Suppose that I am driving at midnight through some desert. My car breaks down. You are a stranger, and the only other driver in this desert. I manage to stop you, and I offer you a great reward if you drive me to my home. I cannot pay you now, but I promise to do so when we reach my home. … If you drive me to my home, it would be worse for me if I pay you the promised reward. Since I know that I never do what will be worse for me, I know that I would break my promise. Given my inability to lie convincingly, you know this too. You do not believe my promise. I am stranded in the desert throughout the night.

— Derek Parfit, Reasons and Persons, 1984