Philosophical Foundations of Cognitive Science

1. 11/11/2011 PFCS 1 Philosophical Foundations of Cognitive Science Week 2: Folk Psychology & Eliminativisim

2. 11/11/2011 PFCS 2

3. 11/11/2011 PFCS 3 Sense/Reference �The morning star was beautiful today� �There were too many clouds, I couldn�t see the evening star today� The referent of �the morning star� and �the evening star� turns out to be one and the same thing: the planet Venus The senses of the two phrases are different

4. 11/11/2011 PFCS 4 De Re/De Dicto John believes there are woodchucks in the garden Woodchucks are the same thing as groundhogs John believes there are groundhogs in the garden?

5. 11/11/2011 PFCS 5 This week� So what are propositional attitudes? (What does it mean to ascribe a propositional attitude to someone?) Are they: A common sense way of looking at the world? A window onto the true nature of thought? (LOT � next week) A (pre-)scientific theory about why and how people behave? If a theory, might the theory be wrong?

6. 11/11/2011 PFCS 6 A theory? Prof Jones: �Would you be prepared to give a lecture at my University?� Prof Smith: �Certainly. When?� Prof Jones: �Can you make the afternoon of Tuesday, 31st March?� Prof Smith: �I can. I will get the flight from New York to LA that arrives at 11.00am on the 31st. Can you meet me at the airport?� Prof Jones: �Of course.�

7. 11/11/2011 PFCS 7 Two competing theories Our best developed formal science of middle-sized objects: Newtonian Physics. Good a predicting what happens if Prof. Jones trips at the top of the stairs Bad at predicting where he will be in 3 months time Another theory, that we use all the time without thinking about it: Prof Jones wishes to give a lecture at Caltech. He plans to get the 7.00am flight from NY arriving at LAX at 11.00am. Prof Smith wishes to meet Prof Jones when his flight arrives. He believes that Prof Jones� flight will arrive at 11.00am.

8. 11/11/2011 PFCS 8 Two competing theories Can we predict where these middle sized objects (Prof Smith and Jones) will be in 3 months time? With Newtonian Physics: No! With our folk theory of beliefs and desires: Perfectly? No Really quite well? Yes The best (or only) theory we could realistically use to predict things like this? Maybe Fodor: Yes Churchland: No

9. 11/11/2011 PFCS 9 Folk Psychology �Folk Psychology�? Folk Physics, Folk Chemistry , Folk Biology?? There is something �theory-like�, and correctable, about our commonsense understanding of these domains One example: Folk physics: a moving object not subjected to any external force will eventually come to a halt. Wrong. Physics isn�t like that.

10. 11/11/2011 PFCS 10 Folk Psychology There really are some things called beliefs and desires (intentional realism) I don�t know what they are (not part of my theory) But I do know what they do (what functional role they play) I claim that they relate to each other, and to observable behaviour, by some (rough and ready) laws

11. 11/11/2011 PFCS 11 Folk Psychology Here are some (rough & ready) laws of my theory: If someone gets what they want then, ceteris paribus (all other things being equal) they will be happy If someone is happy then (ceteris paribus), they will smile, walk with a spring in their step, etc. If someone is in pain then they will want to withdraw from or otherwise prevent the occurrence of the painful stimulus If someone wants to do something then (ceteris paribus) they will do it

12. 11/11/2011 PFCS 12 Folk Psychology According to Paul Churchland, this set of laws is exactly what a normal theory looks like (even the ceteris paribus clauses) One example: �A river erodes it outside bank� Implicit ceteris paribus: As long as the outside bank is not made of concrete As long as the river does not freeze over etc., etc.

13. 11/11/2011 PFCS 13 Folk Psychology FP is a theory like any other because we: Have postulated a set of entities Have described the relationships between the entities Have described the observations we can make According to PC, when we say that someone believes something, we are saying that: The entire inter-related framework of beliefs, desires, wishes, wants, intentions, etc. applies to them At the current time, certain things expressed in that framework are true of them This is the normal structure of a scientific theory So FP is (appears to be): �Systematic, speculative & corrigible�

14. 11/11/2011 PFCS 14 Eliminativism Even if FP is a theory, why might we think that it is wrong? �Explanatory failures on an epic scale� Can�t explain (amongst others): the mentally ill creativity imagination sleep & dreams perceptual illusions memory itself

15. 11/11/2011 PFCS 15 Eliminativism �Stagnant for at least 25 centuries�: infertility and decadence (same theory that the ancients had) in fact, not just stagnant, but in retreat (animism) (but cf �Ethnopsychologies�)

16. 11/11/2011 PFCS 16 Eliminativism Ununifiable with the rest of science: The categories of FP stand magnificent and alone There is no sign that FP can be reduced to the natural sciences

17. 11/11/2011 PFCS 17 Eliminativism All the signs are that FP is false, so it should go the way of other false theories alchemy the ether phlogiston etc. Elimination!

18. 11/11/2011 PFCS 18 Anti-Eliminativism FP is indispensable: the abstract nature of FP states (their multiple realizability) means that one cannot replace them with talk of, e.g., neurophysiological states. Churchland's reply: This functionalist move could be used to save alchemy! So it cannot be correct.

19. 11/11/2011 PFCS 19 Anti-Eliminativism FP is normative: It is a characterisation of how we should behave, if we are to behave rationally. It is an ideal. It is a definition of something (rational behaviour), not a theory, so it cannot be false. Churchland�s response: We only think FP is normative because we value the things described by it (rationality) But there still might be another, better, account of what it is to be rational, which does not use the propositional attitudes; we don�t have a good enough handle on what rationality is to be sure.

20. 11/11/2011 PFCS 20 Anti-Eliminativism Horgan & Woodward: �Explanatory failures on an epic scale�? Disputable; FP is successful many theories based on FP are now starting to explain things like mental illness, creativity Moreover: should FP explain all that? (cf optics � the higher level description of light is still correct)

21. 11/11/2011 PFCS 21 Anti-Eliminativism Horgan & Woodward: �Stagnant or in retreat�? Compare ancient theory of mind to Freud (unconscious beliefs and desires) Stagnancy does not imply falsity: The sharp blow caused the pot to break Lack of water caused the camel to die

22. 11/11/2011 PFCS 22 A replacement for FP? So what does Paul Churchland suggest instead of FP as we know it today? Three scenarios. These are not meant to be predictions of the future. They are just meant to show that it might be possible to replace FP with something better after all� A new characterisation of brain states, so much better than FP that everybody starts to use it A new language, framed in terms of the above; it turns out we can learn this � with our general purpose brains � it has different grammar, different semantics, different ideas of true and false, even. Direct brain to brain communication; what you know of other people�s brain is then much better than FP, and there is nothing sentential or propositional about it These are just thought experiments, we will return to a more grounded proposal (championed by Churchland, and most closely related to the first of the above) in week 6: Vector coding in connectionist parallel architectures

23. 11/11/2011 PFCS 23 Reading You might well want to additionally look at: Terence Horgan and James Woodward, �Folk Psychology is Here to Stay�, Ch. 12 of LYCAN (an interesting, clear paper) If you are interested, you can go to Angeline Lillard�s CV page on the web and download her paper �Ethnopsychologies� It seems FP is really not stagnant at all!