Anyone who has read enough philosophy of mind knows that when analytic philosophers talk about pain, they talk about C-fiber stimulation. Indeed, it is commonly discussed whether pain and C-fiber stimulation are identical. A problem with this example is that it is not a very good one. The reason is found in a common experience, double sensation of pain.
You've no doubt had the experience at some point of a very intense, swift sharp pain, precisely localized, followed by a slow, burning pain, which is more vaguely located. The experience of these is very different. They also have different physiological bases. The first pain, the swift, sharp, precisely localized one, involve the stimulation of what are known as A-delta fibers. A-delta fibers conduct impulses very quickly. The second pain is the C-fiber pain; C fibers conduct impulses much more slowly. This is why we experience it as one pain following after another; indeed, the second pain can be several seconds slower than the first. Thus even when we are dealing with what is usually called nociceptive pain (pain that signals a specific potentially damaging event), we have clear experience (and confirmation in terms of underlying causal account) of two different kinds of pains. And nociceptive pain is not the only kind of pain; you can have pains that do not signal specific potentially damaging events, and have a different neural account entirely. There is an entire genus of things that we call pain; physiologically we need more than one account to handle them.
(This is not even considering, of course, the fact that no one actually studying pain regards the firing of these fibers as the whole story of pain.)
Now, if you point this out to analytic philosophers of mind, you will often get a response something like this. "Perhaps, but this does not affect the argument; just take 'C-fiber stimulation' for whatever account -- or in this case whatever disjunction of accounts -- is the real one." And some respect has to be given this. It's much as when we are reading Descartes on animal spirits; it is very amateurish and shows a lack of critical thinking skills to assume that we can simply dismiss what Descartes says because we have an electrochemical account of the nervous system rather than Descartes's hydraulic one. This is because some things that Descartes says may carry over fairly easy from one type of account to the other, without seriously affecting the argument being made. And I think it definitely is true that for the purpose of this or that point it is often the case that it doesn't matter whether philosophers of mind talk about C fibers or A-delta fibers, or, for that matter, animal spirits. Nonetheless I'm not convinced that this detachment is always entirely benign. For one thing, for this to work as a response, it has to be the case that nothing about C-fiber stimulation, specifically, is actually essential to the argument; the phrase is just being used to stand in for what, if we were more aboveboard, we would call 'whatever physical system has the properties to do what we are talking about'. This means that we are only talking at a very abstract level, one that already posits something simply by the way we are stating it. Now, this positing may be quite benign, but it needs to be shown rather than assumed.
Moreover, I think it's important to point out that at this point we are using a very specific empirical/scientific-sounding term as nothing more than a marker for a much more abstract and vague idea, and this raises the worry that it will create the illusion of a more substantive and adequate argument than is actually there. At the same time, we're using a single marker to indicate what requires, by our best information, a far less simple account, on both the physiological and the experiential side. We have to ask ourselves, again, whether this ever creates the illusion of an account or argument being stronger than it actually is. I don't know if these worries are fulfilled; but I think it's worth asking the questions. In the Cartesian case we can, if necessary, establish the modifiability of the original account, with specific experimental evidence and physiological accounts. Can we always in reality do this in, say, arguments for and against mind-body identity? It's a question I've not seen people answer.
