Monday, September 28, 2009

Etiology and Meaning

Two people have the same (true) belief. However, one person has the belief because of personal experience. The other person has the belief because a clever lawyer has talked him into it, using deceptive arguments. In what way are their respective beliefs different? The propositional content is the same, and the proposition is true. And yet one has the intuition that the two "beliefs" are not the same kind of mental state. As Plato sees it in the Theatetus (200e-201e), one of them has knowledge and the other does not. One can have a belief by accident, or for the wrong reasons. Thus there is a difference between an accidentally true belief and a belief that is true for the right kind of reasons. One might compare such a belief, as Hilary Putnam does in his article "Brain in a Vat," to an ant trail, say, that bore a resemblance to a face. That would not really be a representation of a face, and nor would one really know anything about the world when possessed of a representation of the world that was only accidentally true.

To see the metaphysical point, imagine that a skywriter perfected the art of cloud-portriature: for a price he can render a likeness of anyone you choose in the medium of clouds, let's say Elvis. Suppose another cloud, unmanipulated by any skywriter, happened to form next to the cloud-portrait. The two clouds might be molecule-for-molecule identical, and both might have the same uncanny similarity to Elvis, but the cloud-portrait seems to differ from the natural cloud in having the property of meaning, or representing, Elvis. Here's a final example that makes just the same point: one day you notice that you have two copies of the city phone book. Thinking nothing of it, you keep one upstairs and one downstairs. You've used them both any number of times, for example to call out for your favorite pizza. However, unbeknownst to you, one of these objects is not a phone book at all. Through a near-miraculous event of quantum randomness (just making that up!), a doppleganger "phone book"-object has appeared in your house. It is both physically and functionally identical to the actual city phone book. Except for one thing: it contains no names, addresses, or phone numbers. It contains accidental conglomerations of matter that resemble such symbols, but it does not contain any actual symbols.

There is a conclusion wrapped in a moral wrapped in this point. The moral is that the significance (the intentional/semantic content) of a symbol is not just a function of the physical properties of the concrete symbol (the physical token), nor is it (more surprisingly) picked out by the functional role that the symbol supposedly plays in some larger process. The significance of a symbol (a name, say) depends on the etiology of the symbol, the process through which that symbol came to function as it does. "Meaning" is a complex relational property, a description, really, of relations between some person or persons and the world. Putnam's slogan for this moral is "Meaning just ain't in the head."

Notice the close affinity between Putnam's externalism and Saul Kripke's account of proper names as "rigid designators." (The affinity is not coincidental, as both philosophers are inspired by Wittgenstein.) Kripke claims that a symbol is an actual name of a thing or a substance just in case that symbol was originally used to designate the thing or substance in question. The payoff of this simple account is that the "meaning" of the name turns out to be nothing more than the history of that symbol in human behavior. There is no mysterious property of meaning left over.

The conclusion from this moral is about intentional predicates (predicating "propositional attitudes" of persons). When we say that {Sam believes that "The fish are in the bucket"}, externalist approaches hold not only the relatively clear point that intentional states are not any sort of brain- or body-state "in the head" (they are predicates of whole embodied persons), but that they are not "mental" states at all, they are "states of affairs": historical and behavioral relations between the person and his/her environment. Seen this way they need not advert to any "mental content": externalism is eliminativist as to mental representation, at least insofar as intentional descriptions are read as adverting to mental representations. The semantics of words like "belief," "desire," "hope," "fear" and so forth are handled without reference to internal "states." There are all sorts of causes inside the body of the person, of course, but these can all be described functionally within the context of the overall intentional description (and only within that context). To say that my intentional state is about something outside of my body is to say that I am in a certain relation to something outside of my body. (Nor is there any reason to think that this account fails for imaginary things like Santa Claus: I am not imagining that Santa Claus is in my head, I'm imagining that he's in my chimney.)