And just before the final operation, your brain would be a 99 percent replica. Would the self at the end of this series of operations still be you, even though your original brain had been completely destroyed and replaced? And if it ceased to be you, at what point in the series did you suddenly disappear and get replaced by a new self?
It looks as if neither the psychological criterion nor the physical criterion decisively settles who I am. This raises a disturbing suspicion. Perhaps there is no fact of the matter when it comes to my identity. Perhaps there is no real answer to the question of whether I exist or not. Even though I am referring to something when I say “I” or “me,” that something has no ontic solidity. It does not figure among the True and Ultimate Furniture of the Universe. It has no existence apart from the constantly shifting mental states that populate my mind and the constantly changing set of physical particles that constitute my body. The self is, to use Hume’s analogy, like a nation; or, to use Parfit’s analogy, like a club. We can keep track of its identity from moment to moment. But the question of whether it remains the same over long stretches of time, or through great physical and psychological discontinuities, is an indeterminate, even an empty one. The enduring, substantial, self-identical I is a fiction. As the Buddha put it, the self is “only a conventional name given to a set of elements.”
Hume found this conclusion, convinced though he was of its truth, to be a depressing one. It left him, he wrote, “in the most deplorable condition imaginable, inviron’d with the deepest darkness.” (Fortunately, he was able to find relief by playing backgammon with friends.) By contrast, Derek Parfit, rather more like the Buddha, finds it “liberating and consoling.” Before, when Parfit thought that the existence of his self was a deep all-or-nothing fact, “My life seemed like a glass tunnel, through which I was moving faster every year, and at the end of which there was darkness.” Once liberated from the self, however, “the walls of my glass tunnel disappeared. I now live in the open air.”
Suppose that the Cartesian I—the I of “I think, therefore I am”—truly is an illusion. How could such an illusion arise? (And, one might want to ask, for whom or what is it an illusion?) Well, to be an I is to have self-consciousness, to enjoy the power of reflexive awareness. So perhaps the I is conjured into existence in the very act of thinking about itself. Perhaps, in other words, the I is self-creating!
Such was the daring hypothesis that Robert Nozick put forward, albeit “with great hesitation,” to deal with the otherwise “quite intractable” problem of the source of the self. According to Nozick, when the Cartesian says, “I think,” he is not referring to any preexisting entity. Nor is he truly describing an already existing state of affairs. Rather, the state of affairs is made true by the declaration. The entity referred to by the pronoun “I” is (somehow) delineated in the very act of self-reference, which picks out “the thing of greatest organic unity” that includes the act itself. And what are the boundaries of this organically unified self-creation? “Nothing we have said thus far limits what the self-synthesizing self can synthesize itself as,” Nozick observed. He even entertains the possibility that this self might be “identical with the underlying substance of the universe, as in the Vedanta theories that Atman is Brahman.”
Once you entertain the notion that the I is self-creating, it’s easy to find yourself sliding down a slippery transcendental slope. And what lies at the bottom of that slope is a curious form of idealism, one which says that the I, in creating itself, creates all of reality. Daft as this notion might sound, it crops up repeatedly in European philosophy after the time of Kant. Versions of it can be found in Hegel, Fichte, and Schelling in the nineteenth century, and in Husserl and Sartre in the twentieth century.
Take Johann Gottlieb Fichte, the son of an impoverished ribbon-weaver who grew up to become not only the esteemed philosophical successor to Kant but also the intellectual father of German nationalism. Fichte held (like Nozick) that the I leaps into existence in the very act of “positing” itself. The statement “I = I,” being an instance of the logical law of identity, is a necessary