Personal identity is one of my favorite philosophical subjects to think about. It's been a mystery to me literally as long as I can remember. I remember being a kid and creeping myself out by wondering things like, "How do I exist?" and "Why am I me rather than someone else?" "If you replaced all my memories with other memories, would anything of me remain?"
Philosopher Julian Baggini recently gave a talk on this subject at Tedx.
I mostly agree with what he says, but I have my quibbles and additions.
Things and their properties
Baggini claims that objects are mere aggregates of properties, and so it makes little sense to look for the essence of water beyond its formula H2O or the essence of a watch beyond its parts. Likewise we should not look for a self beyond the parts of which it is composed: memories, beliefs, patterns of behavior, etc.
It doesn't seem that objects uncontroversially are their properties, though. If that were the case, then—keeping the example of the watch—I might not be able to tell the difference between the watch which is on Mr. Baggini's wrist and Mr. Baggini himself. The watch face, watch hands, gears, wrist band, skin, forearm hair, veins, and bones are all in very close proximity with one another, yet we know some of those properties form an arm and others form a watch. Yes, we could remove the watch and find out it's separate, but we could do the same thing with the skin and veins and make the same claim.
If we're dissatisfied with that account of things—which we should be, since it doesn't seem specific enough—we might switch to a more scientific, less subjective account. Then we go beyond the issue of objects and their properties and get into the realm of experimental science. There it turns out that things like watches and forearms are not in fact real "things" at all. The particles and forces composing them are. Then we might say that where the Indian Ocean ends and the Atlantic Ocean begins is a matter of convention, but the properties of H2O are not.
But in fact the same problem we had with objects and their properties pops up here, too. There's a debate in the philosophy of science about whether laws of nature really exist, or whether they're just observed regularities. Our senses or our instruments tell us hydrogen and oxygen behave this way under these circumstances, but it's not as though we perceive the necessity or universality in that. And yet, we do believe mathematical formulations like E=mc2 are more than mere conventions. They seem to constitute real insight into nature itself. And our basic curiosity as human beings leads us to believe there are other such laws "out there", waiting for us to find them.
Selves and their Mental States
The same line of reasoning I've used here for physical things can also be applied to the mind and the notion of the self. If I reflect upon my experience, I'll observe sensations, memories, beliefs, cognitions, judgments, emotions, and the like, but I will never observe anything in addition to those things that I might, with right, apply the term "self". The philosopher David Hume famously pointed this out in the 18th century, but it's really an old idea, and Baggini rightly attributes it to the Buddha.
But the story doesn't end there, just as it didn't in the case of physical objects. While it's true that I have no sensation of a self apart from the aggregates mentioned above, there is a sense in which I am given to myself that has nothing to do with these other things. Namely, I am aware of myself as this awareness.
If I recollect something embarrassing or shameful from my past, I might think, as Baggini suggests, "That's not me!" or "I'm not like that any more!" But of course that is you, and that's why you feel ashamed! Just because something happened in the past, and just because I was acting upon beliefs I no longer hold, there is still something that appears constant, and that's the mental "stage" that the events took place on. Regardless of whatever else changed, those things happened to me, not to anyone else.
But when we say "to me", we don't always mean they happened to my body. We often mean something like that they existed for me, and that's the dimension of experience Baggini does not adequately flesh out. When I perceive a ripe, red apple, there are three things: the act of perceiving, the apple itself, and the knowledge, however implicit, that I'm undergoing that experience. This is what the French philosopher Jean Paul Sartre called "non-thetic awareness". It doesn't require a special act of reflection (which Sartre called "thetic awareness"). If it did, then self-awareness would require an infinite regress of awareness of awareness of awareness... Instead, it's an immediate intuition we have, before we apply concepts to our own experience, that, indeed, this isn't just happening, it's happening for me.
So there's a parallel problem here to the one we had with physical things. It's not enough to describe self-experience just in terms of its properties (the sorts of things that pop up as objects of experience), because there's still a subjective component that has to be taken into account. This is important because, no matter how I decide to describe myself—whether by my beliefs, my memories, my actions, or whatever—I'm going to include in that account that I am also a subject, i.e., the experiences happen for me.
The Intentionality Thesis
The real spooky stuff starts when we try to get to the bottom of what it means for something to be for me. The overwhelming temptation is to attempt to understand subjectivity as just another thing in the world, i.e., as an object. And indeed, we do something like this when we reflect upon (using thetic self-awareness) upon our own experience. But if something is an object for us, it can't be us, and so when we deliberately reflect upon such states, we find that we're "too late", so to speak, and what we were trying to grasp has been converted into its opposite. In order to understand subjectivity, we have to understand it as subject and not as object. And that's very hard.
One solution to this problem is to argue, as both Heidegger and Sartre did, that awareness—they called it "intentionality"—always only has as its content some external thing that is not intentionality. So when I perceive that juicy red apple, I am perceiving the apple itself, not some property of perception. This flies in the face of some of our intuitions about experience, according to which our minds only represent the world, and we're always only deal with our mental states about the world, not the world itself. The argument in favor of the intentionality thesis is that there's no experiential evidence for the representationalist view. I see evidence of the apple and nothing else. I don't even know what a representation would look like, so why should I believe I "have" it?
Well what about illusory objects, beliefs, and mental pictures? Aren't they just contents of the mind? According to the intentionality thesis, our perceptions can be wrong, and not everything we perceive or experience belongs to the physical world. But you have to be careful what theoretical components you bring in to explain this. First, if I have some hallucination, this is proved by comparing my experience with the experience of others, sometimes but not always by means of experiment. At no point do I ever get to immediately compare my experience of something to reality in and of itself. Second, even in those cases where I'm aware of something that has only subjective reality, like a belief, I am only aware, again, of three things: the belief, the act of believing, and the implicit awareness that I am the one believing this. Nothing whatsoever about that experience entails that there is another entity, "the mind", and that the belief and the believing are taking place "inside" that entity. There's just the object, the act that "reaches out" for the object and which can be distinguished from it, and the bare, minimal sense that this is an experience for me.
Now, if you have a good argument against the intentionality thesis—which you might, since it's controversial—then you'll wiggle by the next move. But if you can't, fasten your seatbelts.
If there's always only these three components—intentional act, intentional object, and non-thetic self-awareness—then there is no "mind space". The mind is just a theoretical construct. All there is is just intentionality. But this means that, whoever "we" are, we're not our minds, at least not in the sense of being a container of experiences, because there is no such thing.
You might think, "Yes, but there is the intentionality itself, and the intentionality is aware of itself. I am the intentionality."
Good. But what is intentionality? Nothing. I mean that in a technical sense: it is not a thing. It can't be. To be a thing means to be an object for intentionality. If I can see it (or perceive it or think it or desire it or...), then it cannot be me. And when intentionality is aware of itself, as in non-thetic self-awareness, it has itself as bare intentionality, not as anything else. Intentionality—really awareness in general—is therefore "empty". There can be no separate self to find "inside" of it, because there is no "inside" to intentionality. Awareness exhausts itself completely in the act of being aware of the object. The only "beingness" to be found is on the other side of intentionality, on the side of the object.
Sartre wrote a book about this. It should be plainly obvious from what I just said why he called it Being and Nothingness. It's a long book, because he felt a lot of interesting things followed from this.
But you don't need to embrace existential phenomenology. The almost identical realization was made 2,500 years ago by the figure we call the Buddha. Some of the details are different, but the main difference is that the Buddha advocating using meditation and not just reason to discover the truth of anatta or "no-self". If you follow the meditation instructions given by the Buddha, you should be able to perceive no-self as well as the characteristics of impermanence and suffering. And then you will be free of the cycle of samsara or suffering and achieve happiness.
Transcendental vs. Empirical
Now, you might think that was a very verbose way to say what Baggini managed to get across in a lot fewer words. Not quite. There's a subtle but important difference in what I'm saying. The sense of no-self that Buddha, Heidegger, and Sartre discovered and talked about is different from the sense of no-self that Hume and Baggini point to. The latter is an empirical sense of no-self. It's saying that there's no way to cobble together a separate, permanent sense of self out of things like memories, beliefs, thought patterns, actions, personality, and the like, because (a) these things themselves are always changing, and (b) upon reflection there is nothing else I could possibly base a sense of self on.
True! But this line of thinking leaves untouched a transcendental sense of a self. According to this view, you can keep my memories, thoughts, personality, and everything else, because it's my consciousness that's truly me. And while there may be no good external, empirical evidence for the existence of this consciousness, I still know it inwardly. And this inward grasp I have of myself as a separate, transcendental being is inviolate, since it depends upon no particular conscious awareness. I might "lose my mind", but only in a manner of speaking! If I have crazy thoughts, there's no doubt those thoughts are mine, because they take place inside my mind.
That's the notion of self that Buddha demolishes. Rather, that's the notion of self Buddha claims is illusory, and its illusory nature can be clearly perceived if one carries out a careful, systematic investigation of experience itself. And unlike a philosophical argument, which may leave an illusion intact in practice even while destroying it in theory, following the Buddha's procedure is supposed to permanently remove the illusion and grant one an unobstructed, permanent view of reality.
So I really wanted to make that distinction, because I think too quickly people want to say, "Oh right, of course, there's no permanent self. We all know that." But the claim is actually a bit more disturbing than that. Whatever happens in the "outside" world, we tend to think we're somehow inviolate "inside", that this is the true home of the self. But if Buddha and the transcendental phenomenologists are right, then we're wrong about ourselves—profoundly wrong.