Hi everyone. I’m the new director of the We Thinks Good philosophy discussion group. Today I’m going to talk to you about personal identity, which is the theme of the next meeting. And I’ll try to keep it short.
What is personal identity? Relatedly, what does it mean for your personal identity to persist from one moment to the next?
One popular theory is that your personal identity resides in your psychological states, and so your personal identity persists over time just as long as your psychological states persist over time.
Derek Parfitt has challenged this theory by introducing a number of thought experiments that cast doubt on our intuitions about out personal identity, particularly the notion that our personal identity resides in our minds rather than our bodies.
Imagine that you’re visited by some aliens who inform you that your planet is going to be destroyed in a nuclear Holocaust in the next year, but they can save you by teleporting you onto their space ship. You’re about to agree to this generous offer when the aliens explain how the teleportation device works. It works by eviscerating your current material form and replicating it at your destination. That is, it’s like a biological photocopier that automatically destroys the original.
When the aliens see the look of horror on your face, they assure you that your personal identity – your self – will most definitely persist through the teleportation process, even though your current material form will be destroyed. It’s not a death machine, they assure you; it’s just a convenient mode of transportation.
To the aliens’ surprise, their assurances don’t convince you.
So, the aliens give you a second option. Instead of teleporting you to safety, they’ll replace your biological cells with mechanical analogues that can withstand the force of a nuclear blast, thereby allowing you to survive the nuclear Holocaust. And since they know you’re not keen on instant evisceration, they offer to replace your biological matter gradually – over the course of a year.
When the aliens see that you’re still not satisfied, they start to think that you’re quite irrational. What could be wrong with gradually replacing your biological cells with mechanical analogues, when all the cells in your body are naturally replenished by biological processes in a matter of weeks? What’s the difference between mechanical substitution and biological substitution?
At this point the aliens are becoming quite perplexed by the ostensible irrationality of the human mind, but they try one last solution. They will transplant your entire brain into a host body capable of withstanding a nuclear blast. This host body will be partly mechanical, and its mechanical parts will protect your frail biological brain, to which you are so irrationally attached. The host body won’t be identical to your current body, though. The aliens have carefully studied human preferences and have produced a set of identical host bodies based on their research. All of the host bodies are exact replicas of Brad Pitt circa 2003, as their research has revealed that human beings show a decided preference for white males with muscular exteriors and other stereotypical masculine attributes. Therefore, all of their host bodies are exact replicas of 40-year-old Brad Pitt.
When the aliens see that you’re still not satisfied, they start to fear that human beings aren’t even an intelligent species.
“What’s wrong now?” they ask. You explain that Brad Pitt is a man and you’re a woman. That is, Brad Pitt’s body doesn’t fit with your gender identity. Therefore, transplanting your brain into Brad Pitt’s body won’t fully preserve your personal identity. The aliens don’t know what you’re talking about, as they come from a genderless society. They don’t understand why you would care about gender, let alone whether your gender presentation matches your gender identity. After all, gender is just a social construct that human beings made up. You try to explain that just because something is a social construct, that doesn’t mean that it’s not real. Money is a social construct but money is so real that people die without it. But the aliens just roll their eyes.
How will you escape the impending nuclear Holocaust with your personal identity fully intact? Can you?
To find out, please join me at the next meeting of the We Thinks Good group (October 6 from 3-4:30pm).