Whilst searching through his philosophy notes Lewis found a note from his younger self.
“Enjoy the exam sucker, I spent all my time playing Skyrim instead of revising!”
Yep, his future self sure was in trouble now; but then what did he care, it wouldn’t be him sitting the exam.
Identity over time is a rather perplexing thing: Throughout our lives we change quite dramatically, in size, shape, in our ideas, our ambitions; even the matter that makes us up is different from one year to the next. And yet, we are certain that we are the same person at all moments in our lives, that there is a continuity from the baby that was born in the past, to the person reading this in the present and then on the the person taking their last breath on their deathbed somewhere in the (hopefully distant) future.
But what is it that makes us the same person as the one that existed yesterday, or ten years ago? It’s not a case of matter, as already noted, because our bodies are almost constantly changing the material that they’re made from. Similarly it can’t be the cells that we’re made up of, as they get replaced over the course of months. We might try to account for identity over time in terms of memory (I am the same person as I was yesterday because I have memories of being me yesterday) but then we don’t tend to remember things from early on in our lives, and what about drunken nights out where you remember nothing? Does the fact that you don’t remember your behaviour mean it wasn’t you issuing it? I doubt many people are going to find that defence too convincing (‘Well sweetheart, someone cheated on you, but I don’t share their memories so it wasn’t me; in fact, if you were in a relationship with them then technically you’ve been cheating on me!).
Why shouldn’t we think of ourselves as a different person from one moment to the next? Perhaps we genuinely don’t escape the moment that we are currently in and it’s someone new that takes over, thinking they are us (just as we took over from someone else before). Presumably we need some sort of conception of identity over time in order to get anything done: If you don’t associate yourself with someone in the future, then you aren’t going to put yourself out to make their life easier (why should I exercise and get into shape for someone else? Why should I endure hardship now if it won’t be me that gets the benefits?) But the fact that identity over time is useful for a person seen as a four-dimensional whole, or for the human species in general, doesn’t mean that we actually are the same person from one day to the next. Perhaps we should all just be making sure our present is as good as possible, given that we might not make it into the future.
Sometimes I think I really am not the same person I was just a couple of years ago. I have nothing in common with my younger self, my way of thinking, my attitude towards myself and others, towards relationships, towards religion, they’re all different. Maybe I am just a different person, unaccountable for the mistakes of that person in the past, only loosely the same person. I once did write a letter to my future self, whilst I was (supposed to be) studying for my A levels. I didn’t want to work, the exams were too far off and I couldn’t really imagine myself being in the exam room taking the exam, so I didn’t revise. But I did write myself a little note, something like ‘To my future self, I’m having fun back here instead of revising, enjoy the exam!’ It was an odd experience reading it, I felt a disassociation from myself, as if I genuinely were reading the writing of someone other than me. You get a similar feeling when you read very old essays you’ve written and realise how different you are now. Try it: write your future self a letter, if you don’t escape the moment, at least your thoughts will…
(TL;DR: Are you the same person as you were three years ago? If not, then why do things now that only benefit your future self?)