A simple-minded functionalist theory of pain
Pain is a mental state. Let's suppose we are trying to produce a functionalist theory of it. We begin by gathering together all the truths we normally suppose a mental state must satisfy if it is to be a pain.
The American philosopher Ned Block has suggested how we might do it, for what he calls the “ridiculously simple theory,” which we'll call “T”, thatT: “Pain is caused by pinpricks and causes worry and the emission of loud noises, and worry, in turn, causes brow wrinkling.”
T is ridiculously simple. But we can still use it to elucidate some general points about functionalist theories of the mind. For with this simple theory we can see how the charge of circularity might be avoided.
So, begin with T. We write it as one sentence. Then, we replace every reference in the sentence to pain—whether actual or potential—by a letter, and each other, distinct, mental term by a different letter, to get
T': X is caused by pinpricks and causes Y and the emission of loud noises, and Y, in turn, causes brow wrinkling.
(In this case, since there is only one other mental term, “worry,” we only need the one extra letter, Y; but in other cases, as we'll see, we would need many more.) The next step is to write in front of this the words “There exists an X, and there exists a Y, and there exists a... which are such that” for as many letters as we introduced when we removed the mental terms. So, in this simple case, we get
R: There exists an X, and there exists a Y, which are such that X is caused by pinpricks and causes Y and the emission of loud noises, and Y, in turn, causes brow wrinkling.
Notice that we now have a sentence, R, that has no mental terms in it.
It allows us to say how pain works without relying circularly on knowing what “worry” is. It would be circular to rely on our understanding of what “worry” is, because, in a full functionalist theory, we would be going on to define worry later. Now, finally, we can define what it is for someone to be in pain. For we can say that someone—let's call her Mary—is in pain if there exist states of Mary's, X, and Y, which are such that X is caused by pinpricks and causes Y and the emission of loud noises, and Y, in turn, causes brow wrinkling, and Mary has X. If Mary has such a state, a state that functions in this way, she is in pain.Now, T is, as I said, ridiculously simple. But it has allowed us to see how to define one mental state—pain—that can only be explained in terms of its interactions with another mental state— worry—without assuming that we can define the other mental state first.
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