Kavka's Toxin Puzzle
An eccentric billionaire offers you a deal: intend, tonight at midnight, to drink a vial of toxin tomorrow that will make you painfully ill for a day but cause no lasting harm. If you genuinely form that intention, a million dollars appears in your account by morning — and you're free to change your mind afterward and never drink it. Can a purely rational person form that intention, knowing they'll have no reason to follow through once the money is already theirs?
Reveal the answer
Philosopher Gregory Kavka argued no — not through ordinary willpower. A rational person can see in advance that once the money is secured, drinking the toxin serves no purpose, so there's nothing to genuinely intend beyond self-deception or a binding commitment. Yet the reward is offered for the intention, not the act, which seems to make forming it the obviously rational move. Kavka published the puzzle in 1983 to probe whether intentions can be freely willed the way beliefs can't.