For Descartes, Locke, Berkeley, and Hume, there could be no problem when it came to the awareness of pain. They all took it for granted that of necessity a mind is always, at the time, infallibly informed regarding whatever “ideas” come its way — or whatever “perceptions,” in Hume's phraseology. As Hume put it: “Since all actions and sensations of the mind are known to us by consciousness, they must necessarily appear in every particular what they are, and be what they appear” (Hume, Reference Hume, Selby-Bigge and Niddich1978, p. 190).Footnote ¹ (The use of “since” here seems to imply an argument or explanation; but what that might be is hard to guess.) When what was in question was the mind's current sensations, there was simply no place in these four thinkers’ philosophies for the occurrence of any sensations in the mind that were not fully conscious.

Philosophical followers of Wittgenstein and Sartre aside,Footnote ² people today speak freely of “subliminal perceptions,” and, as far as dispositional states go, at any rate, we mostly have no difficulty with the conception of mental life that is not conscious. Surely our grandmothers — and perhaps, too, the grandmothers of the philosophers named — were in no doubt that it is only too possible, for instance, to fall in love without realizing it, or to fall out of love without realizing it.

Is pain a counter-example? Is it an example of how, in a certain sort of case, the existence of true belief and the existence of the fact believed are not really two different existences, of which each could occur without the other? It is not hard, perhaps, to admit the Cogito fact as such an example: our thought of that occurrence long ago is certainly something different from it, and yet Descartes’ thought of it right at the time was not. But could “subliminal pain” be something conceptually impossible?

In 1948, C. D. Hawkes and Nicholas Gotten reported to the American Neurological Association on 10 dying patients treated for intractable pain by pre-frontal lobotomy operations:

Anaesthesiologist Henry K. Beecher reported on U.S. soldiers wounded at the World War II Battle of Anzio in Italy:

“These men,” Beecher notes, “were clear mentally, and not in shock; they had not had narcotics recently and none at all in many cases” (Beecher, Reference Beecher1959, p. 164). But patients like that, he says, “complain as vigorously as normal men at an inept venipuncture; so there is no total pain block” (Beecher, Reference Beecher1959, p. 166).

Psychologist Ronald Melzack and neurologist K. L. Casey comment that this

The lobotomized patients said that they did notice their pain when they thought about it, but even then they were indifferent to it. The “specificity theorists” of pain neurology said that the wounded soldiers were all in pain, but that not all of them realized that. Melzack and Casey, though, will not hear of such things. After all, it is not necessarily amiss for scientists sometimes, on conceptual grounds, to overrule — or to “reinterpret” — what people spontaneously say. Ordinary language can be inconsistent; it can be confused. And Melzack and Casey do have a point about the absurdity of “nonpainful pain.” It would not be difficult to rule the possibility of “subliminal pain” out by a linguistic stipulation to the effect that nothing of which the mind is not at the time aware can count as “pain.”Footnote ³ And what we can stipulatively accomplish by design, natural language can accomplish — or can have already accomplished — through its processes.Footnote ⁴

Even when consistent and unconfused, the semantics of ordinary-language expressions can be “multi-stranded” and rather lacking in boundary-precision. The question here is not what the exact meaning of the English word “pain” is, but whether it is ever possible for the word to stand for something whose presence and whose absence alike are infallibly known by the mind affected. For the “naive” concept of a “set,” it turns out “there is no room in logical space,” for example — a fact known since the work of Bertrand Russell over a century ago.Footnote ⁵ Could a parallel surprise be in store for us when it comes to pain?

Certainly, the easiest way to ensure the logical infallibility of a belief that one is not in pain would be by way of stipulating that to be in “pain” is to be in some state S and know that. But couldn't one fail to also know that — the fact that one was in state S and knew that? Or know that fact, but fail to know that one knows it? The mind's awareness of something need not guarantee any awareness of that awareness, it would seem, and, if no “pain” experience has occurred without an awareness of it, then that of which the awareness is an awareness is not a “pain” experience without an awareness also of that awareness. And so on. Nothing in a finite being's mental life can be of more than finite complexity; and so, are we not presented here with an impossible infinite regress?

However, if the term “awareness” means something dispositional, or else means whatever non-dispositional reality it is in the mind that gives rise to the disposition(s) in question, then this is not going to be a problem. For a single “base” reality can give rise to any number of distinct dispositional facts — facts about what would happen if certain things were to take place. It is unproblematically the case that, as you read these words, you are aware that you are reading them, and aware as well of that awareness, and also aware of that awareness — and so on. And so, nothing stands in the way of language itself ruling out the possibility of any “pain” which the mind is unaware of.Footnote ⁶

That, then, would give us half of logical infallibility. It can be impossible to be in pain without being aware of it. But can it be impossible also to believe that you are in pain without actually being in any pain? Conceivably some of Beecher's pain-denying wounded could be persuaded by medical experts that their neurological state was such that they “really were in pain” in spite of appearances to the contrary; and conceivably those experts could be simply lying about the patients’ neurological states. But even if this were not just a case of employing “scientific” flim-flam so as to get lay people to accept a misuse of language, it would not be a significant counter-example in the present context. Surely the prime candidate here for logical infallibility is immediate, that is, unreasoned, belief that one is currently in pain.

An easy way of stipulatively ruling out any possibility of having an immediate sense of being in pain without in fact experiencing any, would be to define being in “pain” as being in some state S or having an immediate impression of being in state S or having an immediate impression of having an immediate impression of being in state S or … — but that would sacrifice the logical infallibility of an unreasoned belief that one isn't in pain.

Eric Schwitzgebel writes:

By contrast, the claim here will be that the use of a word like “pain” in natural language is sufficiently indeterminate, covering as it does a spread of related senses, that in some of those senses it is logically impossible to be in error “immediately” as to whether you are in pain, because the thought that you are in pain and the pain are really the same thing. The problem taken up is the problem of how it is possible for a thought (other than a thought like Descartes’ Cogito thought) to have for its whole subject-matter: itself. (Without any Liar Paradox resulting.Footnote ⁷)

What is pain? It is an immediately aversive sensation “referred” to a spot in the subject's body (including, of course, as we know, body parts now missing: “phantom limbs”). The pain sensation has in each case its own phenomenological character — “crushing,” “burning,” “tearing,” etc. — in addition to features such as intensity, spread, and intermittance. But, as Melzack and Casey say, in effect, without aversiveness it is not what we call “pain.” There must be in the mind a desire (or a suppressed tendency to desire) that conditions be different from what they are at the spot in the body where the pain is felt. And with that aversiveness, the sensation is painful, whatever else it is phenomenologically.

Is not a “desire” for any result a (defeasible, that is, outweighable) disposition — or whatever mental reality gives rise to such a disposition — to try, should it be possible and necessary, to bring that result about? In other words, something mental which expresses itself, should such be known to be possible and necessary, in means-taking action. However, a belief that one desires something, no matter how ill founded, can readily give rise likewise to means-taking action aimed at securing it (overridably, of course, should a contrary-tending desire be strong enough). Hence, such a belief can be a “desire,” in the standard sense of the word. And so, to have an “immediate” sense that you are in pain somewhere can amount to being in pain there. This can be the other half of the sought-for logical infallibility semantics (the pain/apparent-pain equivalence). Though a belief can sometimes be a desire, it is still true that to believe something to be so is not to desire it to be so. In the present case, it is to desire something else: what is here believed is that a desire exists; what is desired is not that supposed desire, but rather its object, relief from an aversive sensation (thus rendering the belief correct).

But how could having an (unreasoned) opinion that one was in some desire-state ever amount to being in that state? Don't folk psychology and philosophical theory tell us alike that our desires and our beliefs comprise, as it were, two blades of the “scissors-action” which produces purposive behaviour — one “blade” giving us our goals, the other giving us our estimate of pertinent opportunities and obstacles? According to this model, all voluntary behaviour is the result, jointly, of such an ensemble of motivations (of various different strengths) and an ensemble of beliefs (held with various degrees of confidence) — with distinct psychological roles being played by the desires, on the one hand, and the beliefs, on the other hand. Metaphor aside, though, why couldn't the same mental state ever play (part of) both roles?

In the absence of any argument to the contrary, it appears that it need not be only with the Cogito that we can see an example of believing the occurrence of which logically ensures the belief's truth because the existence of the believing and the existence of the fact believed are really not two different existences.