Knowledge expressed using “I” is different from knowledge expressed using other modes of reference (names, descriptions, demonstratives). I know that I wrote The Subjective View and I also know that Colin McGinn wrote The Subjective View, but these are different pieces of knowledge despite the identity of reference. This is made vivid in amnesia cases: I might forget that I wrote that book while coming to learn that someone called “Colin McGinn” wrote it—I don’t know I am the author though I know who the author is (that McGinn fellow). I also might know that I did something and not know that Colin McGinn did, because I have forgotten who I am and what my name is. Thus “I am Colin McGinn” is an informative statement. But how exactly do the two pieces of knowledge differ—what makes them different? What is distinctive about first-person knowledge? Evidently I can acquire knowledge of myself expressible using “I”, but what is the specific nature of such knowledge—what makes it stand out from other sorts of knowledge of objects?
One possible response is that it is not unique but merely a special case of an informative identity statement. It is similarly true that “Hesperus is a planet” and “Phosphorus is a planet” express different propositions, but there is nothing special about either proposition. There are simply two modes of presentation associated with the two names, so knowledge of one doesn’t imply knowledge of the other. Likewise, it may be said, “I” in my mouth expresses a different mode of presentation from “Colin McGinn”: that is what the difference consists in. But this response misses an important point, namely that I could also not know a proposition that refers to me by a different name (or description or demonstrative). But that difference is not the same difference as the difference between my name and “I”: the former could just consist in a different description being true of me, while the latter does not. The proposal blithely employs the notion of a mode of presentation without saying what it consists in for my use of “I”, but that is empty unless something is said to explain what this mode of presentation might be. In reply to this objection it may be offered that the difference is that “I” is an indexical while proper names are not: that is how the two propositions differ (now pick your favorite theory of indexicals). But again this conflates cases, since “you” and “he” are also indexical but don’t track what is special about first-person knowledge. I might also think that he wrote The Subjective View while seeing myself in a mirror without realizing it, but this again doesn’t give me the knowledge that I wrote that book. It is something about first-person knowledge in particular that is special not indexical knowledge in general or merely the possibility of more than one name for the same object. We can’t assimilate the case to a wider phenomenon; we need to identify what it is specifically about first-person knowledge that makes it different from other sorts of knowledge of objects. When I know a fact about myself that I express using “I” how does this differ from knowing the same fact about myself without using “I”?
I think that to answer this question we need to dig deep, metaphysically and epistemologically; it is not a merely linguistic phenomenon that we are concerned to understand. The answer I want to propose is not easy to grasp and I may have trouble explaining it. The basic thought is that we may not have the sort of knowledge of ourselves that we think we have—there is something peculiarly problematic about such knowledge. I don’t really know that I wrote The Subjective View, even though I know quite well that Colin McGinn wrote it. This is because there is a gap between my knowledge of myself qua myself and my knowledge of the person known as Colin McGinn. I can coherently say to myself, “I know that CMG did such and such, but I’m not sure that I ever did such and such, because I’m not sure that the person so named is really me”. I think he is, but the question admits of rational doubt. Put differently, I am not certain that I am a particular person in the objective world—that this self is that person. I am in a sense alienated from that individual, as if he is more my avatar than I myself. So I am unclear that his exploits are really mine. Let me try to elucidate this doubt by constructing a fanciful thought experiment.
Suppose that I actually exist in an immobile form in a safe room of some sort (a brain in a vat, to make it concrete). However, I have a body assigned to me that leaves the room and wanders around the world acquiring a history—that is, the experiences generated by this body are reproduced in my mind, so that it is as if I am wandering about. I thus acquire information about the doings of this body. We might be inclined to say that I leave the room with my body (though my brain stays put) and come to have various properties as a consequence. This already sounds strained and a further wrinkle can put it under pressure: suppose that another person commandeers my body and goes out into the world using it as he desires. This individual is called “Colin McGinn” and he does many things, including write books. He is not I. Nevertheless, I might acquire various beliefs about myself as a result of what this individual does, e.g. that I wrote a certain book. These beliefs would be false in the situation described: I never do anything—he does all the doing. It merely seems to me that I do these things.
The skeptic now steps in to urge that this might be true of my actual situation. How do I know that what the person called “CMG” does is really done by me? Maybe I am not embodied at all and the wandering person I think of as myself is not me. Maybe I went through the mental motions of writing a book but none of this caused a book to be written; instead someone else in a certain body did the actual physical writing. I have all sorts of impressions as of that body, as well as knowledge of my subjective states, but when I think I have acted in certain objective ways I really haven’t. After all, it doesn’t follow from the fact that I performed a certain series of mental actions (choosing words, etc.) and that a certain body moved in ways corresponding to this series that I performed those physical actions. I might be ensconced impotently somewhere while all the action is going on elsewhere, mistakenly taking credit for it. I might have no active presence in the world at all, though someone that does matches me in certain ways. I think I have a history of objective happenings, but perhaps I don’t, having only a mental history and an uneventful history of physical immobility. For instance, I never went to school in Blackpool, even though it seems to me that I did—it was someone else who went there in my stead. Accordingly, my beliefs about myself are generally false: my self-knowledge is not what I thought. This is because of the gap between how I appear to myself from the inside and what I objectively do or am subject to. I could express this gap by saying, “I might not be Colin McGinn”. The person with that name might well exist and have the history I take myself to have, but I am not identical to that person. I can therefore sensibly say to myself that I might not be Colin McGinn, i.e. the person who has such and such a history. I know various facts about him and I have no qualms about attributing those facts to him, but there is a question as to whether he is I, i.e. the individual I encounter from a first-person perspective. The objective self that is called “CMG” might not be the subjective self I refer to with “I”. That objective self, so conceived, certainly did various things, but he might not be me, so it is doubtful that I did those things. My putative identity with CMG is thus questionable because of the gap that exists between the subjective self and the objective self, i.e. between the self I encounter within and the public self that exists objectively. The very thought that I have an objective identity can seem like a rash conjecture, even when I don’t doubt that there are objective persons. How can I be something in the world? The world exists with persons in it, but the thing I refer to with “I” might not be one of these persons.
Let me try to put the point more intuitively. When I think of myself (de re) as Colin McGinn I have no trouble with the idea that this individual has a certain objective history—that very individual. I am thinking of an entity that has an objective existence, is observable by others, with a body, etc. But when I think of myself as myself using “I” I feel a gap open up between this entity and the objective facts I associate with it, which I might express by saying, “It is problematic that this entity ever did any of those things”. From the first-person perspective it is moot whether the self even has such attributes; they seem external to it, not part of its intrinsic character, not part of what is given with the self. Thus we feel that the self stands apart from the attributes commonly attributed to it when conceived from the third-person perspective. This is the difference between “I” and “CMG”: the latter presents no gap between the object and the facts that hold of it, while the former does present just such a gap. That is why it can seem surprising that I am an objective being at all: for how can I be that? I seem to myself from the first-person perspective to be of the wrong category to be an objective person, so I am uneasy about claims to self-knowledge of the usual kind–for example, that I wrote a certain book. I feel myself to be curiously remote from the facts of my supposed objective history, and would not be confounded by the discovery that I am not the real subject of these facts, as in the skeptical possibility described earlier. The fundamental form of this kind of thought is that Iam not my body, so that anything it does is not an attribute of me—though I have no qualms about attributing these things to the person I call by my name. This is no doubt what Descartes (and many others) was driving at—the self is not to be identified with the body, so that the history of one is not the history of the other. We could put this by saying that the inner self is not the objective person; of if he is, that is a problematic proposition.
Metaphysically, we could say (riskily) that the self is a bare particular with respect to objective facts: it is not qualified by such facts or presented as instantiating the properties in question. But when we think of a person from a third-person perspective he or she is not similarly conceived as a bare particular: here the facts are integral and salient. It would accordingly be bizarre to offer a theory of the semantics of “I” that defines it by reference to objective circumstances, as that “I” in my mouth means “the author of The Subjective View”, though that theory is by no means absurd as a theory of the name “Colin McGinn”. Put in these (risky) terms, self-knowledge is knowledge of a bare particular (relative to objective facts) that has certain extrinsic attributes by virtue of a relation to something else, while knowledge of the third-person kind is knowledge of an object endowed with various intrinsic properties. Of course, we must add that the self is not a bare particular tout court, since it has an array of mental properties that can be introspected—but we have been speaking of knowledge of physical properties of the person. With respect to mental properties, there is a strong contrast with the kind of self-knowledge discussed so far, since in their case we can’t envisage the possibility of someone else being the subject of these properties. I can’t say, “Someone else may be the person suffering these pains” as I can say, “Someone else might be the author of The Subjective View”. In the self-ascription of mental states I am not venturing beyond the subjective self, as I am when attributing physical attributes to myself. In a sense, then, the former case is like the case of the objective self in that both don’t involve any attempt to cross a metaphysical divide; it is only self-knowledge of objective facts that involves this kind of leap—the kind of knowledge expressed by “I am the author of The Subjective View”. That is the peculiar case, mixing as it does the subjective with the objective, thus inviting the protest, “But how could I have such attributes?” What I most intimately am is divorced from such worldly matters, or so it seems to me from the inside. That may be a false view to take, but it infects our attitudes towards self-knowledge nonetheless: it is what makes “I am CMG” such a potent and troubling thought—the very idea that this might be that. Surely there comes a time in everyone’s life when they recognize that they are a person existing in an objective world, as well as the subjective self with which they have become so familiar; and this is a potentially vertiginous thought—a kind of expansion and contraction at the same time (“I am more than this locus of subjectivity, but also only one object among many”). I am suggesting that such fraught thoughts are built into self-knowledge and give it the peculiar character that it has. There is nothing particularly strange about knowing objective facts about a named individual, or about someone knowing in the first-person that he or she has certain mental states, but it is strange to know that you yourself have certain objective attributes—because that is to combine the inner and the outer in a problematic way (as the skeptic points out). At its most basic, the remarkable (and terrifying) thought is that I am someone.