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What makes you... you

Posted on:October 28, 2015 at 07:17 AM

You’re probably not who you think you are…

A philosophical inspection of the notion of personal identity

So what is a personal identity? What is it that makes you who you are?

There are a couple ways to go about defining this initially rather abstract and humanly invented concept. You first must decide what it is that determines who you are. Is it you? Well it would have to be, although your parents do decide the most crucial part of your identity, which is your name.

Hrmm… what is a person?

Well, let’s look at it from a more literal perspective. I am a person, with a body, and a “mind” that is resultant from the functions of my brain and my subconscious. But let’s abstract the neuroscience from the matter and simply say, that a person consists of the contents of your brain, which I will colloquially refer to as the mind, and a body. A person consists of a mind and body.

What is it for each of us to exist? Which properties, if I lost them, would mean I would no longer be what I am?

portrait of descartes

a portrait of Rene Descartes, courtesy of elephant learning

We’re working with a definition of a person as a combination of your body and your mind. So which is essential to the notion of personal identity? Is it your brain or your body that determines who you are?

Let’s examine both ideas, and see what we end up with.

If it were in fact the physical body that determined who you are… what would this mean?

On the body…

Let’s look at a slightly contrived example, let’s look at the hypothetical Amy and Brian. Both have bodies, and both have minds. What if we switched their minds? Who is who? Well, Amy now has Brian’s mind, and all the thoughts and ideas of Brian. Brian also has Amy’s mind, and so we would consider them now to be each other? Certainly most of the people they know might not notice the difference until after talking for a little while.

More interestingly, what if we cloned someone.

But this is a bit of a contrived example and doesn’t happen in the real world.

Which brings us to things like accidents, or, more generally changes to the physical body. What happens when people’s bodies change? We define Sarah to be Sarah at any given time based solely on the fact that Sarah’s body is there. But what if Sarah experiences some tragic accident and no longer has an arm, or becomes handicapped in some other way? The body has changed, but has the person changed? Frank isn’t somehow not Frank just because he broke his leg.

This must mean that it is the mind that actually determines what someone’s personal identity is, and this is certainly the more intuitive viewpoint, however there are some problems that come with this viewpoint as well.

On the mind…

Imagine then, the very simple example. Derek is who he is, because of the contents of his mind right now.

What about tomorrow, what if his opinion changes, or he learns something. And there are still of course the accidents that affect the brain that result in a very changed personality. Do people with slightly changed brains or ideas have the same exact mind? Probably not. In which case that would mean they are by definition not the same person. But we certainly don’t do that. On the day to day we still refer to each other as the same people.

There’s yet another problem that also arises. What if you were able to create a computer, (and this technology exists) that could perfectly replicate a person’s reactions to certain stimuli and ideas? This computer could effectively recreate the mind of a person. Surely the computer is faster, but what would that mean for our person? Which entity is more you?

Modern philosophers actually refer to things like names as a convenient illusion for personal identity. Because the concept itself is actually incoherent. These complex problems have resulted in a very interesting modern definition for what personal identity actually is.

Personal Identity: the persistent and continuous unity of the individual person normally attested by continuity of memory with present consciousness.


If you’re interested in further reading on the nature of personal identity in philosophy, try checking out Stanford’s dictionary of philosophy on the subject.

There is also an absolutely fantastic paper on this entitled, “Where am I” by Modern Philosopher Daniel Dennet on the notion of personal identity.