Kavka's Toxin Puzzle
Suppose you get the following proposal from an eccentric billionaire:
"Toxin X is a substance that will make you violently ill for a few hours. However, it has
no long term effects of any kind. As an experiment in psychology, I'm offering you a million
dollars if tonight at midnight you fully intend to drink toxin X by tomorrow at noon. You don't
actually have to drink the toxin; all you have to do is to intend to drink it. Your intention
will be tested by a device similar to a polygraph which my people have developed and which has
been shown to be 100% accurate. If at midnight you have the intention, a million will be
wired to your bank account. The only other conditions are that you are to make no bets, do
anything that will cause you to become irrational, or arrange for any way to avoid the effects
of the toxin."
Suppose you decide that being ill for one day is a reasonable price to pay for a million
dollars. Your first thought is to therefore agree to the proposal. It then occurs to you that
you won't even have to become sick in order to win the money. All you have to do is to intend
to drink the toxin. You don't actually have to carry out your intention.
But now if you know ahead of time that you don't actually have to drink the toxin, then you
can't really intend to drink it. So you tell yourself you really do have to drink it. But then if
at midnight you really did intend to drink the toxin, and you got the million, then come the next
day you would no longer have any reason to drink it: you've already been paid and drinking the
toxin would make you unnecessarily sick.
Is there any way for you to win the money?
See also Newcomb's Paradox
©2000 Franz Kiekeben