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of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Scientific explanation
Christian Wüthrich
http://philosophy.ucsd.edu/faculty/wuthrich/
145 Philosophy of Science
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of the D-N model
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Explanation as purpose of science
some believe that science must deliver explanation of
whysomething happens—over and above description of whathappens or
prediction of what will happenassume we have a theoryproblem of
explanation may not be independent from problem ofevidence (What is
it to have evidence to believe in a theory?)explanatory inference:
inference from set of data to hypothesisthat would explain
datageneral goal: give individually necessary and jointly
sufficientconditions which a scientific explanation must
satisfylogical empiricism: covering-law model of explanation
Christian Wüthrich Topic 4
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The basic ideaSome detailsThe big picture
Hempel and Oppenheim (1948)
Carl G Hempel (1905-1997), my academicgrandfather
explanandum: that which is to be explained
explanans: that which explains
“By the explanandum, we understand thesentence describing the
phenomenon to beexplained (not that phenomenon itself); bythe
explanans, the class of those sentenceswhich are adduced to account
for thephenomenon.” (p. 152)
explain = show how to derive by logicalargument
premises (= explanans), conclusion (=explanandum)
Christian Wüthrich Topic 4
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of the D-N model
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unification
The basic ideaSome detailsThe big picture
D-N (‘deductive-nomological’) model of explanation
‘nomos’ = (Greek) law
(1) L1, ..., Ln (general laws of nature)(2) C1, ..., Cm
(particular facts)
(3) E (explanandum)
⇒ not much difference between explanation and prediction!
Christian Wüthrich Topic 4
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Van Fraasen’s pragmatic approach to explanationKitcher and
unification
The basic ideaSome detailsThe big picture
Conditions of adequacyAn argument of the form of the H-O scheme
qualifies as scientificexplanation if (among others) the following
conditions are satisfied:
1 The explanandum follows deductively from the propositions
inthe explanans.
2 All propositions of the explanans are true.
3 The explanans contains at least one proposition expressing
ageneral law of nature.
4 The explanandum does not follow from the non-nomological
(=non-lawful) propositions of the explanans alone.
5 The laws in the explanans are not only true, but also in fact
lawsof nature according to our best science.
The first two conditions can be seen as the ‘deductive’ part,
andconditions 3 through 5 as the ‘nomological’ part of the
explanation.
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
The basic ideaSome detailsThe big picture
The role of lawsObviously, laws do important explanatory
work—but just what is alaw?
first pass: true generalization
need to distinguish those that are accidentally true from
‘laws’
example of accidental truth: ‘All members of the
GreensburySchool Board for 1964 are bald’, ‘All fruits in the
garden areapples’
example of law: ‘All gases expand when heated under
constantpressure’
Hempel: ‘counterfactual support’ is diagnostic of lawhood,
butphilosophically hard to capture
⇒ notion of law has proved ‘highly recalcitrant’ (1965, p.
338)second pass: law = true, exceptionless generalization
describingregularity PLUS some additional, yet unspecified
conditions
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
The basic ideaSome detailsThe big picture
The dispensability of a general analysis of laws
DN-model of explanation does not depend upon our ability
toformulate a general account of laws of nature, so long as we
canagree which statements qualify as laws
⇒ no criteria, condition, explication of lawhood
requiredImportant: that there is a law in the explanans, but not
why thestatement at stake is a law
Problem: what to do in less clear cases, such as Mendel’s law
ofsegregation, which has exceptions
Note: we are not allowed to infer from our intuition that
astatement does explanatory work that it is a law, that would
beunjustifiedly circular
Problem: according to some philosophers (e.g. Woodward)many
generalizations from special sciences may well doexplanatory work,
but not qualify as laws
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
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unification
The basic ideaSome detailsThe big picture
Hempel 1962: ‘Hierarchy of covering laws’
particular fact [this stone dropped just now falls...]⇓
class of particular phenomena [stones dropped fall towards
Earth’scenter]⇓
empirical generalization [Galileo’s law of free fall]⇓
comprehensive theories [Newtonian mechanics]⇓
more comprehensive theories [general relativity]
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
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The basic ideaSome detailsThe big picture
⇒ increase in breadth and depth of scientific understanding
breadth: new principles cover broader range of phenomena
depth: original empirical laws seen as holding only
approximately orwithin certain limits
(Often) causal explanations are deductive-nomological in
character,but there are D-N explanations which aren’t causal (e.g.
subsumptionof Kepler’s laws under Newtonian mechanics, temporal
order may bedifferent)
{Causal explanations} ⊂ {D-N explanations}
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
The D-N model as unnecessaryThe D-N model as insufficient
Difficulties of the D-N model
The difficulties come in two broad categories:
D-N model is not necessary, i.e. there are sets of
statementsthat clearly are explanations but do not qualify as
explanationsaccording to the D-N model⇒ conditions are too
narrow
D-N model is not sufficient, i.e. there are sets of statements
thatqualify as explanations according to the D-N model yet onewould
not normally think of them as explanatory⇒ conditionsare too
broad
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
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Van Fraasen’s pragmatic approach to explanationKitcher and
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The D-N model as unnecessaryThe D-N model as insufficient
The D-N model as unnecessary
1 probabilistic explanations seem important in medicine,
genetics,quantum mechanics, statistical physics... yet D-N model
can’taccount for them
2 Michael Scriven (1962): statement ‘The impact of my knee onthe
desk caused the tipping over of the inkwell’ should count
asexplanatory although it does not involve a law
Christian Wüthrich Topic 4
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The D-N model as unnecessaryThe D-N model as insufficient
(1) Probabilistic explanation (I-S model)Probabilistic
explanations: not deductively valid argument asdemanded by D-N
model
⇒ inductive-statistical explanations (I-S model)
Two features:1 laws of probabilistic-statistical form such as
‘Smoking leads to
lung cancer’2 inference is not deductively valid, only
‘inductive’
I-S model is natural extension of D-N model because of
nomic expectability: a phenomenon is explained if it is
shownthat it is to be rationally expected, given the
particularcircumstances and the relevant laws
deflationist account of causation: Humean regularity theory
ofcausation
Christian Wüthrich Topic 4
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The D-N model as unnecessaryThe D-N model as insufficient
(1) Fi (in case i, factors F were realized)(2) p(O, F ) is very
high (law of probabilistic form)
(3) Oi (instance i under consideration has outcome of typeO)
Important: (1) and (2) make (3) very likely rather than
deductivelycertain (indicated by double line)
likelihood: relation (capable of gradation) between
statements—notkinds of occurrences as in the probabilistic law;
‘strength of inductivesupport’, ‘degree of rational
credibility’
Christian Wüthrich Topic 4
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Van Fraasen’s pragmatic approach to explanationKitcher and
unification
The D-N model as unnecessaryThe D-N model as insufficient
(2) Self-admitted limitation of D-N model
formulation may be incomplete or elliptic (omit mention of
certainlaws or facts), but gaps can readily be filled in
partial explanation: complete grounds for expecting that
someevent or other of a certain class will occur, but nothing
aboutwhich one exactly
actual explanation are always partial in this respect
becauseparticular event has infinitely many different aspects, not
all ofwhich can be accounted for by finite set of
explanatorystatements
explanation sketch: even more cursory
Christian Wüthrich Topic 4
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The D-N model as unnecessaryThe D-N model as insufficient
Scriven’s example reconstructed
(from Woodward, 2003, Section 2.4)
1 “Whenever knees impact tables on which an inkwell sits
andfurther conditions K are met (where K specifies that the
impactis sufficiently forceful, etc.), the inkwell will tip over.
(Referenceto K is necessary since the impact of knees on table
withinkwells does not always result in tipping.)
2 “My knee impacted a tables on which an inkwell sits and
furtherconditions K are met.
3 “The inkwell tips over.”
Christian Wüthrich Topic 4
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Van Fraasen’s pragmatic approach to explanationKitcher and
unification
The D-N model as unnecessaryThe D-N model as insufficient
The D-N model as insufficient: causationIf explanans and
explanandum don’t stand in the relevant causalrelation,
insufficiency worries arise:
1 Retrodiction: position of planet today and the laws of
celestialmechanics don’t explain the plant’s position yesterday
2 Common cause: the falling barometer and the laws ofmeteorology
don’t explain the incoming low-pressure front;neither do the yellow
fingers and the ‘laws of medicine’ explainthe lung cancer
3 Asymmetry (Sylvain Bromberger 1966): case of flagpole
andshadow
General: Problems concerning causal relations point
topossibility that explanation and prediction may not be on a
par
Hempel’s reply: if D-N model allows explanations to run in
twodirections, both directions must really be OK
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
The D-N model as unnecessaryThe D-N model as insufficient
The D-N model as insufficient: irrelevance
Irrelevance (Wesley Salmon, 1971):
(1) All males who take birth control pills regularly fail to
getpregnant.(2) John Jones is a male who has been taking birth
controlpills regularly.
(3) John Jones fails to get pregnant.
These arguments indicate that we may need additional conditions,
i.e.that the D-N model only offers necessary, but insufficient
conditions.
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
The D-N model as unnecessaryThe D-N model as insufficient
Recent directions in scientific explanation
1 (van Fraassen) pragmatic account of explanation2 (Kitcher,
Friedman) explanation in terms of unification:
explanation is matter of connecting diverse set of facts
byconnecting them under a set of basic patterns and principles
3 (Nagel) explanation in terms of reduction: explaining a
theoryand the phenomena it addresses by ‘reducing’ it to a
morefundamental theory
4 (Salmon) explanation in terms of causation: explaining a
naturalphenomenon is to state its (necessary and) sufficient
causes
5 pluralism about explanation: all of these important types
ofexplanatory relations, and possibly more
6 contextualism with respect to explanation: standards for
goodexplanations depends on context, particularly on sci
disciplineand on historical period
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Contrast classesVan Fraassen’s analysis
Bas van Fraasen’s pragmatic approach to explanationAs defended
in his The Scientific Image (‘The pragmatics of explantion’)
QuestionWhy did Marge marry Homer?
Explanatory requests are not ex-hausted by their syntactic and
seman-tic expression:
(a) Why did Marge marry Homer?
(b) Why did Marge marry Homer?
(c) Why did Marge marry Homer?
What is shared by the three questionsis their ‘topic’.
Christian Wüthrich Topic 4
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Contrast classesVan Fraassen’s analysis
The relevance of the relevant constrast class
These different explanatory requests can be thought of as
requests tobe told why a particular ‘contrast class’ can be
excluded:
(a) ⇒ {Maude marries Homer, Luann marries Homer,...,
Margemarries Homer,...}
(b) ⇒ {Marge has a fling with Homer, Marge completely
disregardsHomer,..., Marge marries Homer,...}
(c) ⇒ {Marge marries Ned, Marge marries Kirk,..., Marge
marriesHomer,...}
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Contrast classesVan Fraassen’s analysis
Van Fraassen’s analysis of explanationCharacterization
(Explanation, van Fraassen style)
An explanation consists of a question and an answer. The
question isan ordered triple consisting of a topic Fab, a contrast
class{Fab, Fac, Fad , ...}, and a ‘relevance relation’ R:
Q (why is it the case that Fab?) = 〈Fab, {Fab, Fac, Fad , ...},
R〉
where Fab expresses that a and b stand in the binary relation F
. Thetopic Fab must be true, and the other possibilities in the
contrast class(Fac, Fad,...) didn’t in fact occur. An answer A then
“explains Q if, inlight of the background knowledge of the
inquirer, there is somerelationship between A and the topic, Fab,
and the rest of the contrastclass (Fac, Fad, etc.) which excludes
or prevents the occurrence ofthe rest of the contrast class, and
assures the occurrence of the topic,Fab... van Fraassen calls this
relationship between A and the topicand the contrast class ‘the
relevance relation’.” (Rosenberg, 55)
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Contrast classesVan Fraassen’s analysis
Van Fraassen’s analysis of explanationCharacterization
(Explanation, van Fraassen style)
An explanation consists of a question and an answer. The
question isan ordered triple consisting of a topic Fab, a contrast
class{Fab, Fcb, Fdb, ...}, and a ‘relevance relation’ R:
Q (why is it the case that Fab?) = 〈Fab, {Fab, Fcb, Fdb, ...},
R〉
where Fab expresses that a and b stand in the binary relation F
. Thetopic Fab must be true, and the other possibilities in the
contrast class(Fcb, Fdb,...) didn’t in fact occur. An answer A then
“explains Q if, inlight of the background knowledge of the
inquirer, there is somerelationship between A and the topic, Fab,
and the rest of the contrastclass (Fcb, Fdb, etc.) which excludes
or prevents the occurrence ofthe rest of the contrast class, and
assures the occurrence of the topic,Fab... van Fraassen calls this
relationship between A and the topicand the contrast class ‘the
relevance relation’.” (Rosenberg, 55)
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Contrast classesVan Fraassen’s analysis
Van Fraassen’s analysis of explanationCharacterization
(Explanation, van Fraassen style)
An explanation consists of a question and an answer. The
question isan ordered triple consisting of a topic Fab, a contrast
class{Fab, Gab, Hab, ...}, and a ‘relevance relation’ R:
Q (why is it the case that Fab?) = 〈Fab, {Fab, Gab, Hab, ...},
R〉
where Fab expresses that a and b stand in the binary relation F
. Thetopic Fab must be true, and the other possibilities in the
contrast class(Gab, Hab,...) didn’t in fact occur. An answer A then
“explains Q if, inlight of the background knowledge of the
inquirer, there is somerelationship between A and the topic, Fab,
and the rest of the contrastclass (Gab, Hab, etc.) which excludes
or prevents the occurrence ofthe rest of the contrast class, and
assures the occurrence of the topic,Fab... van Fraassen calls this
relationship between A and the topicand the contrast class ‘the
relevance relation’.” (Rosenberg, 55)
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Contrast classesVan Fraassen’s analysis
Some comments
An explanation is scientific just in case “it employs a
relevancerelation fixed by the theories and experimental methods
thatscientists accept at the time the explanation is offered.”
(ibid.,55f)
⇒ This pragmatic approach cannot independently identify what
isdistinctive of scientific explanations (vis-à-vis
non-scientificones).
On the other hand, it can deal with the counterexamples
thatafflict the D-N model, and can mark the distinction between
trueexplanations (e.g. using QM to explain why square peg
doesn’tfit round hole) and good ones (e.g. using Newtonian
physics).
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
Philip Kitcher (*1947)
studied mathematics at Cambridge,philosophy/HPS at Princeton,
where heobtained his PhDtaught at Vassar College, U of Vermont,U of
Minnesota, UCSD, Columbiaphil of mathematics, general phil sci,phil
of biologyrecently: “ethical and politicalconstraints on scientific
research, theevolution of altruism and morality, andthe apparent
conflict between scienceand religion” (from his website)
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
Logical empricism’s unofficial story unveiled
Philip Kitcher, ‘Explanatory unification’, Philosophy of Science
48 (1981): 507-531.
Philip Kitcher, ‘Explanatory unification and the causal
structure of the world’, reprinted in Balashov andRosenberg (eds.),
Philosophy of Science: Contemporary Readings, London and New York
(2002), 71-91.
Kitcher makes two claims:1 Hempel’s covering law model of
explanation is fraught with
difficulties2 but this is only the ‘official’ view of logical
empiricism,
there’s another one: the ‘unofficial’ story
involvingunification
evidence for the second claim: next slide
Kitcher takes upon himself the task of developing and
defendingthis unofficial story
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
Hempel: (Hempel 1966, p. 83; cf. also Hempel 1965, pp. 345,
444)
“What scientific explanation, especially theoreticalexplanation,
aims at is... an objective kind of insight that isachieved by a
systematic unification, by exhibiting thephenomena as
manifestations of common, underlyingstructures and processes that
conform to specific, testable,basic principles.”
Feigl: (Feigl 1970, p. 12)
“The aim of scientific explanation throughout the ages hasbeen
unification, i.e. the comprehending of a maximum offacts and
regularities in terms of a minimum of theoreticalconcepts and
assumptions.”
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
Two desiderata for an account of scientific explanation
A theory of explanation should...
1 “show how scientific explanation advances our
understanding”(508)
2 “enable us to judge the adequacy of the defense” of
embryonictheories “by appeal to their explanatory power”
(ibid.)
Kitcher claims that the covering law model satisfies neither of
thesedesiderata, unlike his model based on unification.
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
What is an explanation?
Definition (Explanation à la Kitcher)
“[A]n explantion is an ordered pair consisting of a proposition
and anact type. The relevance of arguments to explanation resides
in thefact that what makes an ordered pair (p, explaining q) an
explanationis that a sentence expressing p bears an appropriate
relation to aparticular argument.” (509)
“More colloquially, my project will be that of deciding when
anargument explains why its conclusion is true.” (510)
One more remark: Kitcher thinks that history of science
showsthat explanatory power of a scientific theory must
“involverecognition of a virtue over and beyond considerations
ofsimplicity and predictive power.” (512)
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
The general set-up
set of accepted sentences K
“The general problem... is that of specifying E(K ),
theexplanatory store over K , which is the set of
argumentsacceptable as the basis for acts of explanation by those
whosebeliefs are exactly the members of K .” (512)
Answer given by the ‘unofficial view’: “for each K , E(K ) is
the setof arguments which best unifies K .” (ibid.)
⇒ articulate this answer!
start by looking at two historical examples: the
Newtonianprogram, the reception of Darwin’s theory of evolution
Christian Wüthrich Topic 4
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of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
The Newtonian program of dynamic corpuscularianism
Characterization (Dynamic corpuscularianism)
Newton showed how one can infer the motion of bodies from
aknowledge of the forces acting upon them, so many C18
Newtoniansattempted to pursue this idea by postulating inter-atomic
forces inorder to explain phenomena they believed arose from the
motion ofatoms. “In searching for force laws analogous to the law
of universalgravitation, Newton’s successors were trying to
generalize the patternof argument presented in Principia, so that
one ‘kind of reasoning’would suffice to derive all phenomena of
motion.” (514)
program remained popular so long as there was promise
ofunification
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
Kitcher’s lessons
From this historic example and from the reception of Darwin’s
theoryof evolution, Kitcher draws three morals:
1 certain programs have been favoured not because of
theirpredictive power–which they were yet to actualize–, but
becauseof their explanatory promise;
2 the explanatory power of these programs is closely tied
tounification;
3 there are particular features of the theories/programs that
“aretaken to support their claims to unification.” (512)
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
Kitcher’s theory of explanation: terminology
general argument pattern: roughly, a schematic argument plus
fillinginstructions
stringent argument patterns: roughly, patterns containing
somenonlogical terms (constrained by rules of substitution) and
exhibitingsimilar logical structure (subject to conditions of
similarity)
Goal, as stated before: specify, in a principled way, which set
ofarguments E(K ) best unifies or systematizes K
lesson from historic examples: unification is achieved by using
similararguments in derivation of many sentences of K
Σ is a set of arguments, Π is a set of argument patterns
Σ is generated by Π if each argument in Σ is an instantiation of
someargument in Σ
conclusion set C(Σ) of a set of args Σ: set of sentences which
occur asconclusions of some argument in Σ
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
More terminology and a pictureAmong all the set of
argumentpatterns Π of Σ, select the onewith the greatest unifying
power(this set is called the basis B forΣ.Among all the bases Bi ,
selectthe one with the greatestunifying power.If Bk is this basis,
thenE(K ) = Σk .On first pass: unifying power ofBi with respect to
K variesdirectly with size of C(Σ), variesdirectly with stringency
ofpatterns in Bi , varies inverselywith size of Bi
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
Two corollaries
Corollary (A)
“Let Σ, Σ′ be sets of argument which are acceptable relative to
K andwhich meet the following conditions: (i) the basis of Σ′ is as
good asthe basis of Σ in terms of the criteria of stringency of
patterns, paucityof patterns, presence of core patterns, and so
forth. (ii) C(Σ) is aproper subset of C(Σ′). Then Σ 6= E(K ).”
(522)
Corollary (B)
“Let Σ, Σ′ be sets of argument which are acceptable relative to
K andwhich meet the following conditions: (i) C(Σ) = C(Σ′) (ii) the
basis ofΣ′ is a proper subset of the basis of Σ. Then Σ 6= E(K ).”
(ibid.)
Christian Wüthrich Topic 4
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Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
Reminder: two major problems for the D-N model
1 Asymmetry
2 Irrelevance
Christian Wüthrich Topic 4
-
Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
(a) Solving Asymmetry
Whoever accepts that the specification of the period (together
withlaws about pendula) is explanatory of the length of a pendulum,
canbe hit with a dilemma:
1 either two patterns of argument must be adopted because
adifferent pattern will be needed in the explanation of the length
ofnon-swinging bodies
⇒ violation of Corollary B2 or only one pattern is adopted, but
the relevant discourse will be
limited to cases of swinging pendula
⇒ violation of Corollary A
⇒ Either way, the candidate explanation does not live up to
thestandards as set by the unificationist account and
shouldtherefore not be considered an explanation.
Christian Wüthrich Topic 4
-
Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
(b) Solving Irrelevance
Whoever accepts that the dissolving of the hexed salt is
explained byan appeal to its being hexed, can be hit with a
dilemma:
1 either two patterns of argument must be adopted because
adifferent one will be needed for unhexed salt
⇒ violation of Corollary B2 or only one pattern is adopted, but
the relevant discourse will be
limited to cases of hexed salts
⇒ violation of Corollary A
⇒ Either way, the candidate explanation does not live up to
thestandards as set by the unificationist account and
shouldtherefore not be considered an explanation.
Christian Wüthrich Topic 4
-
Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
My challenge to Kitcher
Consider once again the case of John’s failure to get
pregnantafter having regularly taken birth control pills.
⇒ If it’s the regular taking of birth control pills that
explains John’sfailure to get pregnant, then we can use the same
argumentpattern (and it should be considered stringent according
toKitcher’s conditions).
⇒ more unified explanatory pattern (same in males and
females),in concordance with the demands of Corollary B
It seems as if any explanation for males that would differ
fromthe ones offered for females would decrease in unifying
power.
Or is this a case of spurious explanation?
Christian Wüthrich Topic 4
-
Hempel’s deductive-nomological model of explanationDifficulties
of the D-N model
Van Fraasen’s pragmatic approach to explanationKitcher and
unification
Logical empricism’s unofficial story unveiledSome general
remarks and a lesson from historyKitcher’s theory of
explanationDealing with objections
Spurious unification
Problem: anything can be derived from it conjoined with
Boyle’slaw
Answer: this would be a spurious unification
Definition (Spurious unification)
“If the filling instructions associated with a pattern P could
bereplaced by different filling instructions, allowing for the
substitution ofa class of expressions of the same syntactic
category, to yield patternP ′ and if P ′ would allow the
derivations of any sentence, then theunification achieved by P is
spurious.” (527f)
idea: genuinely unifying patterns should not be able
toaccommodate all conclusions
Christian Wüthrich Topic 4
Hempel's deductive-nomological model of explanationThe basic
ideaSome detailsThe big picture
Difficulties of the D-N modelThe D-N model as unnecessaryThe D-N
model as insufficient
Van Fraasen's pragmatic approach to explanationContrast
classesVan Fraassen's analysis
Kitcher and unificationLogical empricism's unofficial story
unveiledSome general remarks and a lesson from historyKitcher's
theory of explanationDealing with objections