Radical interpretation

Imagine that we have undertaken the task of coming to know Karl as a person. We would like to know what he believes, what he desires, what he means, and anything else about him that can be explained in terms of these things. We seek a two-fold interpretation: of Karl 's language, and of Karl himself. And we want to know his beliefs and desires in two different ways. We want to know their content as Karl could express it in his own language, and also as we could express it in our language. (For instance, we want to know whether 'ownsnay isyay itewhay', is a sentence that Karl could use to express something or other that he believes; and also whether Karl believes that, as we would put it, snow is white. Of course, Karl ' s language just might turn out to be the same as ours that is part o f what we want to find o u t b u t the two questions are independent even so.) Imagine also that we must start f rom scratch. At the outset we know nothing about Karl 's beliefs, desires, and meanings. Whatever we may know about persons in general, our knowledge of Karl in particular is limited to our knowledge of him as a physical system. But at least we have plenty of that knowledge in fact, we have all that we could possibly use. Now, how can we get f rom that knowledge to the knowledge we want? I can diagram the problem of radical interpretation as follows. Given P, the facts about Karl as a physical system, solve for the rest. P, our ultimate data base, gives us the whole truth about Karl as a physical system. I t tells us how Karl moves, what forces he exerts on his surroundings, what light or sound or chemical substances he absorbs or emits. It tells us the same things about all of Karl ' s material parts, great or small, permanent or temporary. I t tells us all the masses and charges of the particles that compose him, and all the magnitudes and directions of the fields and potentials and radiation that pervade him. I t tells us not only his present physical state but also his physical history; and not only the actual particular physical facts but also the nomic or counterfactual or causal dependences among them. I t tells us higher order facts, if need be: