Lewis and Radical Interpretation

Briefly: Lewis wants to know what, given P (where P is the totality of facts about Karl, his subject, as a physical system), would enable us to solve for the rest of Karl's psychological makeup: his beliefs, desires, the meaning of his statements, and anything else that could be said following these things.


Put another way, Lewis wants to know how beliefs, desires and meanings are normally related to one another, and to sensory input and behavioral output. He believes it is possible to construct a theory that adequately accounts for all of these, given P.


"It must amount to nothing more than a mass of platitudes of common sense," he says of the theory. Why must this be the case? Because Lewis is convinced that the fundamental principles of our common-sense theory of persons (that's a mouthful) already implicitly define belief, desire and meaning.
Perhaps it is just a case of weeding these implicit definitions out and making them explicit?


He does believe that this is the case. Nonetheless, the first formulation of the method he has in this paper, even by his own admission, places too much emphasis on language as a vehicle for belief, and not enough on language as a social practice or behavior as a manifestation of belief.  I agree heartily on this latter account. He goes on and gives two more methods of discovery that depend less on these sorts of things, the second of which I believe to be most like the way we naturally go about trying to determine belief.


Agustín Rayo has asked us: "Lewis thinks there is a tight connection between folk psychology and rationality, and accuses his critics of not paying enough attention to this connection. Is he right?"


Perhaps he is partly right. Perhaps the kind of theory he wants is one that science would not necessarily give us, but that would be a systematization of the way we ordinarily go about ascribing belief. Nonetheless, I'm not quite sure why he needs such a systematization in the first place. Is it that the concepts of belief, desire and meaning are so important that, even if science were to break them up into component parts that did not remotely resemble the conception of them in the human mind, we ought to stubbornly find a way to keep using them? What justification is there for this view of his?
And a further question: why challenge people to systematize a method we all use for purely socially beneficial purposes? Why does there have to be a science to belief ascription?






Sept. 18th enmendation:
Lewis' paper (or section) called "Reduction of Mind" is quite brilliant in its discussion of the failures of contemporary philosophy to address narrow content. I also like most of what he has to say about beliefs. If any of you are interested, it is worth a read.