This is the second part of a two-part series focused on personal-identity—what it is and how we can define it. In the first article, we recapped that identity cannot be tied to something merely physical, and therefore there must be some mental component that engages in the construction of the personal identity. We also covered, and disproved, John Locke’s theory that personal identity is simply a continuation of experiences of memories.

Another theory regarding personal identity involves the existence of an immaterial soul. This was Cartesian view, developed by Rene Descartes in the 17th century. Descartes, who I covered earlier in the blog, was a substance dualist, who saw two fundamental entities—body/physical matter, and mind. He famously concluded, Cogito, Ergo Sum (I think therefore I am), meaning that he saw himself as a thinking thing, not necessarily a physical body. In Descartes view, people are the same individual over time, because regardless of how their body changes, they have the same immaterial soul. People can age or change over time, but as long as the soul persists, the person is the same. However, this itself runs into another problem, similar to the problem one would discover if they read my paper on mathematical platonism: if we regard the soul as an immaterial, abstract concept, it is impossible for us to perceive, and therefore, impossible for us to verify.

This is where modern philosophers such as Derek Parfit take issue with the cartesian theory. If we just say that the soul is an immaterial aspect of our personality, it still leaves us with a whole lot of guesswork to determine what the thing actually is. Like many solipsist-esque views, it is certainly not a satisfying or intuitive answer, yet we cannot strictly disprove that it exists. Parfit says that if we solely define our identity as a “soul”, it really gets us no closer to the answer. We say our identity is a soul, which leaves us with the easily solvable question of “what a soul is”… So, it is silly to simply identify our identity as a soul, if we have no conception of what that soul is.

If we have no good evidence to prove that our personal is a collection of memories or experiences, and we have no good evidence that our personal is some immaterial, abstract soul, could it be that our personal identity is merely a bundle of perceptions that gradually change over time, so gradually, that we assume they are actually something immovable? This was the view developed by British Empiricist David Hume. The Humean view posited that we were merely collections of sensations, thoughts, memories, and desires, that constantly changed over time. According to this view, the notion of an irrevocable personal identity is merely a linguistic or cultural figment of the imagination that has developed for ulterior reasons, like responsibility or morality. This also seems like a deterministic idea: if we truly have no personal identity, and are just a bundle of senses, how can any of us have responsibility over our actions. In Hume’s view, when we say “I,” we are really just referring to this ever-shifting cluster of experiences, not some deeper, unchanging self.

Hume came to this view when he looked inwards: he claimed that he never found a stable “self,” only perceptions—like heat, cold, love, hate, pain, pleasure. This lead him to conclude that if we can never perceive the self apart from perceptions, then the self is not something above the senses at all, merely, it is just something that has developed within them. Hume described the mind, and therefore personal identity as a theater. Different sensations, ideas, feelings, thoughts constantly flash through. Yet you are not the theater director, but in the audience, observing the passing scenes fly by. Of course, the problem with any of these theories that decree personal identity to be nonexistent run into the problem of arguing against intuition. Even when I wrote this paragraph, I referred to Hume and myself as people—not clusters of ideas and sensations. As this is so ingrained into our linguistic tradition, it requires serious explanation of how or why we feel that there is an “I”, when in reality, according to Hume, that is false. Hume runs into another problem: ownership. Who is it that controls the bundle, that has the bundle, that at least holds the bundle of sensations temporarily before they fly away. Could this in itself prove the existence of a personal identity, or can this be explain by mere physical dimensions?

Hume’s view offers an answer to one of the fundamental problems of personal identity—what I’d call the problem of change. We all change throughout our lives, yet we still insist that we have a core identity. This raises a tricky question: if our identity changes with us, how can we be sure we remain the same person? Even thinking about it is paradoxical. It is admitting that your core identity has shifted, but saying that you remained the same inside. This does not make sense, unless you play some crazy mental gymnastics by insisting the reason you changed was because of your core identity that you’ve already had. But this regresses infinitely, and the logic reduces to the statement that you must’ve had the same core identity as a newborn as you have now… Definitely not logical to me.

In conclusion, it seems we are left with two far-reaching extremes: believe in the unintuitive answer that personal identity is false, or struggle to come up with defining criteria for what personal identity is. It’s all up for debate.