broadconcepts (e.g., life and mind) and defines howthey exist in relationship to one another in asingle, coherent knowledge system. The systemof interlocking definitions ultimately providesthe potential framework for a universally sharedconceptual foundation and definitional systemfrom which scientists from all disciplines couldwork. To more fully understand the message theToK System communicates, it is useful tobriefly review the evolution of complexity astold by modern science.

The Evolution of Complexity From BigBang to Present

In accordance with modern cosmology, theToK System assumes that the universe began asan energy singularity (Gribbin, 1998). Approx-imately 15 billion years ago, there was a chainreaction in the energy singularity called the“Big Bang,” in which the pure energy quantabegan to freeze into chunks of matter, calledfermions (Ferris, 1997). Fermions are the fun-damental units of matter that come in two types,quarks and leptons, and ultimately interact toform all of the matter in the universe (Greene,1999). The Big Bang also generated the contin-uums of space and time (Hawking, 1998). Asthe universe expanded and cooled, subatomicparticles formed into atomic systems. Large col-

lections of gases condensed and formed intostars and galaxies. A wide variety of energy–matter environments emerged, which in turnresulted in the formation of a variety of differenttypes of atoms.

In particular environments that are neithertoo hot nor too cold, atoms link up through theprocess of covalent bonding and create increas-ingly complex chemical systems. The chemicalsystems on the Earth’s surface 4 billion yearsago exhibited a wide variety of algorithmicallycomplex behaviors (Maden, 1995), and one par-ticular class of these behaviors was self-repli-cation (Lifson, 1997). Through the process ofreplication, variation, and selection, these self-replicating chemical systems became increas-ingly complex and eventually formed into hugestrands of ribonucleic acid (Maynard-Smith &Szathmary, 1999). Over the next several hun-dred million years, these self-replicating chem-ical machines transformed into prokaryotes(primitive cells that lack a nucleus), then eu-karyotes (cells with a nucleus), and finally intolarge-scale, multicellular organisms (Dennett,1995). This period from 4 billion years to 700million years ago saw the evolution of lifethrough natural selection operating on geneticsystems.

Between approximately 640 and 550 millionyears ago, a new type of multicellular creatureemerged, called animals (Gould, 1989). Ani-mals are unique in that they are multicellularorganisms that move around their environment(Boakes, 1984). The capacity for movementresulted in the evolution of a computationalcontrol center that measures the animal’s rela-tionship to its environment and moves the ani-mal toward beneficial environments and awayfrom harmful environments (Hoyle, 1964). Thiscomputational control center is, of course, thenervous system. The nervous system representsa fundamental shift in complexity because thebehavior of animals is not fully restricted to theunfolding of the genetic program encoded in thedeoxyribonucleic structure. Instead, animalsgenerate new behavioral outputs in response tonovel environmental stimuli. The period from640 million years ago to 5 million years ago sawthe evolution of the animal mind.

The period from 5 million years ago throughtoday saw the emergence of culture, which oc-curred for one particular animal, the human


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animal.1 Bipedalism had clearly emerged by 3.5million years ago (Leaky & Lewin, 1992), andby 1.4 million years ago Homo erectus, one ofour hominid ancestors, was making complicatedhand axes (Mithen, 1996). The evolution ofhuman language is generally thought to haveoccurred anywhere between 2 millionand 50,000 years ago (Bickerton, 1995; Lieber-man, 1998; Pinker, 1994). This period is asso-ciated with substantial growth of the corticalstructures, as well as changes in throat struc-tures associated with language. This time periodis also associated with the emergence of modernhumans.

Between 60,000 and 40,000 years ago, therewas an explosion of cultural artifacts, such ascarved statues, artwork in caves, and burialswith ornamentation (Bahn, 1996). Modern hu-mans began to appear in landscapes all over theworld (Stringer & McKie, 1997). And the paceof change only accelerated. Agriculture ap-peared approximately 12,000 years ago, settingthe stage for large-scale civilizations (Bro-nowski, 1974). Systems of belief emerged thatcoordinated the behaviors of huge populationsof people. These belief systems branched intodifferent domains such as religion, law, mathe-matics, and philosophy. Such systems of beliefcan be considered justification systems, in thatthey provide a framework for which actions arelegitimate and which actions are not. The ToKSystem suggests that science is a particularbranch in the evolution of justification systemsbuilt on the value of accuracy. The right side ofthe ToK System depicts how science emergedout of culture and functions to mathematicallymap complexity and change (Hawking, 1998;Wilson, 1998).

Presenting the Familiar in an UnfamiliarWay

The ToK System is essentially a picture ofthe evolution of complexity, as presentlymapped out by science. The metaphor of thetree is used to illustrate how various branches ofcomplexity emerged from more basic begin-nings. The ToK System is unique in that itshows how scientific models of emergent com-plexity exist in relationship to one another in anincredibly parsimonious way. Returning to thepuzzle metaphor, the ToK System provides away to frame the puzzle of scientific knowledge

and observe how scientific theories exist in re-lationship to one another on the dimensions oftime and complexity. This new and extraordi-narily broad view sets the stage for newinsights.

The most significant aspect of the ToK Sys-tem is that it presents a four-stage model in thehierarchical evolution of complexity. Eachstage corresponds to a new dimension of algo-rithmic information sparked by a complexity-building feedback loop. The first stage is theevolution of material complexity or Matter,which was sparked by the Big Bang and re-sulted in the Energy-to-Matter transformationand the beginning of time. The second stage isthe evolution of biological complexity or Life,which was sparked by natural selection operat-ing on self-replicating chemical systems. Thethird stage is the evolution of neuronal com-plexity or Mind, which I argue was sparked bythe capacity for behavioral selection emergingout of the interaction of neuronal patterns. Thefourth stage is the evolution of symbolic com-plexity or Culture, which I argue was sparkedby the capacity for justification emerging out ofhuman communication patterns.

The four-stage model of emergent complex-ity allows for a much clearer vision of thecorrespondence between stages in the evolutionof complexity and fundamental divisions in sci-ence. As depicted and is generally well known,the physical sciences correspond to the materiallayer of complexity and the biological sciencescorrespond to the genetic layer of complexity.However, the ToK System also corresponds thepsychological sciences to the neuronal layer ofcomplexity and the social sciences to the sym-bolic layer of complexity. This basic correspon-dence goes a long way toward clarifying con-fusing issues. As mentioned earlier, a unifiedtheory of psychology must provide clear con-ceptual definitions of large concepts. Table 1offers a four-category conception of the uni-verse of scientific knowledge that consists offour fundamental levels of complexity, exis-tence, and computation and four fundamental

1 Several authors have suggested that other animals pos-sess culture (e.g., Bonner, 1980; Wrangham & McGrew,1994). Culture is defined here in terms of shared justifica-tion systems based on symbolic language (discussed inmore detail later). Using this definition, it is argued that onlyhumans have culture.


classes of science, objects, and behavior. Whencombined with the ToK System, Table 1 pro-vides a framework for the conceptual defini-tions proposed here.

The ToK System further suggests that thefour fundamental levels of complexity are eachassociated with a theoretical joint point. A the-oretical joint point can be defined as a causalexplanatory framework that accounts for theemergence of one of the four fundamental levelsof complexity. Thus, according to the ToK Sys-tem, the Big Bang is the first joint point, be-cause it provides the conceptual framework forMatter emerging out of Energy. Natural selec-tion operating on genetic combinations acrossthe generations is the second theoretical jointpoint and provides the framework for Lifeemerging out of Matter. Both of these theoriesare well known and well established in theirrespective scientific disciplines. It should bestated that the ToK System is dependent on thevalidity of these two grand theories and wouldbe invalidated in the unlikely event that eitherone of these theories were demonstrated to beinaccurate. Some may question whether itmakes sense to offer a theory of psychology thatis ultimately dependent on ideas that, at firstglance, appear so remote from the subject mat-ter at hand (particularly the Big Bang). Thereason is that the ToK System functions as asystem, and it derives much of its heuristicutility and overall explanatory power from thesymmetry and parallelism in its depiction. Ifthat symmetry and parallelism is shown to bewrong, the definitional system (or at least verykey elements of it) on which it is built collapses.

If the Big Bang and the modern synthesisrepresent the first two joint points, what aboutthe third and fourth theoretical joint points?There is not currently a well-demarcated Life-to-Mind joint point. Even less clear is the the-oretical joint point separating Mind and Culture.

It is here that the ToK System brings conceptualclarity to previously confusing issues. To jumpahead to the conclusion, I argue that the ToKSystem shows why Skinner’s ideas, when com-bined with cognitive neuroscience, provide theframework for the Life-to-Mind joint point andwhy Freud’s ideas, when anchored to a coherentmodel of the nonverbal mind, provide theframework for the Mind-to-Culture joint point.Together, these two theoretical joint points “boxin” psychology and provide a unified theoreticalframework for the field. I turn first to Skinnerianpsychology.

Critique of Skinnerian Psychology

Skinner’s behavioral selection or operant par-adigm is one of the most misunderstood sets ofideas in psychology (Catania & Harnard, 1988).This is particularly unfortunate because Skin-ner’s ideas offer a wonderfully elegant way tounderstand the evolution of behavioral com-plexity through an animal’s lifetime. In addi-tion, Skinner’s ideas are, contrary to the opinionof many, quite consistent with evolutionary the-ory, ethology, neurophysiology, and genetics.And there is nothing about the concept of be-havioral selection per se that prevents it frombeing integrated with a cognitive neuroscienceperspective. Yet, integration has not beenachieved. Why?

Ironically, and despite his brilliance, Skinnerhimself is as much to blame as anyone. First,Skinner incorrectly equated his behavioral se-lection paradigm with a fatally flawed episte-mological system that mistakenly construed thenature of the scientific enterprise. Observation-ally based description and control formed thecornerstone of his philosophy of science, and allelse was deemed extraneous (Skinner, 1950).Yet, the ultimate goal of pure science is not tocontrol behavior, as Skinner incorrectly argued.

Table 1Category Grid

Level ofcomplexity

Class ofscience

Level ofexistence

Class ofobjects

Level ofcomputation

Class ofbehavior

Culture Social Self-aware Human Symbolic SociolinguisticMind Psychological Mental Animal Neuronal NeuropsychologicalLife Biological Animate Living Genetic BiogeneticMatter Physical Inanimate Material Quantum Physicochemical

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Instead, the fundamental task of pure science isto develop mathematical models of complexityand change (Hawking, 1998; Wilson, 1998).

A second reason Skinner is to blame is that henever provided legitimate justification for hisrefusal to accept a neuro-information-process-ing view of the nervous system. Skinner cer-tainly never explained why the nervous systemcould not be an information-processing system,nor did he ever explain why such a system couldnot have evolved. Instead, Skinner’s primaryargument was that it was unnecessary and thusunhelpful to view the nervous system as aninformation-processing system. But given thesuccess of cognitive science, Skinner’s claimswere more likely a function of the fact thatcognitive science challenged his radical behav-ioral epistemology rather than being unhelpfulin any objective sense.

The third and most important problem withSkinner’s system is that he never effectivelydefined either mind or behavior. Although heeschewed the mental versus physical distinc-tion, Skinner repeatedly insisted that “privateevents” such as a “toothache” could be thesubject of scientific inquiry. In Verbal Behavior(1957), he equated “thinking” with “behaving.”But experiencing a “toothache” and “thinking”are clearly different kinds of behavior thanscratching one’s nose, and simply defining themall as “physical behavior” sidesteps this obvi-ously complicated issue. It is fairly easy tounderstand how the biomechanical contractionsof various muscle sequences result in observ-able arm movements. Yet, it is not so easy tounderstand how the behavior of neurons givesrise to thinking and feeling. The difference isnot merely in the vantage point of the behav-iorist, as Skinner’s “overt” versus “covert” dis-tinction of behavior might lead one to believe.Instead, the question of specifically how thebehavior of the brain results in thoughts andfeelings is ignored by Skinner’s epistemologicalsystem. Contrasting Skinner’s avoidance of thisissue, the question of how the behavior of thebrain gives rise to thoughts and feelings is oneof the central questions of cognitive neuro-science (Crick, 1994; Gazzaniga, 1995).

Skinner also failed to effectively define theterm behavior. He readily acknowledged thatbehavior is not easily defined, commenting that“there is no essence of behavior” (Skinner,1988b, p. 469), although this was not a signif-

icant concern for him. A problem arises, how-ever, because the term behavior is used incon-sistently. Sometimes the term is used in a gen-eral sense, such as “movements that generatemeasurable effects.” Other times it is used in aspecific sense, such as “change that can beunderstood as the function of the operant.” Thisvariation in usage is problematic, because itresults in behavior being used in mutually ex-clusive ways. For example, sometimes the termis used to connect what psychologists study towhat other “real” scientists study, as in “unlikethose Freudian folks, we are a real science be-cause we study and measure behavior.” Yet,sometimes the term is used in precisely theopposite manner. That is, the term is used todifferentiate what psychologists study fromwhat other scientists study, as in “psychology isthe science of behavior,” which is supposedlydifferent from what biologists study. Thus, thesame term, behavior, is used to justify connec-tion with other sciences in some circumstancesand used to justify differentiation from othersciences in other instances. If the same term canbe used for two mutually exclusive purposes,there is a problem with it.

A bottom-up perspective clarifies the issuesfurther. The most general definition of behav-ior is change in an object–field relationship,which can be algorithmically represented as(X)(Xo)t1 � (X)(Xo)t2, where X is the object,Xo is the field (not X) and t is time. This isimportant because it highlights that all sciencesare sciences of behavior. Physics is the scienceof the behavior of objects in general. Particlephysicists study the behavior of very small ob-jects (e.g., fermions) using quantum theory, andcosmologists study the behavior of very largeobjects (e.g., galaxies) using the theory of rela-tivity (Greene, 1999). If it is agreed that phys-icists study the behavior of objects in general,then it logically follows that other scientistsstudy the behavior of certain objects in partic-ular. Chemists study the behavior of molecularobjects; biologists study the behavior of livingobjects. This analysis highlights that there areobviously significant problems with definingpsychology as “the science of behavior.” It isnot the fact that animals behave that makesthem unique; it is that they behave so differentlyfrom other objects. The key then becomes de-fining the subset of behaviors that psychologistsstudy.


Behavioral Investment Theory as theLife-to-Mind Joint Point

Specifying the types of behaviors that psy-chologists study and why these are legitimatelydefined variables is an immensely important butobviously confusing issue. Much of this confu-sion stems from complicated epistemologicalissues and the schism between cognitive andbehavioral science. I submit here that the con-cept of behavioral investment provides theframework for uniting cognitive and behavioralscience. As such, behavioral investments andthe processes by which animals make them pro-vide a reasonable conception for the subjectmatter of psychological science. To understandwhy the subset of behavioral investments ofanimals provides the appropriate demarcationbetween psychology and biology, it is useful tomore closely analyze the joint point betweenbiology and chemistry.

The Modern Synthesis as theMatter-to-Life Joint Point

The modern synthesis resulted from themerger of the selection science of evolutionwith the information science of genetics andprovided the framework to differentiate biologyfrom chemistry (e.g., Maynard-Smith & Szath-mary, 1999). George Williams (1966) summedup the issues as follows:

The acceptance of this account of the origin of lifeimplies an acceptance of the key position of the con-cept of adaptation as at least an abstract criterionwhereby life may be defined and recognized. We aredealing with life when we are forced to invoke naturalselection to achieve a complete explanation of an ob-served system. In this sense the principles of chemistryand physics are not enough. At the least one additionalpostulate of natural selection and its consequence, ad-aptation, are needed. (p. 5)

Richard Dawkins (1999) similarly describedhow “living matter introduces a whole new setof rungs to the ladder of complexity” [italicsadded] (p. 113) through natural selection oper-ating on genetic combinations across the gener-ations. Although genes are coordinated popula-tions of molecules, individual molecules are not“small” genes. Genes are irreducible points ofcomplexity and can be conceptualized as digitsof biochemical information. In this light, biol-ogy can be thought of as the study of genetic

language generated by the complexity-buildingfeedback loop of natural selection. Utilizing theparallelism suggested by the ToK System, thequestion arises that if Life can be conceptual-ized as a fundamentally irreducible layer ofemergent complexity generated by a feedbackloop of variation, selection, and retention, canwe consider Mind similarly? I argue yes. In-deed, this is very nearly the way B. F. Skinnerconceptualized it.

Mind and the Behavior of theAnimal-as-a-Whole

Although Skinner never effectively definedbehavior, he did offer a unique and powerfulway to conceptualize it. Skinner frequently usedthe phrase “the behavior of the organism-as-a-whole” (e.g., Skinner, 1990) to define the sub-ject matter of his operant paradigm. Given theimportance of precise definitions, it is importantto note that Skinner’s phrase “behavior of theorganism-as-a-whole” is slightly unfortunatebecause it is overinclusive. Plants are organismsand one could argue that, in some respects, treesbehave “as-a-whole,” but the behavior of treesis not of much interest to a psychologist. It is thebehavior of animals with a nervous system thatis of interest.

What Skinner’s analyses (along with manyothers) demonstrated is that animals behave as awhole in a manner that produces a functionaleffect on the animal–environment relationship.Moreover, Skinner meticulously documentedhow the behavior of the animal-as-a-whole wasinfluenced depending on the functional effectsor consequences the behavior produced. Skin-ner termed these functional environmental ef-fects that influence the likelihood of future be-haviors operants, and he most eloquently artic-ulated how animal behaviors that producecertain effects are selected for (i.e., are rein-forced), whereas behaviors that failed to pro-duce certain effects are selected against (i.e., areextinguished).

Skinner’s brilliance was that he realized thatthe ontogenetic evolution of behavioral com-plexity could be conceptually modeled in pre-cisely the manner in which Darwin explainedthe evolution of biological complexity (Skinner,1966, 1981). Variation and selection by conse-quences provided the theoretical framework(Donahoe, Burgos, & Palmer, 1993). Thus,

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Skinner had discovered psychology’s theory ofevolution.2 Unfortunately, as Darwin lackedknowledge of genetics, Skinner never appreci-ated that an information-processing view of thenervous system provided a proximal explana-tion for his observations.3

Given the preceding discussion that it is notbehavior in general that psychologists are at-tempting to define, but a specific subset of be-havior, it is useful to suggest that the importantelement in Skinner’s oft-used phrase is not “be-havior” but the specifier “animal-as-a-whole.”Focusing on this element of the expression al-lows one to more clearly see the problem ofanimal behavior and what differentiates the be-havior of animals from that of other organisms.Animals behave as units that produce specific,predictable effects on the animal–environmentrelationship. With this clarification, it canreadily be argued that the expression “as awhole” is too banal to capture the unique ele-ment of animal behavior. Instead, I would sug-gest that coordinated singularity is preferred, asit better captures the fact that it is becauseanimals behave as coordinated singularities thattheir behavior is so unique and mysterious. Italso highlights that this is the subset of behav-iors, rather than behaviors in general, that psy-chologists should be trying to explain. Ofcourse, it is the nervous system that allowsanimals to behave as coordinated singularities.Thus, according to this analysis, and in directcontrast to Skinner’s (1950) antitheoreticalstance regarding the conceptual nervous system,psychologists need the structure of the nervoussystem and the informational concept of theneural impulse to explain how animals behave,in much the same manner that biologists needthe structure of DNA and the informationalconcept of the gene to explain the behavior oforganisms in general.

With these clarifications, we can now askhow one might connect Skinner’s behavioralselection paradigm with cognitive4 science.There is a familiar saying in the cognitive sci-ence community that the mind is what the braindoes. If the mind is what the brain does, weshould then ask, What does the brain do? Theusual answer from the cognitive scientist is thatthe brain processes information. Traditionally,this is where the radical behaviorist objects andthe break in understanding occurs. However, anevolutionary perspective provides an intriguing

and obvious but also different answer to thequestion of what the brain does. The nervoussystem evolved to coordinate the movement ofthe animal-as-a-whole (e.g., Adrian, 1935;Hoyle, 1964). The key defining elements thatdifferentiate multicellular animals from otherorganisms are the capacity for free movementand the presence of the nervous system. Thus,the information-processing component high-lighted by cognitive scientists is actually ameans to an end. Coordinated movement of theanimal as a whole is why we have nervoussystem complexity, or mind.

The phylogenetic functional base then pro-vides the framework for unification between thecognitive and behavioral positions. If cognitivescientists study the mind and the mind is whatthe brain does and what the brain does is coor-dinate the behavior of the animal-as-a-wholeand Skinner’s operant paradigm is the study ofthe behavior of the animal-as-a-whole, thenwhat has been an irresolvable schism becomestwo sides of the same coin. Behavioral sciencecan now be conceptualized as a third-personperspective that views animal behavior as infor-mation and attempts to systematically describe

2 It would be legitimate to challenge this implicationbecause the behavioral selection paradigm was in place wellbefore Skinner. For example, Edward L. Thorndike clearlyadopted a behavioral selectionist paradigm (Donahoe,1999). The argument here is that Skinner deepened andpromoted our understanding of behavioral selection morethan anyone else.

3 Of course, one could rightly point out that an importantdifference here is that Darwin did not know about genetics,whereas Skinner had exposure to the neuro-information-processing models of the brain; he simply disagreed withthem.

4 The term cognitive is a confusing term with manydifferent connotations. Sometimes the term is used in thebroad sense to refer to general neural information process-ing (e.g., Neisser, 1967; Reed, 1996), and sometimes it isused in a narrow sense, as in “cognition is different frommotivation and emotion.” I am using the term here in itsbroad sense, which includes concepts such as perception,motivation, and affect. Such processes are clearly present inanimals as well as humans (Roth & Wulliman, 2001).Adding to the overall confusion here is the fact that thesubstantial majority of cognitive psychologists study humancognition, which is, as discussed later, different in importantways from animal cognition, the most notable differencebeing symbolic information processing (e.g., Deacon,1997). Thus, there is much in the cognitive versus behav-ioral debate that is obscured by the fact that cognitivepsychologists generally focus on humans, whereas behav-iorists study and think in terms of animal behavior.


the functional relationships in the changes be-tween the animal and its environment. Cogni-tive neuroscience can be conceptualized as acomplementary first-person perspective thatviews the brain as an information processor andattempts to systematically map the changeswithin the nervous system that correspond to thechanges between the animal and its environ-ment. Causal preeminence is granted neither tochanges within the nervous system nor tochanges outside the animal. Instead, both sets ofchanges are conceptualized as sets of effectsgenerated by an unfolding wave of causalitysynonymous with time.

Given this analysis, mind equals the behaviorof the animal-as-a-whole in the sense that whatmakes the behavior of animal objects unique isthat they behave as coordinated singularitiesthat produce a systematic, functional effect onthe animal–environment relationship. Cognitiveneuroscience and cybernetics provide theframework for how the nervous system coordi-nates the behavioral expenditures of the animal-as-a-whole through the hierarchical arrange-ment of neuro-information-processing struc-tures (e.g., Geary, 1998; Powers, 1973;Pribram, 1986). Thus, just as the science of lifewas united by the selection science of evolutionwith the information science of genetics, thescience of mind is, according to the ToK Sys-tem, united by the selection science of behav-iorism with the information science of cognitiveneuroscience.

Behavioral Investment Theory

Behavioral investment theory (BIT) is a the-ory of the conceptual nervous system and aformal proposal for the Life-to-Mind theoreticaljoint point. It can also be thought of as theoutline of a unified theory of animal behavior.BIT posits that the nervous system evolved asan increasingly flexible computational systemthat computes and coordinates the behavioralexpenditure of energy of the animal-as-a-whole.Expenditure of behavioral energy is computedon an investment value system built phylo-genetically through natural selection operatingon genetic combinations and ontogeneticallythrough behavioral selection operating on neu-ral combinations (see Johnston, 1999, for com-puter simulations of precisely such formula-tions). As such, the current behavioral invest-

ments of the organism are conceptualized as theproduct of the two vectors of phylogeny andontogeny. Figure 2 offers a graphic representa-tion of these two vectors and uses the twovectors to identify the focus of various disci-plines. In such a formulation, BIT links distalcausation with proximal causation under thesame concept of behavioral investment. Withthese clarifications, the four fundamental postu-lates of BIT can be stated as follows:

1. The nervous system evolved as a compu-tational control center that coordinates thebehavior of the animal-as-a-whole (e.g.,Hoyle, 1964).

2. Genes that tended to build neurobehav-ioral selectors that expended behavioralenergy in a manner that positively covar-ied with inclusive fitness were selectedfor, and genes that failed to do so wereselected against. Thus, inherited tenden-cies toward the behavioral expenditure ofenergy are a function of ancestral inclu-sive fitness (e.g., Hamilton, 1964).

3. In ontogeny, behavioral investments thateffectively move the animal toward ani-mal–environment relationships that posi-tively covaried with ancestral inclusivefitness are selected for (i.e., are rein-forced), whereas behavioral investmentsthat fail to do so are extinguished (e.g.,Thorndike, 1905).

Figure 2. Behavioral investments as a function of the twovectors of phylogeny and ontogeny.

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4. The current behavioral investments of ananimal can be understood as a function ofthe two vectors of phylogeny and ontog-eny (Skinner, 1966; Figure 2).

As discussed earlier, unified approaches topsychology must provide a framework for con-ceptual agreement, such that the key insightsfrom various perspectives can be integrated intoa more coherent whole. As illustrated in Fig-ure 3, BIT is a proposed amalgamation of fivebroad domains of thought: evolutionary theoryand genetics, behavioral science, cognitive sci-ence, cybernetics/control theory, and neuro-science. BIT claims to be deeply consistent witheach of these domains of thought and buildsbridges between them. For example, those fa-miliar with ethological or behavioral ecologicalapproaches will likely point out that BIT closelyparallels their conception of animal behavior(e.g., Eibl-Eibesfeldt, 1989; J. R. Krebs & Da-vies, 1997; Tinbergen, 1951). Parental invest-ment theory (Trivers, 1971) and optimal forag-ing theory (e.g., Stephens & Krebs, 1986) aretwo powerful ideas that are outgrowths of a verysimilar conception of nervous system complex-ity. Dawkins (1999) spelled out a “neuro-eco-nomic” model of behavioral investment that isvery similar, if not identical, to the one offeredby BIT. In describing how genes might buildneuronal learning mechanisms, he wrote:

One way for genes to solve the problem of makingpredictions in rather unpredictable environments is to

build in the capacity for learning. Here the programmay take the form of the following instructions to thesurvival machine: “Here is a list of things defined asrewarding: sweet taste in the mouth, orgasm, mildtemperature, smiling child. And here is a list of nastythings: various sorts of pain, nausea, empty stomach,screaming child. If you should happen to do somethingthat is followed by one of the nasty things, don’t do itagain, but on the other hand, repeat anything that isfollowed by the nice things.” The advantage of this sortof programming is that it greatly cuts down the numberof detailed rules that have to be built into the originalprogram; and it is also capable of coping with changesin the environment that could not have been predictedin detail. (Dawkins, 1989, p. 57)

But evolutionary theorists are not the onlyones who have this conception of the nervoussystem. Skinner was also deeply concerned withthe evolution of behavior, and those familiarwith Skinner’s work on the evolution of operantconditioning will see that BIT has a familiarring to it (e.g., Skinner, 1984). Although Skin-ner might have objected to some of Dawkins’s“vernacular,” he would have surely agreed withthe general principle. Indeed, he voiced pre-cisely such a conception on several occasions.For example, Skinner (1974, p. 38) argued that“contingencies of survival cannot produce use-ful behavior if the environment changes sub-stantially from generation to generation, butcertain mechanisms have evolved by virtue ofwhich the individual acquires behavior appro-priate to a novel environment during its lifetime.” Unfortunately, prominent sociobiologistsand evolutionary psychologists have tended ei-ther to ignore Skinner completely or paint himin an unfavorable light (e.g., Pinker, 1997;Tooby & Cosmides, 1992; Wilson, 1975), andopportunities for merging evolutionary psychol-ogy with Skinner’s evolutionary behaviorismhave been missed. Skinner was “anti-cogni-tive,” but he was surely not “anti-biological.”As he put it, “All behavior is due to genes, somemore or less directly, the rest through the role ofgenes in producing structures which are modi-fied during the lifetime of the individual” (Skin-ner, 1988a, p. 430). In short, Skinner’s behav-ioral selection paradigm has BIT as an implicit,if not explicit, understanding.

Those in cognitive neuroscience (e.g.,Damasio, 1998; Gazzaniga, 1992), cognitivepsychology (e.g., Broadbent, 1958), and cogni-tive psychotherapy (e.g., Beck, 1999) have allvoiced a very similar conception of the nervoussystem suggested by BIT. For example, Aaron

Figure 3. Behavioral investment theory and the five majorbrain–behavior paradigms.


T. Beck argued that personality is a collectionof evolved behavioral strategies that facilitatethe solving of adaptive problems. He has furtherpointed out that much of psychopathology canbe effectively conceptualized as a mismatchbetween individuals’ inherited behavioral strat-egies and their current environmental niche(Beck, 1999). Thus, the phylogenetic by onto-genetic conception of computed behavioral in-vestment is highly consistent with the variouscognitive approaches to psychology.

A control theory or cybernetic model is alsodirectly consistent with BIT (Miller, Galanter,& Pribram, 1960). Perceptual control theory(Powers, 1973) provides a particularly powerfulmodel that explicitly builds conceptual bridgesbetween behavioral and cognitive approaches(Cziko, 2000). In this negative feedback loopmodel, animals work to reduce discrepanciesbetween current states and computationally ref-erenced goal states. A particularly fascinatingelement of the model is that it is explicitly botha neurocomputational model and a selectionistmodel. The nervous system is proposed to selectperceived consequences that move the animaltoward neuronally represented goal states. Also,in contrast to the strict environmental causationmodel imbedded in radical behavioral episte-mology, the control theory view effectively al-lows for an animal-centered point of view. Thelegitimacy of taking an animal-centered point ofview can be demonstrated with a question: “Ifthe environment can ‘select’ behavioral re-sponses, why can’t the animal?”

BIT is also consistent with developments inbehavioral neuroscience and more recent devel-opments in behavioral economics (see Staddon,2001). A behavioral neuroscience perspectivebegins with the phylogenic functional concep-tion of the nervous system held by BIT. As LordAdrian (1935), one of the founding fathers ofneurophysiology, wrote, “The chief function ofthe nervous system is to send messages whichwill make the body move effectively as awhole” (cited in Cotman & McGaugh, 1980).One of the central features emerging from thebehavioral neurosciences is the presence of twobroad biobehavioral systems, one of activation–approach and one of inhibition–avoidance (e.g.,Carver & White, 1994; Fowles, 1994). Thesetwo systems are directly consistent with BIT’sneuro-economic conception of the selection ofbehavior. The behavioral activation system mo-

bilizes the animal to approach animal–environ-ment relationships that positively covaried withpast phylogenetic–ontogenetic success, and thebehavioral inhibition system mobilizes the ani-mal to avoid those animal–environment rela-tionships that negatively covaried with phylo-genetic–ontogenetic success (see Davidson &Tomarken, 1989; Gray, 1987). Importantly, re-cent theoretical work has linked these two broadbiobehavioral systems to extraversion and neu-roticism, two of the Big Five personality factors(e.g., Watson, Wiese, Vaidya, & Tellegen,1999), resulting in a link between the two pre-viously disparate disciplines of factor-analyticpersonality theory and behavioral neuroscience.

Neural Darwinist (Edelman, 1989, 1992)models of brain development also are consistentwith the variation, selection, and retentionmodel offered by BIT. In these models, neuralnets that are used become increasingly strength-ened and interconnected, whereas neural netsthat are not die out. Likewise, recent work onselectionist approaches to adaptive neural net-works has provided promising avenues that linkbehavioral science with cognitive science andneuroscience (e.g., Donahoe et al., 1993; Tryon,1993). A further advantage of BIT is that it isconsilient with the physical sciences. As illus-trated by the ToK System, energy is the mostfundamental substance in the universe and canbe thought of as the ultimate common denomi-nator. Physicists define energy as the capacity todo work (e.g., Gribbin, 1998). In accordancewith the second law of thermodynamics, ani-mals are viewed as behavioral investors thatmust work to maintain animal–environment re-lationships conducive to survival and reproduc-tive success. The focus of BIT on efficient en-ergy expenditure links psychology with chem-istry and physics, as well as biology.

What is new about BIT is that it finds a coreof agreement and builds bridges between extanttheoretical perspectives. In so doing, a concep-tual framework is provided that demonstratesthat the splits and schisms between cognitive–behavioral and proximal–distal approaches aremirages resulting from faulty epistemologicalsystems and are more the consequence of de-fining paradigms against one another than gen-uine irreconcilability. In this new light, psychol-ogy becomes a cognitive–behavioral neuro-science (or the science of mind, brain, andbehavior of the animal-as-a-whole) built on an

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evolutionary foundation. Animal behavioral in-vestments and the neurocognitive processes as-sociated with them become the central depen-dent variables for psychological science. Andwith the ToK System, BIT provides an explicitway of understanding the Life-to-Mind jointpoint. Just as Life is the product of Darwinianevolution operating on genetic combinationsthrough the generations, Mind is the product ofSkinnerian evolution operating on neural com-binations through ontogeny.

Human Behavior Is Not Fully Explainedby Behavioral Investment Theory

I propose that most in cognitive neuro-science, behavioral science, behavioral genet-ics, ethology, and sociobiology would agreewith the broad conception offered by BIT. Cer-tainly, there will be points of disagreement andcalls for clarification. However, the more onesays, the more there is to disagree with, and Ihave intentionally used broad strokes in thepicture I have painted to facilitate the identifi-cation of points of agreement in the move to-ward greater unification.

Nonetheless, there are likely many in psy-chology who would fundamentally disagreewith the picture I have painted, at least in thesense that the picture is not complete. Person-ality and social psychologists, cultural psychol-ogists, developmental psychologists, and psy-chodynamic psychologists (to name a few)would all likely have serious reservations aboutthe adequacy of BIT as a unifying theory ofpsychology. If my hypothesis about those inpsychology who would disagree with me at thisjuncture is correct, an important point is raised.It would be primarily those who study humanbehavior who would argue that BIT is an in-complete explanatory framework. Perhaps theywould grant that BIT does provide a frameworkfor understanding the behavior of nonhumananimals. However, it is an observational factthat the behavior of humans is different fromand in many ways discontinuous with the be-havior of other animals. Thus, it is unrealistic tosuppose that the same theory could be used tounify the behavior of animals and humans. Thisobjection presents us with a conundrum, be-cause humans are animals and any unified the-ory of animal behavior must be consistent withhuman behavior.

The ToK System again helps us make senseout of potentially confusing issues. The symme-try and parallelism that allowed us to use theMatter-to-Life joint point to make sense out ofthe Life-to-Mind joint point can now be used tounderstand the Mind-to-Culture theoretical jointpoint. Life was differentiated from Matterthrough a complexity-building feedback loop(Darwinian evolution) that generated geneticcomputational systems. Likewise, Mind wasdifferentiated from Life through a complexity-building feedback loop (Skinnerian evolution)that generated neuronal computational systems.Thus, both biology and psychology were differ-entiated from the sciences beneath them by theemergence of new computational systems. Thequestion can then be asked if there is a newcomputational system associated with the de-velopment of Culture. Thankfully, an obviousanswer presents itself. Humans are capable ofsymbolic information processing in a mannerthat is fundamentally different than other ani-mals (Deacon, 1997). As such, we can use theparallelism in the ToK figure to state that just asanimals represent a subset of living objects thatcannot be fully explained by biology, humansrepresent a subset of animal objects that cannotbe fully explained by psychology.

The ToK System also suggests that to build amore complete causal explanatory frameworkfor the behavior of human objects, we need atheory of the emergence of Culture. The capac-ity for symbolic information processing (i.e.,language) is obviously a key element in thesolution to the question of what differentiateshumans from nonhuman animals. This has beensuggested by many and is surely an importantpiece of the puzzle. However, it is not enoughsimply to say that humans are verbal and otheranimals are not. Instead, we need a more preciseway of understanding the functional relation-ship between the verbal and the nonverbal mindif we are to understand that which links humanbehavior to and differentiates human behaviorfrom the behavior of nonhuman animals. And toachieve this understanding, we need to turn tothe Freudian paradigm.

Critique of Freudian Psychology

There is a large rift between Freudian andacademic psychology. As with the philosophi-cal schisms between cognitive–behavioral and


proximal–distal approaches, the split betweenacademic and Freudian psychology has had adetrimental impact on the field. Like Skinner,Freud is much to blame for the difficulties. Hewas dogmatic about his claims, and followerseither pledged allegiance to the basic proposi-tions of the psychoanalytic paradigm or becameneo-Freudians. Compounding the problem ofespousing an unchallengeable and unfalsifiablecreed was the fact that Freud was wrong aboutmany of his basic propositions. He claimed thatthere was a death instinct, and he was wrong.He argued that all drives were the derivatives oftwo motives, sex and aggression, and he waswrong. He argued that human females werebiologically destined to be jealous of humanmales, and he was wrong. To be succinct, hewas wrong in too many ways to count. But thathe was often wrong does not mean that he wasnot also often correct (Westen, 1998). If weagree that Freud made significant contributionsto our knowledge of human psychology, it mustalso be agreed that the fact that academic psy-chology pays so little attention to Freud is prob-lematic. As is often the case in therapy, the taskis to identify the dysfunctional split and tosearch for avenues that allow for a more func-tional integration.

To accomplish such an integration, it is es-sential to keep two key points in mind. First, toempathize more effectively with Freud’s systemof thought, it is necessary to remember both themethod he used to acquire data for his theoryand the cultural context in which both he and hispatients were immersed. Emerging around theturn of the century in Victorian Europe, psycho-analysis is a pluralistic term that refers to a bodyof theory, the process of analyzing behaviors interms of symbolic meanings and unconsciousmotives and conflicts, and a method of treat-ment centered on a long-term process of freeassociation and interpretation (Aiken, 1993).The sociocultural backdrop and the contextualinterrelationships among method, process, andstructure in psychoanalysis are necessary to ap-propriately frame the issues and extract generalmeaning. The absence of such a frame can leadeither to an early, blanket dismissal of Freudianthought as a collection of absurdities or to anunfortunate drowning in the metaphorical bot-tomless pit that characterizes much of psycho-analytic thinking.

Second, it is important to acknowledge thatpsychoanalysis proper is not a true scientificdiscipline and was constructed in a manner thatprevented it from becoming one. The lack ofobjectively anchored definitions and concepts,the lack of falsifiability, the frequent pro-nouncements made with excessive certainty,and, perhaps most important, a conceptualframework anchored to blatantly incorrect andoutmoded ideas regarding the nature of life andmind have all contributed to effectively renderpsychoanalytic theory proper closer to astrologythan to astronomy, at least in terms of its sci-entific status. However, this dead horse has beenbeaten repeatedly, and it is unnecessary to en-gage in yet another flogging here. Taken to-gether, these two elements mean that to repairthe dysfunctional split between Freudian psy-chology and psychological science, we shouldreturn to Freud’s observations and place them inthe context of modern scientific understanding.

Updating Freud’s Biology

The id was Freud’s core biological compo-nent of the psyche. As he summarized it, “Itcontains everything that is inherited, that ispresent at birth” (Freud, 1940/1949, p. 14). Un-fortunately, Freud was ignorant of informationscience and genetics, and his conception of evo-lution was as much Lamarckian as it was Dar-winian (Rivto, 1990). As a consequence,Freud’s conception of the id as an energy forceseeking discharge was flawed. We should notblame Freud for this, as evolutionary theory wasnot well understood at the turn of the century.However, what should have been done is thatpsychoanalysis should have been updated onthe basis of modern biology. Unfortunately,the lack of a scientific approach renders theformal psychoanalytic paradigm ineffective atself-correction.

There have been, of course, many neo-Freud-ians who have put forth conceptions of humanmotivation that are more consistent with evolu-tionary theory and genetics than classic Freud-ian drive theory (e.g., Adler, Horney, and Sul-livan). John Bowlby’s attachment theory is per-haps the most significant and successful bridgebetween psychoanalytic theory and ethology,and, more recently, several theorists have putforth eloquent presentations that explicitly at-tempt to align Freud’s conception of the id with

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modern evolutionary theory. Bailey (1987)proposed a “sociobiological id.” Slavin andKriegman (1992) suggested that psychoanalytictheorists “take a gene’s eye view” in under-standing inherited motivational tendencies. Ep-stein (1994) proposed a cognitive–experientialmodel of mind that joins key elements ofFreud’s model with evolutionary theory andmodern cognitive science.

In short, and as is well known, Freud’s hy-draulic model of a biological life force seekingto discharge energy is badly outdated. However,when one takes a more conciliatory approach,many of the parallels between Freud’s id andBIT offered here become clear. Freud’s id rep-resents the biological component of the psyche,and BIT is anchored to a modern phylogeneticconception of distal motivation. Freud’s id pro-vides the energy that drives behavior. BIT is aproposal for a nonverbal behavioral system thatguides and coordinates the expenditure of be-havioral energy. Although there are importantdifferences between BIT’s conception of effi-cient energy expenditure and Freud’s hydraulicenergy release model, there are important par-allels as well. Freud proposed that the id oper-ates on the pleasure principle. It can readily beargued that BIT operates on the “pleasure–painparallel fitness principle,” where “fitness” isconceptualized in terms of phylogenetic by on-togenetic selection. This last parallel becomescrucial when one considers the nature ofFreud’s animal ego.

The Parallels

Although many have conceptualized the id asFreud’s “animal mind” (a conception stronglyreinforced by Freud’s famous metaphor of horseand rider representing the id and ego, respec-tively), this is not a fully accurate characteriza-tion. As Freud (1940/1949, p. 18) put it, “theassumption of a distinction between ego and id[in higher animals] cannot be avoided.” Thus,according to Freudian theory, animals haveegos too. This intriguing point raises the ques-tion of how exactly Freud conceptualized therelationship between the ego and the id.

In drive theory, the id provides the impetusfor all behavior. Of course, reality does notallow for immediate gratification, and if an an-imal were to act on every id impulse, it wouldquickly perish. Because of the need for self-

preservation, the animal must be able to inhibitits impulses, and this is the fundamental taskof the ego. Operating on the famous “realityprinciple,” the ego functions by constructingdefenses that block potentially dangerous idimpulses and guides them to more reality-based expressions. The ego is initially part ofthe id. However, as experience impinges uponit, it evolves into an increasingly sophisti-cated problem-solving device that, in properdevelopment, manages a more and more so-phisticated relationship between the demands ofthe internal and external world (Greenspan,1989). The many tricks by which the ego ac-complishes the task of reigning in and redirect-ing the id impulses are labeled defense mecha-nisms. According to Freud, then, behavior re-sults from the dialectical tension between driveand defense.

What is remarkable about characterizingFreudian theory this way is the degree to whichthis conception of the animal mind correspondsto BIT. One can readily draw strong parallelsbetween Freud’s drive and defense conceptionand the various perspectives discussed earlierregarding BIT. The behavioral activation andinhibition systems of the behavioral neuro-sciences, reinforcement and punishment from abehavioral perspective, approach and avoidancefrom a motivational perspective, and benefitsand costs from a neuro-economic perspective allline up rather directly with Freud’s drive–de-fense conception of behavior.

Psychodynamic theorist Drew Westen (1997,1998) has recently built bridges betweenFreud’s ideas and psychological science. Whatis particularly remarkable about Westen’s(1997) conclusions regarding the nature of mo-tivation is that they directly parallel BIT interms of both content and process. In regard tocontent, he explicitly acknowledged that mod-ern evolutionary theory provides the backdropfor understanding the supraordinate goals thatguide human behavioral investments. In regardto process, he also offered a selectionist accountof behavior. Noting that the two broad affec-tive–motivational systems of pleasure–ap-proach and pain–avoid can be readily concep-tualized as behavioral guidance systems,Westen argued that animal behaviors that elicitpositive affects tend to be selected for and be-haviors that elicit negative affects tend to be


selected against.5 The parallels between his sys-tem and Skinner’s did not escape Westen, al-though he seemed more puzzled by the corre-spondence than excited. He wrote:

Emotions and sensory feeling states channel behaviourin adaptive directions in organisms whose behaviour isnot rigidly controlled by relatively automatic instinc-tive processes (see Plutchik, 1980; Sandler, 1981,1987, 1989; Tomkins, 1960, 1980). Affects are mech-anisms for the selective retention of behavioural andmental responses: that is, of the behavioural and men-tal processes a person produces, those that minimizeaversive states or maximize pleasurable feelings willbe more likely to be used again in similar situations.Affect is thus a mechanism for the “natural selection”of responses; regulation of affect becomes a way ofadaptively regulating behaviour . . . . In this view—and paradoxically echoing one of the least psychoan-alytic thinkers in twentieth-century psychology, B.F.Skinner—where the natural selection of organismsleaves off, the natural selection of behaviour throughlearning begins. (Westen, 1997, pp. 529–530)

In short, recent psychodynamic formulationshave argued for a conception of motivation anddynamic unconscious that is very similar to, ifnot identical with, the model offered by BIT.Given that the goal is conciliation and identifi-cation of points of agreement, the finding thatBIT can be readily corresponded with a moderndynamic perspective is quite heartening. Withthe drive–defense dialectic of the id and animalego captured by BIT, we can effectively turnour attention to Freud’s most fundamental ob-servation and begin to understand that whichdifferentiates the human mind from the mindsof other animals.

The Justification Hypothesis and theMind-to-Culture Joint Point

The question of what differentiates humansfrom nonhuman animals has long occupied acentral place in human discourse. According tothe ToK System, human behavior reflects thefourth fundamental dimension in the evolutionof complexity. In addition to the physicochem-ical, biogenetic, and neuropsychological pro-cesses that characterize the behavior of nonhu-man animals, human behaviors are character-ized by sociolinguistic processes.

As depicted in the ToK figure, the ToK Sys-tem proposes that the process of justificationprovides the framework for linking the Mindand Culture levels of complexity, and I refer tothe conceptual link between the two as the jus-

tification hypothesis (JH). The JH consists ofthree fundamental postulates, each of which isexplored here in some detail. The first postulateis that Freud’s fundamental observation wasthat there is a systematic relationship betweenconscious and unconscious processes. In partic-ular, it is argued that Freud observed that con-scious processes serve as a “justification filter”for unconscious motives. The second postulateis that the systematic relationship that Freuddiscovered suggests that the human self-aware-ness system exhibits a complex functional de-sign that likely evolved through the process ofnatural selection. As such, I propose that thehuman ego evolved in response to the selectionpressure created by the adaptive problem ofjustifying one’s actions to others. The third pos-tulate is that the first two postulates provide theframework for understanding the emergence oflarge-scale justification systems. In so doing,the JH provides the scientific foundation for aunified theory of culture. I turn now to the firstpostulate.

Freud’s Fundamental Observation

To my knowledge, Freud never explicitly dif-ferentiated the human ego from the animal ego.Instead, he made the differentiation betweenconscious and unconscious processes.6 The de-marcation between conscious and unconsciousprocesses parallels the demarcation between theanimal and human ego because, for Freud, con-sciousness was intimately associated with sym-bolic language. As Freud (1923/1960, p. 10)stated, if we are to ask “ ‘How does a thingbecome conscious?’ . . . the answer would be:‘Through becoming connected with the word-presentations corresponding to it’.” He went onto state: “Thinking in pictures is, therefore, onlya very incomplete form of becoming con-scious . . . . It stands nearer to unconscious pro-cesses than does thinking in words, and it is

5 Note that this formulation is very similar to Staats’s(1996) three-function learning theory.

6 As those familiar with psychodynamic theory will beaware, Freud differentiated between primary and secondaryprocesses as well, also loosely paralleling the animal–hu-man distinction (Epstein, 1994). Primary process is a moreprimitive mode of immediate responding to the environmentand is differentiated from secondary processes, which arecharacterized by the more logical, realistic mode of reason-ing of which humans are capable.

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unquestionably older than the latter both onto-genetically and phylogenetically” (1923/1960,p. 11). Thus, consciousness in psychoanalytictheory is more closely related to self-awarenessand access to information than it is to the con-cept of sentience (see Pinker, 1997, pp. 134–136), and the conscious aspects of the humanego are essentially equivalent to what is meantby “self” or “I” (McWilliams, 1994).7

With these clarifications about the consciousand unconscious aspects of the human egomade, we are now in a position to examine whatI am claiming to be Freud’s most fundamentalobservation. Freud observed that there are sys-tematic reasons behind the reasons that peoplegive for their behavior. In analytic language,Freud discovered the dynamic unconscious.Many others have similarly argued that this wasFreud’s most fundamental contribution (e.g.,Jones, 1955; Westen, 1999). Freud was, ofcourse, not the first to question the complete-ness of the conscious rationales people offeredfor their behavior. However, he was by far themost influential individual in articulating thesystematic nature of the relationship betweenconscious and unconscious thought. Freudnoted that because humans must contend withthe sociolinguistic context and must determinewhat behaviors are legitimate to express andwhat behaviors are not, humans have a capacitythat allows them to internalize the acceptablerules of conduct, which he called the superego.Freud merged this notion with the conception ofthe id and animal ego discussed earlier. In es-sence, then, Freud ultimately observed that thejustifications that people offer for why they dowhat they do could be understood as arisingfrom the inherent tension between biopsycho-logical drives that guide behavior and the so-ciolinguistic system in which the individual isimmersed.

In conjunction with determining those behav-ioral responses that are justifiable, the humanego is confronted with two tasks. First, it mustinhibit behaviors that are not socially legitimate.The process of inhibiting socially unjustifiableimpulses was the earliest focus of Freud’s at-tention, and he considered repression, the un-conscious process by which such impulses areinhibited, to be the cornerstone of the psycho-analytic paradigm (Eagle, 1998). As AnnaFreud (1966) put it:

The defensive situation with which we have been long-est familiar in analysis and of which our knowledge ismost thorough is that which forms the basis of neurosisin adults. The position here is that some instinctualwish seeks to enter consciousness and with the help ofthe ego to attain gratification. The latter would not beaverse to admitting it, but the superego protests. Theego submits to the higher institution and obedientlyenters into a struggle against the instinctual impulse,with all the consequences which such a struggle en-tails. (pp. 54–55)

A second and related task the human egomust accomplish is that it must develop accept-able justifications for behaviors that are ex-pressed. Simply put, one must generate a legit-imate reason for why one does what one does.The importance and ubiquity of the process ofdeveloping such justifications is seen clearly inNancy McWilliams’s (1994) characterization ofthe ego defense mechanism known as rational-ization:

The defense of rationalization is so familiar that ithardly needs explication here. Not only has this termseeped into common usage with a connotation similarto the one used in psychoanalytic writing, it is also aphenomenon that most of us find naturally entertain-ing—at least in others. “So convenient a thing it is tobe a reasonable Creature,” Benjamin Franklin re-marked, “since it enables one to find or make a Reasonfor everything one has in mind to do.” [italics inoriginal] (quoted in K. Silverman, 1986, p. 39) . . . .

The more intelligent and creative a person is, the morelikely it is that he or she is a good rationalizer. Thedefense operates benignly when it allows someone tomake the best of a difficult situation with minimalresentment, but its drawback as a defensive strategy isthat virtually anything can be—and has been—ratio-nalized. People rarely admit to doing something justbecause it feels good; they prefer to surround theirdecisions with good reasons. Thus the parent who hitsa child rationalizes the aggression by allegedly doing itfor the youngster’s “own good”; the therapist whoinsensitively raises a patient’s fee rationalizes the

7 If the conscious component of the human ego can beconsidered the self, the question arises as to how the un-conscious portion of the human ego might be conceptual-ized. In connection with BIT, the unconscious portion of thehuman ego can awkwardly be characterized as the “humananimal ego.” The general nature of the human animal egocan be seen by taking a cross section of behavioral patternsexhibited by all of the great apes. The common denomina-tors can provide a framework for understanding our “animalnature.” In this light, the human animal ego can be thoughtof as the behavioral investment part of the mind that worksthrough visuospatial information processing and motiva-tional–affective behavioral guidance systems. It closely cor-responds to what Epstein (1994) called the experientialsystem.


greed by deciding that paying more will benefit theperson’s self-esteem; the serial dieter rationalizes van-ity with an appeal to health. (pp. 124–125)

In summary, the processes of inhibiting unjus-tifiable impulses and generating acceptable ra-tionales for those impulses that are expressedare some of the most basic elements of theFreudian paradigm.8

With the two central elements of the humanego conceptualized in terms of inhibition andjustification, I can now state clearly the firstpostulate of the JH: Freud’s fundamental obser-vation was that the human ego or self-awarenesssystem functions as a justification filter for un-derlying motives. We saw that Skinner’s ideasbecame more readily integrated with other ap-proaches when viewed from a modern phyloge-netic functional perspective. The second postu-late of the JH is that the systematic relationshipbetween conscious and unconscious processesbecomes much more readily understandablewhen one views the structural organization ofthe human self-awareness system as an evolvedsolution to the adaptive problem of justification.

The Evolution of the Human Ego and theAdaptive Problem of Justification

When confronted with complex functionaldesigns in nature, it is useful to employ a re-verse engineering perspective (Dennett, 1995;Pinker, 1997). A reverse engineering approachcapitalizes on Darwin’s fundamental insightthat the complex functional design seen in or-ganisms is a product of natural selection. Like adetective who matches a crime to a particularcriminal, a reverse engineer matches organismdesign features to problems in the ancestralenvironment. This theoretical lock-and-keymatching process is crucial because it serves asa guide to generating hypotheses about theevolved function of the characteristic in ques-tion (Mayr, 1983). As with a detective whomust first determine that a crime has been com-mitted, a reverse engineer must demonstratethat the characteristic in question exhibits acomplex functional design. This is a crucial stepin the process. Just as not all persons killed bygunshot are murder victims, not all biologicalcharacteristics are adaptations, a point elo-quently elaborated on by sociobiological criticsGould and Lewontin (1979). As such, like adetective who can be too reckless and make

unwarranted accusations or too cautious and failto make reasonable ones, a reverse engineeringtheorist must navigate the dialectical tensionbetween the Scylla of false positives and theCharybdis of false negatives.

If the presence of functional design is reason-ably inferred, one then posits an adaptive prob-lem that might account for the selection pres-sure that resulted in the present design. As witha detective who must establish motive, means,and opportunity for a suspect, a reverse engi-neer must effectively argue that the selectionpressure was significant and that the designfeature could have evolved given the phylo-genic history. The explanation should be funda-mentally consistent with available evidence,serve as a useful heuristic, offer a parsimoniousaccount of the evidence available, and ulti-mately make falsifiable predictions.

Framed this way, the possibility arises thatthe human ego or self-awareness systemevolved in response to some new selection pres-sure faced by our hominid ancestors. The sec-ond postulate of the JH is that the human ego orself-awareness system evolved because, for thefirst time in evolutionary history, our hominidancestors had to justify their actions to others.In making the case, it is argued that the natureof human self-awareness is fundamentally dif-ferent than that of other animals and that self-awareness is dependent on specific types ofinformation-processing systems in the brain. Itis also argued that the evolution of languagemust have created a fundamentally new adap-tive problem for our human ancestors: the prob-lem of justification. It is further proposed that

8 There are, to be sure, many ego defense mechanismsother than repression and rationalization (e.g., Conte &Plutchik, 1995). However, I believe that viewing the humanego as a justification filter that must either inhibit or justifyactions provides a framework for understanding many of thedefense mechanisms. Denial, suppression, isolation, com-partmentalization, and withdrawal, in addition to repression,represent a class of defenses that are characterized by theinhibition component. Rationalization, intellectualization,and moralization can all be readily understood as the de-velopment of justifications. Other human ego defenses, suchas reaction formation and turning against the self (McWil-liams, 1994), can be understood as combinations of inhibi-tions and justifications. For example, consider a reactionformation in a homophobic who clearly has homosexualfantasies. The function of the anti-homosexual belief systemis to facilitate the repression of what the homophobic’ssuperego perceives to be a deviant sexual urge.

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the ability to effectively justify one’s actionsmust have been directly related to the amount ofsocial influence one achieved and, thus, wasclosely tied to reproductive success (see Robins,Norem, & Cheek, 1999, and Sedikides & Skow-ronski, 1997, for a discussion of related issues).

As with evidence such as fingerprints left atthe scene by a perpetrator, this matching pro-cess leads to several implications. For example,this formulation clearly predicts that the humanego should be designed in such a way that itallows humans to effectively justify their ac-tions to others in a manner that tends to maxi-mize social influence. Some of the character-istics of the human ego, as elucidated byneuropsychology, social psychology, cognitivepsychology, and developmental psychology, arereviewed to demonstrate that there is a largebody of general human psychological researchthat is consistent with this proposition. It isconcluded that the problem of justification is aprime suspect for a selection pressure that re-sulted in the evolution of the human ego. Stateddifferently, the argument will have been madethat the human ego can be thought of as themental organ of justification.

Evidence for a Human Self-AwarenessSystem

A key element of the current proposal is thathuman self-awareness is fundamentally differ-ent than that of other animals. This is not anovel proposal. Many theorists and philoso-phers have suggested that it is the presence ofthe ego or self-awareness system that differen-tiates human consciousness from the conscious-ness of other animals. I have already discussedFreud’s views. Dennett (1996) made the distinc-tion between first-order and second-order inten-tional beings. A first-order intentional being hasa mental life, consisting of beliefs and desiresabout many things, but not beliefs and desiresabout beliefs and desires. In short, first-orderintentional creatures are aware, but not awarethat they are aware. Second-order intentionalbeings, namely humans, have beliefs and de-sires about beliefs and desires; they are aware oftheir awareness. Likewise, Edelman (1989,1992) distinguished between primary con-sciousness and higher order consciousness. Hedefined primary consciousness as the state ofbeing mentally aware of things in the world, of

having mental images of the present. Higherorder consciousness is awareness of the self orthe process of being conscious of being con-scious. He argued that it is intimately tied tolanguage and is only possessed by humans.Many others have made similar proposals9 (e.g.,Damasio, 1998; Dobzhansky, 1964; Duval &Wicklund, 1972; Epstein, 1994; Gould, 1993;James, 1890/1950; Kant, 1781/1996; Ornstein,1972).

In addition to theoretical and philosophicalarguments, there have been some empirical in-vestigations of animal self-awareness. Such in-vestigations are obviously difficult, but the in-genious technique of the mirror self-recognition(MSR) task developed by Gallup (1970) hasyielded interesting results. Success at the MSRsuggests at least a rudimentary cognitive capac-ity to become the focus of one’s own attention.Success does not mean that the animal canintrospect or be self-reflective (Mitchell, 1994).On the other hand, failure to succeed at theMSR task is a result that is much easier tointerpret and is good evidence for the lack ofany genuine capacity for self-awareness. Whatis remarkable, then, is that virtually all animalsfail the MSR task. Only adult chimpanzees,bonobos, orangutans, and bottlenose dolphinsseem to regularly pass the task. Even most adultgorillas fail to pass the test (Parker, Mitchell, &Boccia, 1994). Thus, the vast majority of organ-isms do not possess even the most basic cogni-tive capacities required for self-awareness. Hu-mans generally pass the MSR task at approxi-mately the age of 18 months. When oneconsiders how adult humans explain their ac-tions to others, worry about their death, developmyths to account for their existence, and plantheir actions weeks, months, and even years inadvance, the gulf in self-awareness between hu-mans and even our nearest animal relatives istruly astounding.

Other empirical evidence comes from studiesof individuals with brain injury. Neuropsy-

9 As is often the case when discussing the nature ofconsciousness, there is potential for confusion here. Den-nett’s first-order intentionality and Edelman’s primary con-sciousness loosely correspond to Freud’s dynamic uncon-scious (primary processes), whereas the conscious portionof the human ego (secondary processes) in Freud’s systemcorresponds to Dennett’s second-order intentionality andEdelman’s higher order consciousness.


chologists have demonstrated that there are lin-guistically based declarative memory systemsin the brain that store information in a mannerthat allows the individual to consciously re-member what happened (e.g., Schacter, 1993).In addition, brain damage can result in grossdisturbances in self-awareness, a conditionknown as anosognosia (Schacter, 1990). Suchindividuals will often exhibit a remarkable, al-most unbelievable, lack of self-awareness, oftendespite intact intellectual functioning as mea-sured by intelligence tests. Examples includeindividuals who completely deny that half oftheir body is paralyzed or who report that theycan walk despite being confined to a wheelchair(Barr, 1998). Many neuropsychologists explainthese phenomena as disturbances in the self-awareness system (Amador & David, 1998). Asdiscussed in more detail later, the languagestructures of the left hemisphere are intimatelyrelated to the human capacity for self-aware-ness. Anosognosia is the consequence of righthemisphere damage, and it has long been pro-posed that the damage results in the isolationof language structures in the left hemispherethat allow for self-reflection and self-reporting(Geschwind, 1965).

The enormous difference between human andanimal self-awareness and the presence ofneuro-information-processing systems that al-low for self-awareness, in addition to the reviewof Freudian theory offered earlier, strongly sug-gests that the capacity to be aware of our per-ceptions, thoughts, and feelings is part of thecomplex functional design of the human brain.A reasonable inference from these observationsis that the self-awareness system is a mentalorgan shaped by natural selection. However, thecase is currently far from conclusive. It is stillpossible that the human ego is simply a byprod-uct of other evolved capacities. If a particularadaptive problem could be identified that hasbeen present only in the hominid line and wouldrequire an elaborate self-awareness system, thenthe case that the human ego was the productof natural selection would be significantlystrengthened.

Language and the Emergence of theProblem of Justification

Although there have been a few notable dis-senters (e.g., Chomsky, 1972; Gould, 1987),

most evolutionists and psycholinguists agreethat human capacity for language evolvedthrough the process of natural selection (e.g.,Deacon, 1997; Pinker, 1994). These theoristsnote facts such as the following: Humans ev-erywhere possess language; there is a develop-mental period in which children acquire lan-guage easily and rapidly; children learn to speakwith remarkably little direct instruction; thereare well-documented language processing cen-ters in the brain; and the vocal chords of humansare elaborately constructed to allow for ex-tremely complex sounds to be generated(Lieberman, 1998). Further, other animals (e.g.,chimpanzees) can obtain only a crude approxi-mation of human language despite immensetraining (Pinker & Bloom, 1992). Finally,groups of children raised in the absence of anative language have been known to develop afully functioning language in as little as a singlegeneration (Bickerton, 1995).

In addition to these elements, the capacity forlanguage results in many advantages. It allowsvaluable information to be shared cheaply andeffectively, which in turn allows for more syn-ergistic and cooperative relationships (Pinker,1997). Language also allows for the accumula-tion of information across the generations. Fur-thermore, the ability to symbolically representperceptual objects and their transformations inthe forms of nouns and verbs results in thecapacity to elaborate, refine, connect, and re-member a great number of new concepts (Dea-con, 1997). Finally, the absence of useful alter-native explanations makes the notion that thehuman capacity for language is a product ofnatural selection quite solid (Pinker, 1994).

Importantly for present considerations, lan-guage also provides a means to more directlyaccess and assess the thoughts and intentions ofothers. Although chimpanzees can clearly sendthe message that they are angry or scared, with-out a symbolic language it is almost impossiblefor them to communicate the reasons why theyfeel that way. Humans are different. Unlikechimps, language allows humans to ask and beasked about the thought processes associatedwith their behaviors. Questions such as “Whydid you do that?” “What gives you the right tobehave that way?” and “Why should I trustyou?” force the issue. Obtaining informationabout what others think, what they have done,what they plan to do is obviously important for

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navigating the social environment in moderntimes, and given that humans have always beenan intensely social species, there is every reasonto believe that it was equally essential in theancestral past. As such, it is highly likely that ashumans developed the cognitive–linguistic ca-pacity to access another’s thoughts, they did sowith vigor (Barkow, 1992).

As a consequence of language, then, humansbecame the first organism that had to explain itsthoughts and actions to others. To offer an ex-planation for one’s behavior, one must havesome degree of access to one’s thoughts (Den-nett, 1996). That is, to answer the question“Why did you do that?” one must be able toself-reflect and then translate those thoughtsinto a symbolic form that can be interpreted.This is the problem of justification.

Although we frequently offer reasons for whywe do what we do, a moment’s reflection re-veals an important insight. The ability to gen-erate such answers reflects an extraordinarycomputational capacity. Given that modern sci-ence cannot provide a coherent explanatoryframework for human behavior in general, howis it possible that one could offer explanationsfor the behavior of a human in particular? If onecannot explain the general, explanations of theparticular are hopeless. Indeed, from the stand-point of pure logic, until we have at least agenerally agreed upon framework for under-standing human behavior, we should technicallyanswer “I do not know” to the question “Whydid you do that?” (see Hofstadter & Dennett,1981, for a philosophical discussion of similarissues). Of course, there are no human societiesin which people, in the spirit of pure logic,never provide explanations for why they dowhat they do. Instead, humans everywhere con-struct elaborate linguistic systems of thoughtthat attempt to provide a causal explanatoryframework for their behavior and the behaviorof the people around them.

Over the past two decades, there has been adramatic increase in interest in how individualsform “folk” theories of their own mind and theminds of other people. Consistent with the viewtaken here, much of this research was sparkedby considering the adaptive advantages associ-ated with a skilled understanding of the socialenvironment (Humphrey, 1976; Jolly, 1966).Furthermore, and consistent with the JH regard-ing the uniqueness of human capacities for un-

derstanding self and other, empirical researchsuggests that the “folk” psychological capaci-ties of the other great apes pale in comparisonwith those of humans (Ponvinelli & Prince,1998). The JH suggests that humans have sucha strongly developed sense of folk psychologybecause they are the only species that has had toarticulate what they think to others. Likewise,humans are the only animals that have had toevaluate the legitimacy of others’ explanations.

However, accessing one’s thoughts and feel-ings and generating an explanation of one’sactions is only part of the problem generated bya sociolinguistic environment. Even if one wereable to give a complete and accurate explana-tion for one’s actions, it would not always bethe best thing. The difficulty becomes readilyapparent when one considers how different ex-planations given for behaviors result in differentsocial reactions. If you strike a comrade with astick, it matters whether you tell him it wasdone by accident or on purpose. If your matefinds you alone with an attractive member of theopposite sex, it matters how you explain theevent. If you are bargaining with a stranger, youcan get more resources if you emphasize thatthe resources you are trading are valuable, andso on. Different explanations result in differentreactions because they communicate differentthings about the self to the listener. And, aseveryone is likely to be aware, informationabout the self varies in the degree to which it isbeneficial to be shared. Information that one islazy, lying, ineffective, self-centered, or weak isoften accurate but is obviously costly in termsof social influence. Communicating that one isin control, intelligent, moral, competent, fair,and honest is usually beneficial in terms ofsocial influence.

An implication of this analysis, which hasbeen offered by several evolutionary theorists(e.g., Alexander, 1979; Goleman, 1985; Trivers,1985), is that people should be adept at someforms of self-deception. Furthermore, and con-sistent with the present formulation, there is astrong connection between psychodynamic the-ory and self-deception, and several theoristshave noted the interrelationships between evo-lutionary analyses of self-deception and the psy-chodynamic models of conscious and uncon-scious processes (e.g., Nesse & Lloyd, 1992).Psychodynamic theorists Slavin and Greif(1995) put the issue as follows:


Deception is a pervasive, universal intrinsic feature ofall animal communication. In pursuit of their owninclusive fitness, organisms do not simply communi-cate to convey a truth about reality to others, but ratherto convey a “presentation of self”: to hide certainfeatures and selectively accentuate others that theyneed or desire others to perceive. The unique feature ofhuman symbolic communication—its displacementfrom direct observation—greatly amplifies this powerboth to convey realities accurately and to hide them.[italics added] (p. 149)

To summarize, effectively justifying one’sactions almost certainly was a new, difficult,and extremely important problem for our ances-tors to be able to solve, precisely the type ofadaptive problem that would lead to strong se-lection pressures and rapid evolutionary change.Solving the problem of justification requiresmany new cognitive capacities such as self-representation, generating causal explanationsfor why one behaved in a certain way, andevaluating the legitimacy of others’ actions.Furthermore, the problem of justification sug-gests that the evolutionary solution should in-volve a system of knowing that has more readyaccess to certain aspects of the self than otheraspects of the self (i.e., access to information asto why the self behaved in a justifiable manner).Finally, several theorists have made connec-tions between evolutionary analyses of self-de-ception and modern psychodynamic models ofthe human mind.

The Human Ego as the Mental Organ ofJustification

The case has now been made that it is plau-sible that the human ego evolved to solve theproblem of justification. The human self-aware-ness system exhibits a design indicative of nat-ural selection and appears to be unique to theanimal kingdom. It has also been shown that theproblem of justifying one’s actions to others isa problem unique to hominids and is ubiquitousin human affairs. As such, it is a plausiblecandidate for the selection pressure that gaverise to the human ego. As currently it stands, theJH is at the status of a good just-so story (Gould& Lewontin, 1979). To return to the detectivemetaphor, there appears to be good circumstan-tial evidence for the JH. We now need to ex-amine the current scene and look for hard evi-dence. We can do this because the JH carrieswith it implications for how the human ego

should be designed. If the human ego evolvedbecause of the adaptive problem of justifyingone’s thoughts and actions to others, then thehuman self-awareness system should exhibitdesign features indicative of this. To be clearabout the implications of the JH, it is useful tobriefly compare and contrast the concept ofjustifications with pure explanations.

Justifications are the linguistic reasons weuse to validate our actions or claims to others. Ifit is claimed that certain explanations validatecertain actions, justifications inevitably involveclaims about what ought to be. For example,justifications such as “I should be leader be-cause I killed the most antelope,” or “I hit himwith a stick because he called me a liar,” or “Iam rewarding you because you received a goodgrade” involve claims about what ought to be.Because of this, justifications consist of bothexplanations and value-based claims. Accurateand inaccurate are not redundant with good andbad. For example, consider an abused wife whobuys a gun and kills her husband. Everyonemight agree on the facts of the case. However,some people will find her justification, “He con-trolled and beat me regularly,” as legitimate andwill believe that the woman should not be pun-ished at all. Others will believe that this is not agood justification and think that she should bepunished, perhaps even put to death. Con-versely, in the case of pure explanations, accu-rate is defined as good and inaccurate as bad.Thus, justifications entail two separate dimen-sions (accuracy and value), whereas pure expla-nations are a special case of justifications inwhich the two dimensions are reduced to asingle dimension (accuracy � value).

Comparisons between the ideological goalsof the institutions of law and science help tomake the differences between justifications andexplanations clearer. The goal of law is to cod-ify which behaviors are not justifiable, and thelaw functions as a system of interlocking justi-fications that formally define the rules of thesociety. On the other hand, the goal of science,at least in theory, is to factor out human valuesand to develop representations of reality that areas accurate as possible (Wilson, 1998). Ofcourse, as many social constructivists havepointed out, explanations and justifications arenot so neatly separated in the practice of sci-ence, or anywhere else for that matter. None-

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theless, the ideological goals of the two institu-tions help illustrate the conceptual distinction.

Because the law is a good example of ajustification system, an analogy comparing thehuman ego with the role of defense attorney ishelpful in clarifying the implications of the JH.If the adaptive problem created by languagewere simply the problem of self-explanation,we would expect the human ego to functionsimilar to a court reporter. A court reportersimply translates the transactions of the trialinto a symbolic record as accurately as possible.Likewise, if the primary function of the humanego is simply self-explanation, then individualsshould work to convey information about theself as accurately as possible. Of course, the roleof defense attorneys is quite different. They toomust be concerned with the accuracy of theirstatements. However, they are also very goaloriented. They must explain their clients’ ac-tions in a manner that others will both believeand respond to favorably. Because the role of adefense attorney closely parallels the functionof the human ego proposed by the JH, we canuse the analogy to more clearly develop thepredictions the JH makes for how knowledgeabout the self should be organized.

The interpreter function. Saying that youhave no idea why your client did what he did israrely a good defense. It is generally better tooffer benign explanations so long as they makesense, and the JH proposes that the human self-awareness system functions to generate accept-able interpretations for one’s behavior. An im-plication of this proposition is that people willgenerate reasons for their behavior even if theself-awareness system does not have access tonecessary information. A unique circumstancein the field of neuropsychology actually allowedthis implication to be explicitly examined.

Michael Gazzaniga (1992) found, throughstudying split-brain10 patients, that the left hemi-sphere generates explanations about the behav-ior of the individual even when it does not haveaccess to the necessary information. Gazzanigafound that if simple commands were flashed tothe right hemisphere, such as “walk around” or“laugh,” the patients would follow these com-mands (the right hemisphere does have rudi-mentary linguistic capacities). However, whenasked to justify why they were performing thesebehaviors (walking or laughing), patients wouldconfabulate a reason such as “I am going to get

a drink” or “Because you guys are so funny.” Inother words, their ego justified their behavior inthe absence of necessary information. That thehuman ego appears to be designed in such a waythat it develops socially acceptable interpreta-tions of the individual’s behavior in the absenceof complete information is a fundamental pieceof evidence consistent with the JH. Gazzaniga(1992) characterized the system of cognitiveprocesses that allows for these interpretations tooccur as “the interpreter.” He wrote:

It is easy to imagine selection pressures promoting aninterpreter mechanism in the human brain. A systemthat allows for thought about the implications of ac-tions, generated by both others as well as the self, willgrasp the social context and its meaning for personalsurvival . . . . Also, the interpreter function generatesthe possibility for human uniqueness . . . . I think thatthe built-in capacity of the interpreter gives each of usour local and personal color. (Gazzaniga, 1992, p. 134)

The self-serving bias. Defense attorneysare, by definition, biased in terms of how theyexplain their client’s behavior, and they work toexplain their client’s behavior in a way thataffords the most social influence. Thus, accord-ing to the JH, people should tend to explaintheir behavior and the things that happen tothem in a manner that affords the most socialinfluence. In an article titled “The TotalitarianEgo,” Greenwald (1980) surveyed the vast so-cial psychological literature on how informationabout the self is processed. He likened the hu-man ego to a personal historian that is totalitar-ian and relentless in the manner in which itrevises and fabricates history to make the indi-vidual seem more important, cognitively con-sistent, altruistic, and effective than the evi-dence would warrant. Taylor and her colleagues(Taylor & Brown, 1988, 1994; see also D. L.Krebs & Denton, 1997) concluded that mostpeople (a) view themselves in unrealisticallypositive terms, (b) believe they have greatercontrol over their environment than is actuallythe case, and (c) have a more rosy view of theirfuture than the base rate data could justify.Interestingly, these researchers also demon-

10 In split-brain patients, the left hemisphere can nolonger communicate with the right hemisphere because thecorpus callosum has been severed. Information flashed tothe left visual field is only processed by the right hemi-sphere, and vice versa.


strated that such self-enhancing tendencies arepositively related to mental health.

The tendency for people to evaluate them-selves in an overly positive manner and to ex-plain bad outcomes in terms of external causesand good outcomes in terms of internal causeshas been confirmed in literally hundreds of psy-chological studies and can be considered one ofthe most robust findings in social psychology.Demonstrating the pervasiveness of this ten-dency, Friedrich (1996) found that after stu-dents were taught about the self-serving bias,they tended to see themselves as less self-serv-ing than most, a phenomenon he humorouslycoined the “ultimate self-serving bias.” Asmade clear by the defense attorney metaphor,because people will want relationships withmore skillful, giving, powerful people, the morepositive picture of oneself one can justifiablypaint, the better.

Cognitive dissonance. According to the JH,and as is made clear by the defense attorneymetaphor, individuals should experience anxi-ety if they hold two unjustifiable propositionssimultaneously. The reason is that holding twoinconsistent beliefs would mean that the advo-cated belief systems would be vulnerable tobeing shown to be inaccurate. This, in turn,would mean criticism from others.

Imagine the following: After completing anextremely boring task for a psychology experi-ment, the experimenter asks you to do her afavor. Her graduate assistant, who was sup-posed to inform the participant that the task isexciting and enjoyable, is not there and sheneeds someone to fill in. She then offers youeither $1 or $20 to help her out. After youcomply, she then asks you what you really feltabout the task. As is now well known, if youreceived $1 you rate the task as more enjoyableand less boring than if you received $20.

Why would people alter their beliefs in thismanner? If one extends the scenario, an obviousexplanation presents itself. Imagine it is some-time later and you come across the participantyou lied to. “Hey,” he calls, “that task wasboring as anything. Why did you lie to me andtell me it was exciting?” If the experimentergave you $20, you have a reasonable justifica-tion and might respond “Sorry, but it was some-thing they were going to tell you anyway andshe gave me $20.” If, however, you only re-ceived $1, it is much harder to justify that you

lied. Yet, if you did not find the task to be sobad, you could defend yourself as follows: “Theexperimenter asked me to say that. And I didn’tthink the task was so bad.” Literally hundreds ofexperiments have supported the finding thatpeople doctor their belief systems so that theirbehavior is presented in as justifiable a manneras possible (Aronson, 1996).

It is particularly important to note that theprocess operates outside of self-awareness. Thatis, when asked about her or his thought pro-cesses, no one responds “I initially felt that thetask was boring, but then when I found myselfwilling to lie about it for only a dollar, I realizedthat this made me vulnerable to attack and crit-icism for committing a fairly unjustifiable act.As such, I changed my belief in how boring thetask was so that I would be in a better place tojustify my actions.” People are conscious of theresult of the dissonance reduction process butare not conscious of the process itself. Likewise,children are not explicitly taught about disso-nance or about how to adjust their beliefs ac-cordingly. The findings associated with cogni-tive dissonance research are obviously directlyconsistent with the JH, and the implicit natureof cognitive dissonance lends further credenceto the JH.

The capacity to reason. One only needs toread the lucid descriptions of great ape behavioroffered by primatologists such as Franz de Waal(1982), Jane Goodall (1986), and Diane Fossey(1983) to realize that our nearest relatives liveintricate and complicated social lives. At thesame time, one only needs to confront our greatape relatives with tasks that require basic ana-lytic reasoning to realize that the gulf betweenhumans and other great apes in this domain isoceanic (Byrne, 1995). Why, according to theJH, would humans be good reasoners? For thesame reason that we pay smart lawyers morethan stupid ones. Determining logical inconsis-tencies in one’s own and others’ justificationsystems is obviously of crucial importance. Theonly way to identify such logical inconsisten-cies is through the process of analytic reason-ing. Some evolutionary psychologists are fondof pointing out that there cannot be a domain-general learning device because of the frameproblem and because there are no general adap-tive problems that must be solved (Tooby &Cosmides, 1992). The JH challenges this asser-tion, at least in the sense that to solve the

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problem of what is and what is not justifiablerequires the capacity for general, analyticreasoning.

The JH further suggests that the general rea-soning capacity in humans emerged out of de-termining what is and what is not justifiable inthe social context. This gives rise to anotherimplication of the JH. If social reasoning gaverise to general reasoning, then humans shouldbe particularly adept at social reasoning, at leastin comparison with other forms of general rea-soning. This is precisely the case. Cognitivepsychologists have long noted that people rea-son more effectively about what they may,ought, or must not do in a given set of socialcircumstances than they do when reasoninggenerally. Cognitive psychologists refer to rea-soning about socially justifiable acts as deonticreasoning. After noting how crucial deontic rea-soning is across social situations, Cummins(1996a) summarized the findings in adults asfollows:

In contrast to their performance on statistical reasoning(e.g., Kahneman, Slovic, & Tversky, 1982), indicativereasoning (e.g., Wason & Johnson-Laird, 1972), andmathematical or scientific problem-solving tasks (e.g.,Chi, Feltovich, & Glaser, 1981), adults typically per-form consistently and well on tasks requiring deonticreasoning (e.g., Cheng & Holyoak, 1985, 1989; Griggs& Cox, 1983; Manktelow & Over, 1991, 1995). In fact,so robust and reliable is performance on deontic tasksthat numerous proposals have been put forth to explainit. (p. 823)

Cummins (1996a) proceeded to demonstratethat 3- and 4-year-old children also show supe-riority in deontic reasoning. In a separate articlearguing that the ability for deontic reasoning isa consequence of evolutionary pressures, Cum-mins (1996b) observed that deontic reasoning“emerges early in childhood, is observed re-gardless of the cultural background of the rea-soner, and can be selectively disrupted at theneurological level” (p. 160). In short, and indirect accordance with the JH, there is an abun-dance of evidence that suggests that humansreason better about what is and what is notsocially justifiable than they do when reasoningabout abstract general truths.

I have reviewed data relevant to some of themore direct implications about self-knowledgethat fall out of the JH. In accordance with theJH, there are recently evolved brain structuresthat allow humans to interpret their own behav-ior and to generate acceptable reasons for their

behavior. Massive amounts of data indicate thathumans tend to hold the most positive picture ofthemselves that can be reasonably justified.Massive amounts of data indicate that humansdoctor their beliefs to maintain a socially justi-fiable image of themselves. And humans are farbetter general reasoners than the other greatapes and far better social reasoners than analyticreasoners. These findings, when combined withFreud’s fundamental observation regarding thenature of the human ego as a justification filterand the logical necessity that evolution of lan-guage generated the adaptive problem of justi-fication, strongly suggest that we can considerthe human ego the mental organ of justification.

The Foundation for a Unified Theory ofCulture

The third postulate of the JH is that it pro-vides a framework for building a conceptualbridge across the great rift that currently dividesscientific thought. On the one hand, there are thenatural and biological sciences. On the otherhand, there are the social sciences, including thehuman psychologies (e.g., social and cultural),sociology, anthropology, economics, and polit-ical science, to name a few of the more prom-inent disciplines. The former disciplines are of-ten characterized as the hard sciences and aregenerally seen as more empirical. The latterdisciplines are associated with more construc-tivist epistemologies, and the science is morehistorically and contextually based.

In Consilience, Wilson (1998) characterizedthe rift between the natural and social sciencesas one of the great remaining problems in sci-ence. He further suggested that the lack of aconsilient framework that integrates the naturaland social sciences prevents the science of hu-man behavior from effectively progressing. Heobserved:

We know that virtually all of human behavior is trans-mitted by culture. We also know that biology has animportant effect on the origin of culture and its trans-mission. The question remaining is how biology andculture interact, and in particular how they interactacross all societies to create the commonalities ofhuman nature. What, in the final analysis, joins thedeep, mostly genetic history of the species as a wholeto the more recent cultural histories of far-flung soci-eties? That, in my opinion, is the nub of the relation-ship between the two cultures. It can be stated as aproblem to be solved, the central problem of the social


sciences and the humanities, and simultaneously one ofthe great remaining problems of the natural sciences.

At present time no one has a solution. But in the sensethat no one in 1842 knew the true cause of evolutionand in 1952 no one knew the nature of the geneticcode, the way to solve the problem may lie within ourgrasp. (p. 126)

According to the representation provided bythe ToK System, Wilson is arguing that thetheoretical joint point that connects the scienceof culture to the rest of the sciences is currentlymissing. Importantly and also directly consis-tent with the ToK System, in his keynote ad-dress presented at the 2000 convention of theAmerican Psychological Association, Wilsonrightly proclaimed that the field of psychologyexisted between the natural and social sciencesand thus would be instrumental in building thebridge between them. An implication of Wil-son’s claim is that a unified psychology wouldsuccessfully join the two cultures and, in sodoing, a consilient picture of all of the scienceswould emerge.

Taken together, BIT, the JH, and the ToKSystem suggest the veracity of Wilson’s consil-ient hypothesis. The essence of culture is thepresence of large-scale belief systems that func-tion to coordinate and legitimize human behav-ior. The fundamental point of a social scienceperspective is that human behavior must beunderstood in the context of the larger sociolin-guistic system in which it is immersed (e.g.,Gergen, 1985). The theoretical problem hasbeen that there was no systematic way to un-derstand how the evolution of the mind in gen-eral, and the human mind in particular, led tothe emergence of these cultural justification sys-tems. As such, social scientists have tended tofocus simply on the systems themselves and notconcern themselves with the origins of theiremergence (e.g., Geertz, 1973). As an inevitableconsequence of this starting point, the socialscience models that arose essentially lacked anysystematic framework for integrating biopsy-chological causation and thus were obviouslyincomplete (Tooby & Cosmides, 1992). Unfor-tunately, the biopsychological models built bytaking a bottom-up perspective have proven in-adequate for providing a framework for under-standing the emergence of the large-scale justi-fication systems examined by cultural scientists.The absence of a large-scale meta-theoreticalframework that could effectively incorporate

physical, biological, psychological, and socialcausation in explaining human behavior has re-sulted in the rift between the two cultures. TheToK System, with its depiction of the corre-spondence between the four layers of complex-ity and the four domains of science, providesthe meta-theoretical framework necessary forconsilience between the natural and social sci-ences to be achieved.

Some Considerations in Applying theUnified Theory

The current focus on theory has stemmedfrom the argument that psychology’s biggestproblems are epistemological in nature. Ofcourse, the ultimate value of the proposal willbe in the degree to which it increases our un-derstanding of psychological phenomena. Im-plicit in the current proposal is the notion that ifpsychologists adopt the unified theoretical ap-proach, then a much more comprehensive viewof specific psychological phenomena willemerge. The argument is similar to the onemade by Sternberg and Grigorenko (2001), whostated that a multiparadigmatic perspectivewould result in a deeper understanding of psy-chological phenomena. A major omission intheir approach, however, was the fact thatadopting a multiparadigmatic approach is noteasy because crucial epistemological differ-ences render the various paradigms, as they arecurrently defined, incompatible. The approachoffered here can be considered a metaparadig-matic approach, which agrees with Sternbergand Grigorenko’s (2001) call for convergingoperations in the study of psychological phe-nomena but further suggests that what is neededis epistemological consistency and a sharedconceptual framework.

The current analysis also suggests that theintroduction of the two large concepts of behav-ioral investments and justifications will effec-tively organize much extant psychological re-search and provide a framework for understand-ing everyday psychological phenomena. Acursory glance reveals the concepts of behav-ioral investments and justifications to be almostomnipresent in human affairs. To provide justone of endless possible examples of how theseconcepts already implicitly influence everydaythinking, consider Sternberg and Grigorenko’s(2001) analysis of how researchers may become

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unfortunately channeled into one particular av-enue of investigation:

Researchers may seek to maximize the return on theirtime investment and use what they have learned asmuch as possible. Even if they come to see the flaws oftheir preferred methodology, they may come to viewthe time invested as a sunken cost and seek to justify oreven redeem the investment anyway. (p. 1072)

The two broad concepts also readily lend them-selves to phenomena currently under scientificinvestigation. A broad number of psychologicalphenomena have already been surveyed, such asreinforcement and extinction, the self-aware-ness system, cognitive dissonance and attribu-tional research, verbal versus nonverbal infor-mation processing and hemispheric specializa-tion, and deontic reasoning, among others.Although these psychological concepts wereused to bolster the theoretical arguments, theconverse can readily be done; that is, the theo-ries offered here can be used in empirical in-vestigations of these phenomena.

There are many other areas to which theanalysis can be extended. Consider, for exam-ple, the construct of depression. The mentalhealth community still struggles monumentallywith defining this concept (e.g., Maj & Sarto-rius, 1999). Is depression a normal human re-action? Is it a cognitive disorder? A behavioraldisorder? Is it a biological disease? Of course, itdepends in part on one’s definitional system,which is why a broad, shared definitional sys-tem is so essential. BIT readily provides a clearfunctional understanding of depression. Ani-mals should decrease their behavioral expendi-ture of energy if their behavioral investmentsconsistently result in no functional effect on theanimal–environment relationship. In this light,depression is a state of behavioral shutdown(Henriques, 2000), and research on animalsstrongly conforms to this conception (e.g., Se-ligman, 1975).

The metaparadigmatic perspective allowsone to easily move among behavioral, cogni-tive, psychodynamic, and biopsychiatric per-spectives when conceptualizing depression.From a behavioral perspective, consider whathappens if the behavioral shutdown results inincreasingly greater loss. If the shutdown cre-ates greater loss, then a vicious cycle ensues inwhich the behavioral reaction results in the ad-ditional loss, resulting in greater shutdown andso on. The individual can also justify behavioral

investments and events in a problematic fash-ion, and overly negative or pessimistic interpre-tations can result in vicious depressive cycles aswell, which is essentially the cognitive formu-lation (e.g., Beck, 1976). Or, from a more psy-chodynamic perspective, consider how the self-criticisms so prominent in depressed individualsmight sometimes function to justify submissionand the inhibition of aggressive impulses. Theunified approach allows one to consider depres-sion from each of these perspectives under thesame general framework of understanding.

The unified perspective also allows for a bio-psychiatric conceptualization and clarifies thedistinction between a disease and a behavioraldisorder. As I have argued elsewhere (Hen-riques, 2002), the concept of “disease” can bethought of as an applied biological constructthat can be defined as a harmful breakdown inthe function of an evolved mechanism (seeWakefield, 1999). This construct can be con-ceptually differentiated from psychological dis-orders in which rigid, maladaptive behavioralpatterns result from vicious behavioral cycles,as just described in the context of depression.Thus, severe depressive responses that occur inthe absence of behavioral ineffectiveness or loss(e.g., Solomon, 1998) can be considered depres-sive diseases, because such occurrences reflect abreakdown in the functioning of the basic bio-psychological architecture. Ultimately, the con-ceptual distinction between psychological dis-orders and diseases may have significant impli-cations for the frequently strained relationshipbetween clinical psychology and psychiatry.

Conclusion

A well-defined subject matter, a shared lan-guage, and conceptual agreements about thefundamentals are key elements that constitute amature science. The physical and biological sci-ences have reached maturity. The psychologicalsciences have not. Instead, students of psychol-ogy are given choices to be or not to be radicalbehaviorists, cognitive psychologists, evolu-tionary psychologists, social constructivists,feminists, physiological psychologists, or psy-chodynamic psychologists, among others. Thelack of a shared, general understanding has hadunfortunate consequences. Paradigms are de-fined against one another, and epistemologicaldifferences justify the dismissal of insights


gleaned from other approaches. The result hasbeen a fragmented field and a gulf between thenatural and social sciences.

This analysis suggests that the fragmentationthat currently characterizes the field of psychol-ogy is unnecessary. Instead, through the use ofthe ToK System as a meta-theoretical frame-work, a coherent unified theory of psychology ispossible. With it, the truth stands a genuinechance of emerging.

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Received October 17, 2001Revision received March 22, 2002

Accepted March 25, 2002 �

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The ToK and Unification of Psych

Documents

unied psychology

diversity of psychology

unied theory of psychology

review of general psychology

soft psychology theories

clinical psychology

greater unication

science of life