Neuro 95: Foundations of Neuroscience History & Philosophy Module

1. Neuro 95:Foundations of NeuroscienceHistory & Philosophy Module Brian Keeley Philosophy, Pitzer College Office: Broad Hall 107 Dion Scott-Kakures Philosophy, Scripps College Office: Humanities Bldg #215 Lecture 2

2. Housekeeping • Assessment: An in-class exam on last day of module (be able to identify and talk about the significance of some quotations & discuss some of the philosophical arguments we’ll be considering)

3. Today’s Reading • Patricia Churchland, "Functionalist Psychology"

4. Reductionism vs. Antireductionism • Neuroscience, Psychology, Physics, Economics are all sciences (purveyors of different theories with different ontologies/ taxonomies/vocabularies) • Question: What is the relationship between these theories (especially as they apply to the exact same region of space-time; e.g., your suitemate)? • “Completed Science”/ “The end of Science”

5. Reductionism vs. … • Reductionists are those who argue that there really is only one, true scientific theory. • Ernest Rutherford(The “Father of Nuclear Physics”):"All science is either physics or stamp collecting”

6. … vs. Antireductionism • Antireductionists are those who argue that theories at different levels are autonomous & independent of one another. • Psychology need not coordinate it’s theory with neuroscience anymore than Economists need to square their theories of inflation with quantum mechanics. • One influential set of arguments for antireductionism comes from the philosophical school known as “Functionalism”

7. … vs. Antireductionism • Jerry Fodor: “It isn't, after all, seriously in doubt that talking (or riding a bicycle, or building a bridge) depends on things that go on in the brain somewhere or other. If the mind happens in space at all, it happens somewhere north of the neck. What exactly turns on knowing how far north? It belongs to understanding how the engine in your auto works that the functioning of its carburettor is to aerate the petrol; that's part of the story about how the engine's parts contribute to its running right. But why (unless you're thinking of having it taken out) does it matter where in the engine the carburettor is? What part of how your engine works have you failed to understand if you don't know that?” (From Times Literary Supplement)

8. 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

9. So what is “reduction”? • What’s at issue here is “theories” (not phenomena) • Theories—that is, structured sets of linguistic statements—are what either do or don’t get reduced. • And, traditionally, it has been argued that one theory (TR) is reduced by another theory (TB) when you can logically derive TR from TB.

10. So what is “reduction”? • So, we say that modern chemistry is reduced by modern physics because the laws ofchemistry(how molecules bind or don’t bind, how acid works, etc.) can be deduced from the laws ofphysics(the behavior of atoms and electrons, etc.)

11. S1 S2 Law in TR Bridge Law Bridge Law P1 P2 Law in TB Or, for the visually-minded The Explanandum or Explananda (pl) The Explanans

12. Functionalism: Levels of explanation

13. 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)

14. 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.)

15. Hardware & Software • Themindis thesoftwarethat runs on thehardwareof thebrain.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. • Computerengineering 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).

16. Levels • Example by way of analogy: • Garry Kasparov vs. Deep Blue

17. 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”

18. 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”?

19. 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

20. Multiple realization • An implication of the “computer metaphor” • The mapping from mind to physical substrate is one-to-many. One and the same mental state—being in pain, believing George W. Bush is president, etc.—can be realized in more than one physical way. • In a trivial fashion, each of us can be said to have the same beliefs, even though each of our brains is physically unique.

21. Multiple realization • More extreme cases: • Left vs. Right hemispherectomy cases • Human pain vs. Octopi pain • The possibility of artificial intelligence • Functionists take the phenomenon of multiple realization to entail that mental phenomena cannot be theoretically reduced to brain phenomena.

22. S1 S2 Law in TR P1 P2 P3…Pn P’1 P’2 …P’m Many Disparate Laws in TB Fodor’s Picture Wildly Disjunctive