Kavka's toxin puzzle

Kavka's toxin puzzle is a thought experiment about the possibility of forming an intention to perform an act which, following from reason, is an action one would not actually perform. It was presented by moral and political philosopher Gregory S. Kavka in "The Toxin Puzzle" (1983), and grew out of his work in deterrence theory and mutual assured destruction.

The puzzle

Kavka's original version of the puzzle is the following:

An eccentric billionaire places before you a vial of toxin that, if you drink it, will make you painfully ill for a day, but will not threaten your life or have any lasting effects. The billionaire will pay you one million dollars tomorrow morning if, at midnight tonight, you "intend" to drink the toxin tomorrow afternoon. He emphasizes that you need not drink the toxin to receive the money; in fact, the money will already be in your bank account hours before the time for drinking it arrives, if you succeed. All you have to do is. . . intend at midnight tonight to drink the stuff tomorrow afternoon. You are perfectly free to change your mind after receiving the money and not drink the toxin. [pp. 33-34 in Kavka, Gregory, "The Toxin Puzzle" "Analysis", Vol. 43, No. 1. (Jan., 1983), pp. 33-36.]

A possible interpretation: Can you intend to drink the toxin, if you know you don't have to?

The paradox

The paradoxical nature can be stated in many ways, which may be useful for understanding analysis proposed by philosophers:
* In line with Newcomb's paradox, an omniscient pay-off mechanism makes a person's decision known to him before he makes the decision, but it is also assumed that the person may change his decision afterwards, of free will.
* Similarly in line with Newcomb's paradox; Kavka's claim, that one cannot intend what one will not do, makes pay-off mechanism an example of reverse causation.
* Pay-off for decision to drink the poison is ambiguous.
* There are two decisions for one event with different pay-offs.

Since the pain caused by the poison would be more than off-set by the money received, we can sketch the pay-off table as follows.

One of the central tenets of the puzzle is that for a reasonable person
* There is reasonable grounds for that person to drink the toxin, since some reward may be obtained.
* Having come to the above conclusion there is no reasonable grounds for that person to drink the toxin, since no futher reward may be obtained, and no reasonable person would partake in self-harm for no benefit

Thus a reasonable person must both intend to drink the toxin by the first argument, yet if that person intends to drink the toxin then they are being irrational by the second argument.

See also

*Mutually assured destruction
*Newcomb's problem
*Prisoner's dilemma

References