There have been a lot of jokes based upon the old expression, "I'm not myself today". If your questionable identity should be any more than simply an adage, you would have to ask, then, who you actually are. Likewise, the idea has been the springboard for a lot of stories. Off the top of my head, I can think of several episodes of The Twilight Zone from the 1960s that took advantage of the possibility: "A world of Difference", "Mirror Image", "Person or Persons Unknown", "The Four of Us Are Dying", "Five Characters in Search of an Exit", "Death Ship". There are probably more, but my memory is finite. And I can think of an episode of the The Outer Limits (the original; I was never crazy about the HBO clone except for a couple of episodes), not where someone doesn't know who he is, but where no one else does: "One Hundred Days of the Dragon", and one where two people exchanged minds: "The Human Factor". Identity is pretty flexible in the world of speculative fiction.

If you're not yourself, then there are only so many options. You're somebody else. Somebody else is you. You're dead and don't know it ("Death Ship"). You're a duplicate of the original without knowing it. And I suppose possibilities with no real explanation, like "Mirror Image". Welcome to the world of cybertech, where we have options that didn't exist during the '60s: you're a computer simulation (think "Matrix") or a computer game character (think any of dozens of anime). In fact, scientists and philosophers are seriously considering the possibility that we are computer simulations.

But wait, the possibilities are not exhausted yet. I used this quote from Korvoros in another post of this series dedicated to teleportation, but let me repeat it here:

“So let’s proceed to utter insanity,” she continued. “If the information is all that’s important, suppose that two receiving stations happened to pick up the signal and each one makes a new instance of you. Which would be the real one? Or would either of them really be you? You could be dead and they could be fakes that no one could tell from the original because all the memories are duplicated too.”

So you haven't traveled by teleporter lately? Well, you're not off the hook. Suppose that every time you have even the slightest impure thought, your soul is immediately sent to hell, whereupon another soul with all your memories immediately takes its place. You could be 270,000th "you", just waiting for that impure thought to send you away. Since all the memories are duplicated, how could you possibly know? Since you're exactly the same, how could anyone else possibly know? Maybe the impure thought isn't necessary. Maybe we're all rebooted once a second regardless of what passes through our minds and our "true" identity lasts no longer than that.

One of my short stories that I haven't finished involves a police investigator who is actually one of a series of robots created by other robots to replace living people, only a defect in the manufacturing left the first run not knowing they were duplicates.

So you woke up this morning with the smug assumption that you are the same person you were last night. You can't be so sure of that, can you? That person could be gone forever.

From this point, let your mind wander. Is there some other way you might not be you? Some way that I've overlooked? If so, I'd be interested to hear about it.