Why do you do what you reject?

You know you should go to sleep. You know the message you're about to send will make things worse, and that the third slice is a mistake. You do it anyway, and you knew the whole time. Or did you? Socrates said you didn't. In Plato's Protagoras he argues that nobody does wrong while seeing clearly that it is wrong. What looks like weakness is an error of measurement, like a near object looking bigger than a far one: the pleasure in front of you looms large, tomorrow's cost looks small, and in that moment you misjudge. Teach someone to measure properly and the behavior follows. Aristotle thought this flew in the face of what plainly happens, and studied the condition closely under the Greek name akrasia, usually translated as weakness of will. His answer was subtler than a flat no. The person knows in one sense and not in another, the way someone drunk can recite lines of poetry without grasping them. Desire doesn't erase the knowledge. It puts it to sleep. Even so, he granted Socrates part of his point: what desire overpowers is not knowledge in the fullest sense. The poets have mostly sided with experience. Ovid's Medea, falling for the man who will ruin her, admits she can see which course is better and takes the other one anyway. Paul, writing to the Christians in Rome, describes wanting the good and doing the evil instead. And Augustine remembers asking God, as a young man, to make him chaste, but not right away. Think of the last time you did it anyway. In that moment, what did you actually believe?