"Then how do you know it was really me?"

Very cool little thought experiment...

Phone Calls From The Future » Pop Occulture:

"Here’s a fun speculative scenario I was talking about with a friend of mine last night. Imagine for a moment that you received a phone call from yourself in the future. First of all, how would they prove that they were really you, and second, how would they be able to prove they were from the future? So maybe they know secrets about your life - but maybe that just makes them psychic and manipulative. Is there any way to be sure you’re really talking to yourself? If you were somehow sure, would you flip out? I think I would. I think I would be terrified actually.

...that probably means that you’re about to be told to do something that you won’t like or understand. When you ask for an explanation, they’ll probably give you one which further strains your credulity over the whole situation - which would be too risky given the delicacy of the situation. So more than likely, you’ll tell yourself that you can’t say why. You’ll hear yourself say, “Just trust me.”

If that was the case, would you go ahead and trust yourself? What if you weren’t sure yet if it was really you? What if it was some kind of alternate-dimension/trickster version of yourself trying to get you to do something stupid or dangerous? Would you have any choice but to ignore their advice and carry on as before?

If you determine that you can’t trust yourself in the future, on what grounds should you therefore trust your current self? How do you know you’re really yourself? Reminds me too of a fun Sufi parable where Nasrudin walks into a shop, and the shopkeeper says, “Can I help you?” Nasrudin asks: “Did you see me come into the store just now?” To which the shopkeeper answers yes. Nasrudin replies, “But have you ever seen me before?” When the shopkeeper says that he has not, Nasrudin rebuts, “So then how do you know it was really me?”"