Neuro 95:Neuro 95:Foundations of NeuroscienceFoundations of NeuroscienceHistory & Philosophy ModuleHistory & Philosophy Module
Brian KeeleyBrian KeeleyPhilosophy, Pitzer CollegePhilosophy, Pitzer College
Office: Broad Hall 107Office: Broad Hall 107
Lecture 2
Dion Scott-KakuresDion Scott-KakuresPhilosophy, Scripps CollegePhilosophy, Scripps College
Office: Humanities Bldg #215Office: Humanities Bldg #215
HousekeepingHousekeeping
Assessment: Assessment: An An in-class exam in-class exam on last on last day of module (be able to identify and day of module (be able to identify and talk about the significance of some talk about the significance of some quotations & discuss some of the quotations & discuss some of the philosophical arguments we’ll be philosophical arguments we’ll be considering) considering)
Today’s ReadingToday’s Reading Patricia ChurchlandPatricia Churchland, , "Functionalist "Functionalist
Psychology"Psychology"
Reductionism vs. AntireductionismReductionism vs. Antireductionism Neuroscience, Psychology, Physics, Neuroscience, Psychology, Physics,
Economics are all sciences Economics are all sciences (purveyors of (purveyors of different theories with different ontologies/ different theories with different ontologies/ taxonomies/vocabularies)taxonomies/vocabularies)
Question:Question: What is the relationship What is the relationship between these theories (especially as between these theories (especially as they apply to the exact same region of they apply to the exact same region of space-time; e.g., your suitemate)?space-time; e.g., your suitemate)?
““Completed Science”/ “The end of Completed Science”/ “The end of Science”Science”
Reductionism vs. …Reductionism vs. … Reductionists are those who argue that Reductionists are those who argue that
there really is only one, true scientific there really is only one, true scientific theory.theory.
Ernest RutherfordErnest Rutherford (The “Father of Nuclear (The “Father of Nuclear
Physics”):Physics”): "All science is either physics or "All science is either physics or stamp collecting”stamp collecting”
… … vs. Antireductionism vs. Antireductionism Antireductionists are those who argue Antireductionists are those who argue
that theories at different levels are that theories at different levels are autonomous & independent of one autonomous & independent of one another.another.
Psychology need not coordinate it’s Psychology need not coordinate it’s theory with neuroscience anymore than theory with neuroscience anymore than Economists need to square their theories Economists need to square their theories of inflation with quantum mechanics.of inflation with quantum mechanics.
One influential set of arguments for One influential set of arguments for antireductionism comes from the antireductionism comes from the philosophical school known as philosophical school known as “Functionalism”“Functionalism”
… … vs. Antireductionism vs. Antireductionism Jerry Fodor:Jerry Fodor: “ “It isn't, after all, seriously in doubt that It isn't, after all, seriously in doubt that
talking (or riding a bicycle, or building a bridge) depends talking (or riding a bicycle, or building a bridge) depends on things that go on in the brain somewhere or other. If on things that go on in the brain somewhere or other. If the mind happens in space at all, it happens somewhere the mind happens in space at all, it happens somewhere north of the neck. What exactly turns on knowing how north of the neck. What exactly turns on knowing how far north? It belongs to understanding how the engine in far north? It belongs to understanding how the engine in your auto works that the your auto works that the functioningfunctioning of its carburettor is of its carburettor is to aerate the petrol; that's part of the story about how to aerate the petrol; that's part of the story about how the engine's parts contribute to its running right. But the engine's parts contribute to its running right. But why (unless you're thinking of having it taken out) does why (unless you're thinking of having it taken out) does it matter it matter wherewhere in the engine the carburettor is? What in the engine the carburettor is? What part of how your engine works have you failed to part of how your engine works have you failed to understand if you don't know that?” (From understand if you don't know that?” (From Times Times Literary SupplementLiterary Supplement))
Score-card
Sterelny (& Fodor): Functionalist Pat Churchland: Eliminativist
Reductionist (but spends time explaining functionalism. She takes it seriously.)
Lycan: (Homuncular) Functionalist Bechtel, Mundale, Zawidsky, Craver (to be
read during final integrative module): Trying to find new ways of relating neuroscience and psychology
So what is “reduction”?So what is “reduction”?
What’s at issue here is “theories” (not phenomena)What’s at issue here is “theories” (not phenomena) TheoriesTheories—that is, structured sets of linguistic —that is, structured sets of linguistic
statements—are what either do or don’t get reduced.statements—are what either do or don’t get reduced. And, traditionally, it has been argued that one theory And, traditionally, it has been argued that one theory
(T(TRR) is ) is reducedreduced by another theory (T by another theory (TBB) when you can ) when you can
logically derivelogically derive T TRR from T from TBB..
So what is “reduction”?So what is “reduction”?
So, we say that modern chemistry is So, we say that modern chemistry is reducedreduced by modern physics because the by modern physics because the laws oflaws of chemistrychemistry (how molecules bind (how molecules bind or don’t bind, how acid works, etc.) can or don’t bind, how acid works, etc.) can be deduced from the laws ofbe deduced from the laws of physicsphysics (the behavior of atoms and electrons, (the behavior of atoms and electrons, etc.)etc.)
Or, for the visually-mindedOr, for the visually-minded
Law in TLaw in TRR
SS11 SS22
Law in TLaw in TBB
PP11 PP22
BridgeBridgeLawLaw
BridgeBridgeLawLaw
The The ExplanandumExplanandum or or ExplanandaExplananda (pl) (pl)
The The ExplanansExplanans
In the Beginning…There was AI Back in the 1940s, Alan
Turing built one of the first computers, developed the science of computation and along the way, invented the science of Artificial Intelligence (AI).
(He also single-handedly won WWII.)
(1912-1954)
Universal Computing His idea: Computers can follow any
definable set of rules for converting inputs into outputs.
This is the notion of a “Universal Computer”. A device that can compute any process that can be formally described
Human, intelligent behavior is just a complicated way of converting inputs into outputs (Humans are very complex information processing machines.)
Hardware & Software
The mind is the software that runs on the hardware of the brain. Psychology figures out the program and AI ports it to a new platform, the digital computer.
(Cognitive) Psychology is the science of that information processing.
Computer engineering is the study of computer hardware
Neuroscience is the study of human hardware (“wetware”?)
AI happens when you set up an artificial info processor (a digital computer) to copy the formal properties of another info processor (a human).
3 Ways to explain Deep Blue’s behavior
Hardware Design Level - wiring diagram of the computer, the transistors and gates, magnetic and electrical states of the machine
Software Design Level - Deep Blue’s computer program
“Folk Psychological” Level - Deep Blue’s “knowledge,” “beliefs,” & “desires”
Some considerations Hardware Design Level - Most
complete explanation, but extremely detailed and difficult to obtain
Software Design Level - Relatively independent of the hardware level (programmers are largely ignorant of the details of hardware). Same software can run on different hardware.
Folk Psychological Level - A lot of predictive power, but is this kind of explanation merely a “useful fiction”?
Can we do the same thing for Kasparov?
Hardware Design Level - The neuronal wiring of his brain, states of his neurotransmitters, etc.
Software Design Level - The information processing of his “cognitive systems” (memory system, perceptual system, etc.)
Folk Psychological Level - His knowledge, beliefs, and desires
Multiple realizationMultiple realization An implication of the “computer An implication of the “computer
metaphor”metaphor” The mapping from mind to physical The mapping from mind to physical
substrate is one-to-many. One and the substrate is one-to-many. One and the same mental state—being in pain, same mental state—being in pain, believing George W. Bush is president, believing George W. Bush is president, etc.—can be realized in more than one etc.—can be realized in more than one physical way.physical way.
In a trivial fashion, each of us can be In a trivial fashion, each of us can be said to have the same beliefs, even said to have the same beliefs, even though each of our brains is physically though each of our brains is physically unique.unique.
Multiple realizationMultiple realization More extreme cases:More extreme cases: Left vs. Right hemispherectomy Left vs. Right hemispherectomy
casescases Human pain vs. Octopi painHuman pain vs. Octopi pain The possibility of artificial The possibility of artificial
intelligence intelligence Functionists take the phenomenon Functionists take the phenomenon
of multiple realization to entail that of multiple realization to entail that mental phenomena cannot be mental phenomena cannot be theoretically theoretically reducedreduced to brain to brain phenomena. phenomena.