The “bundle theory,” as it’s sometimes called, has become increasingly attractive as science has steadily whittled away at the idea of the core self. The philosopher Derek Parfit, for example, has argued that we have no self at all, but merely an overlapping succession of mental states—a variation on Hume’s theory that has become moderately famous, in that it is perhaps the only philosophical conception of personal identity to be extensively discussed in The New Yorker. What is particularly interesting, though, is Parfit’s description of his personal reaction to the realization that he didn’t need a unified self. That response appears in a section of his (massive) treatise Reasons and Persons titled “Liberation from the Self”:

Is the truth depressing? Some may find it so. But I find it liberating, and consoling. When I believed that my existence was such a further fact, I seemed imprisoned in myself. My life seemed like a glass tunnel, through which I was moving faster every year, and at the end of which there was darkness. When I changed my view, the walls of my glass tunnel disappeared. I now live in the open air. There is still a difference between my life and the lives of other people. But the difference is less. . . . I am less concerned about the rest of my own life, and more concerned about the lives of others.

In the yellow wood, he has seen the roads diverge, each inclining, as Frost once put it, toward “black and utter chaos,” and realized that there is really no “I” to feel trapped and fearful. That is a good thing, to be sure. And yet the primary attraction of this passage isn’t its logic, but the throb of emotion that propels its lines into arcs of metaphor (“My life seemed like a glass tunnel,” “I now live in the open air”). One hears in these oddly poignant statements not the impersonal sound of the self being diminished, but the familiar music of a particular self being transformed.

But what exactly is being changed? One of the problems with the self—whether modeled by Frost or theorized by neuroscientists—is definitional. When we say “the self,” are we talking about a self-conception? Consciousness? A kind of personal narrative? There is a tendency, even among the most careful thinkers, to overlook the fact that when the average person talks in a way that implicates the self, that person often says things that seem to refer to very different aspects of identity. For instance:

• I don’t feel like myself today.
• There I am! [while looking at photos from childhood]
• Yes, I moved your coffee cup.

These are all ways of invoking an “I,” and yet they seem only lightly tethered to one another. Is the “I” who moves a coffee cup really the same “I” who appears in a thirty-year-old picture? And if not, does it make sense to call them both “the self”?