Teleportation
Suppose a device is created which would vaporize the atoms and molecules that form your body, transport them to another place in the world, then reassemble them exactly the way they were. Let's call this procedure type-A teleportation (this is a distinction I am making up, and it will be clear later in this post why it is necessary). We sometimes see these kinds of teleportation devices depicted in science fiction and fantasy. They are also occasionally mentioned as a thought experiment in the philosophy of personal identity , which is the branch of philosophy that revolves around, among other things, the question, "What makes you the same person you are at another time?" We might answer that we know we are the same person we were yesterday because we have the same memories as the person yesterday. Let's call this the psychological account of personal identity . The psychological account is worrisome because memories and human psychology are fickle things. Say y...