The Philosophy of Shapeshifters, Socks, and Personal Identity

By Martin Cohen

Perhaps the proudest achievement of philosophy in the past thousand years is the discovery that each of us really does know that we exist. In a way, Descartes proved that with his famous phrase:

“I think therefore I am”

It is unfortunate then, that there is a big question mark hanging over the word “I” here – the notion of what philosophers call “personal identity.” The practical reality is that neither you nor me are in fact one person, but rather a stream of ever so slightly different people. Think back ten years – what did you have in common with that creature who borrowed your name at that time? Not the same physical cells, certainly. They last only a few months, at most. The same ideas and beliefs? But, how many of us are stuck with the same ideas and beliefs for the long run? Thank goodness these too can change and shift.

In reality, we both look, feel, and most importantly, think very differently at various points in our lives.

Such preoccupations go back a long, long way. In folk tales, for example, like those told by the Brothers Grimm, frogs become princes –or princesses; a noble daughter becomes an elegant, white deer, and a warrior hero becomes a kind of snake. In each of these cases, the character of the original person is simply placed in the body of the animal, as though it were all as simple as a quick change of clothes.

Many philosophers, such as John Locke, who lived during the seventeenth century, have been fascinated by the idea of “shapeshifting.” These philosophers consider shapeshifting to be an important notion, raising profound and subtle questions about personal identity. Locke himself tried to imagine what would happen if a prince woke up one morning to find himself in the body of a pauper – the kind of poor person he wouldn’t even notice if he rode past them in his royal carriage on the street!

Locke discusses the nature of identity in his Essay Concerning Human Understanding. He uses some thought experiments too as part of this, but not, by the way, (per multiple queries!) the sock example. It is commonly believed that Locke posed a question regarding how many repairs he could make to one of his socks before it somehow ceased to be the original sock,known as Locke’s Socks. However, he does talk about a prince and a cobbler and asks which “bit” of a person defines them as that person. In a chapter called “Of Identity and Diversity” in the second edition of the Essay Concerning Human Understanding, he distinguishes between collections of atoms that are unique and something made up of the same atoms in different arrangements.

Living things, like people, are given their particular identity not by their atoms (because each person’s atoms change regularly), but rather are defined by the particular way that they are organized. The point argued for in Locke’s famous Prince and the Cobbler example is that if the spirit of the Prince can be imagined to be transferred to the body of the Cobbler, then the resulting person is really the Prince.

More recently, a university philosopher, Derek Parfit, has pondered a more modern–sounding story. His idea contemplates the possibility of doctors physically putting his brain into someone else’s body in such a way that all his memories, beliefs, and personal habits were transferred intact. Indeed today, rather grisly proposals are being made for transplants like this. But for philosophical purposes, Derek adds a fiendish touch and questions what would happen if it turned out that only half a brain was enough to do this kind of “personality transfer?”

If that were possible, we could potentially make two new Dereks out of the first one! Then how would anyone know who was the “real” one?!

Okay, that’s all very unlikely anyway. And yet, there are real questions and plenty of grays surrounding personal identity. Today, people are undergoing operations to change their gender – transgender John becomes Jane. Chronically overweight people are struggling to “rediscover” themselves as thin people. Or are they a fat person whose digestion is artificially constrained? Obesity and gender dysporia raise profound philosophical questions.

On the larger scale, too, nations struggle to determine their identity – some insisting that it involves restricting certain ethnic groups, others claiming that their identity rests on enforcing certain cultural practices. Yet the reality, as in the individual human body, is slow and continuous change. The perception of a fixed identity is misleading.