Minds and Machines

1. Minds and Machines Summer 2011 Thursday, 07/28

4. Paper • Have a clear thesis and a clear argument-strategy. • Have a simple, obvious structure. • Each part of the paper (paragraph, sentence) should be doing something essential to support the thesis. (if you can remove it and still establish the thesis, don’t hesitate to do so.) • It should be absolutely clear what each part (paragraph, sentence) is doing. • Use simple prose, avoid ornamentation. • Break up long sentences. • Read Jim Pryor’s guidelines!

5. Arguments for LOTH: Cog-Sci(“Only Game in Town” argument) • One of the first, main arguments Fodor introduced in his book The Language of Thought. • Our best scientific theories of cognitive processes (e.g. vision, learning, decision-making) appeal to information processing. • Information processing requires an appropriate computational medium, some set of structured representations over which the computations could be made.

6. Arguments for LOTH: Productivity • Adults who speak a natural language can understand sentences they have never heard uttered before. • Understanding a sentence is to entertain the thought/proposition it expresses. • So there are, in principle, infinitely many thoughts that we are capable of entertaining. • But this unbounded capacity must be realized by finite means. (Since we’re finite beings, storing an infinite number of representations in our heads is out of the question.)

7. Example of Productivity • The dog bit the girl. • The dog bit the girl and she cried. • The big dog bit the girl and she cried. • The big dog bit the girl and she cried loudly. • The big dog bit the girl who was misbehaving and she cried loudly. • The big dog with the surprisingly developed moral instincts bit the girl who was misbehaving and she cried loudly. • The big dog with the surprisingly developed moral instincts bit the girl who was misbehaving and she cried loudly and ran to her father who praised and petted the dog.

8. Arguments for LOTH: Productivity • How could this capacity be explained? • LOTH offers a straightforward explanation. • LOT representations have a combinatorial syntax and semantics. • Structurally complex (molecular) representations are systematically built up out of structurally simple (atomic) constituents. • The rules for symbol manipulation allow us to generate a limitless range of molecular representations. (We already saw how this works in the case of formal systems)

9. Arguments for LOTH: Systematicity • Imagine learning a language by memorizing a huge phrasebook that just tells you the meaning of individual sentences. • There is nothing to prevent you from learning how to say ‘John loves the girl’ without learning how to say ‘the girl loves John.’ • In fact, that is exactly how some tourist booklets are made. You might learn from a phrase book how to say ‘I'd like to have a cup of coffee’ in Russian without knowing how to say/understand absolutely anything else in Russian.

10. Arguments for LOTH: Systematicity • In contrast, a speaker's knowledge of her native language is systematic. • E.g. we don't find speakers who know how to express in their native language the fact that John loves the girl but not the fact that the girl loves John. Same goes for: Bill is boring and Fred is funny and Fred is funny and Bill is boring. • This shows that learning one's native language cannot be understood on the phrase book model.

11. Arguments for LOTH: Systematicity • Instead, as we know, native speakers learn the grammar and vocabulary of their language. • If you have a vocabulary, the grammar tells you how to combine systematically the words into sentences. So if you know how to construct a particular sentence out of certain words, you automatically know how to construct many others.

12. Arguments for LOTH: Systematicity • Now, to understand a sentence is just to think the thought/proposition it expresses. • So if the ability to understand a sentence is systematically connected to the ability to understand many others, then (similarly) the ability to think a thought is systematically connected to the ability to think many others. • But what’s the explanation of this latter fact? Why is it that we can’t form certain thoughts without having the ability to form certain others?

13. Arguments for LOTH: Systematicity • The explanation LOTH gives mirrors the explanation of linguistic systematicity. • It’s just that instead of rules for manipulating linguistic representations (words and sentences), you have rules for manipulating mental representations (realized as events and states in the brain). • This seems to be the only explanation that doesn’t make the systematicity of thought a miracle, and thus supports LOTH.

14. Arguments for LOTH: Inferential Coherence • Unlike the former arguments that focus on our ability to form thoughts, this one focuses on our ability to move between thoughts. • We don’t find normal human minds that are always prepared to infer P from P&Q&R but not infer P from P&Q. • Inferential coherence (with respect to R): Given that a system can draw a particular inference that is an instance of a certain logical rule, R, the system can draw any inferences that are instances of R. • LOTH accounts for the fact that many human thought processes are inferentially coherent by claiming that these processes are sensitive to the form (e.g. shape) of our mental representations.

15. Churchland • There are no inner states that closely match our talk of propositional attitudes, i.e. there are no beliefs, hopes, desires, and so on. • As science progresses, we will drop talk of such entities and adopt an entirely new, scientific way of talking about our psychology.

16. Churchland “We need an entirely new kinematics and dynamics with which to comprehend human cognitive activity. One drawn, perhaps, from computational neuroscience and connectionist AI. Folk psychology could then be put aside in favor of this descriptively more accurate and explanatorily more powerful portrayal of the reality within.”

17. Churchland Our common-sense psychology is inadequate because: • It works only in a limited domain (some aspects of the mental life of normal, human agents). It doesn’t illuminate creativity, memory, mental illness, infant and animal thoughts, and many other mental phenomena. • There haven’t been any developments in the theory for the last 2500 years!

18. Churchland 3. Its origins and evolution are shaky. If you look at most unscientific folk theories (e.g. of astronomy, physics) you quickly discover that most of them were completely wrong. 4. It doesn’t seem to fit in with the rest of our scientific picture of ourselves. There is no sign yet of any systematic translation of our talk of propositional attitudes to the language of of neuroscience and physics.

19. Elimination vs. Reduction • Reduction = Identifying the objects and properties of some domain with (configurations) of objects and properties of another, more fundamental, domain. Examples: Water = H20, Heat = mean kinetic energy of molecule movements, Material Objects = Collections of Molecules, genes = DNA molecules.

20. Reduction vs. Elimination • Elimination (from ontology): Denying the reality/existence of the objects and properties of some domain. Examples: Witches, spirits, humors, Phlogiston, vital substances, the GreekGods.

21. Reduction vs. Elimination • When it comes to the propositional attitudes: Fodor is a non-reductivist. The identity theorist is a reductivist. Churchland is an eliminativist.

22. Questions for Churchland • If there are no beliefs, desires, and so on, how come common-sense psychology works so well? • If we abandon PA talk, wouldn’t we have to abandon talk about more basic notions such as reference and truth? And could we really continue doing (neuro)science without using the concept of truth? • Isn’t it always reasonable to believe the theory that has the most predictive and explanatory success. At present, there’s no theory that’s even remotely close to common sense psychology. So isn’t it reasonable to accept common-sense psychology by default? • Wasn’t the atomic theory also stagnant for 2500 years? And didn’t Fodor point to a way to make developments in PA-psychology? • Do the examples of alternatives to PA-psychology that Churchland gives REALLY make sense?

23. What is Dennett? • Facts about belief, desire, and so on are only facts about the tendency of some object (e.g. a person, a car) to succumb to an interpretative approach that treats the object as a rational agent and ascribes it beliefs and desires. • It’s hard to put a label on this position.

24. Dennett • On the face of it, Dennett’s position seems counter-intuitive. It’s hard to believe that my having certain thoughts depends on anyone’s finding it useful to attribute these thoughts to me! • Also, it may seemunclear how his view allows for PAs to have causal role. (If they don’t have causal role, it seems that his view is only superficially different from Churchland’s.)

25. Dennett • The difference between Dennett and Churchland is subtle. • They both doubt that neuroscience will be compatible with Fodor’s idea of mental symbols or representations that behave (more or less) like desires and beliefs. They agree on what is likely to be found “in the head”. • But Dennett holds that beliefs are as real and legitimate as abstractions “in good standing”: centers of gravity, economic depressions, voices, and so on. These things are less real than concrete particulars, but real nevertheless. (this seems to require accepting that there are multiple grades of reality, which is pretty radical (contrast: geology, biology, etc) • On the other hand, Churchland holds that beliefs are as unreal as the concrete particulars that are posited by misguided theories.

26. Dennett • This still leaves the question of causation. To have any sort of reality, it seems that beliefs would have to cause behavior and other mental states. • But how can they do so if there is no single state of belief in the brain? • To answer the question Dennett appeals to “scattered causation”. The kind of causation appealed to in sociology, economics, politics, and so on.