Kavka’s toxin puzzle
by James Somers, March 7, 2010
In the January 1983 volume of the journal Analysis, Gregory Kavka presented the following philosophical thought experiment:
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.
It's probably worth asking why this is considered an interesting problem in the first place, since on face there might not seem to be anything difficult going on.
But Kavka seems to think that it would actually be very hard, if not impossible, for someone to intend at midnight tonight to drink a painful poison tomorrow if they knew that they could eventually back out without losing any money. In asserting this he is really taking two steps: first, to argue that a person would never actually drink the poison, because by the time they reach the moment of truth, the prize will have already been won or lost---and no one would choose pain vs. not-pain if all else is equal; and second, to argue that if you knew that you weren't going to drink the poison tomorrow, there is no way you could intend to tonight.
The first step is fairly sound, although one can imagine challenging it in the following way: suppose that you had somehow managed, last night, to intend to drink the poison today---isn't there then a sense in which you're committed to go through with it (such commitment being what initially enabled your intention)? If so, then it may be that to win the money you do have to drink the poison after all. (This was actually the tack taken by philosopher David Gauthier in a paper published shortly after Kavka's. See the Wikipedia page for more.)
It's an interesting possibility that cuts to the core of the problem: can someone intend to drink the poison, and if so, what would such a person look like (epistemologically, psychologically)? Would they be somehow bound, Gauthier-style, to follow through, or is there a way to win the money without having to endure a day of pain?
I certainly don't think it would be the strangest thing to ever happen, and actually I could imagine a few concrete ways you might pull it off:
- You could force yourself to literally forget about the option to back out tomorrow. I doubt I could do this, but there must be some people whose minds are sufficiently powerful (or broken) to selectively "delete" memories. (In which case they would in fact follow through and drink the poison, unless the billionaire reminded them that they had the option not to.)
- More easily, you could construct for yourself a sort of conspiracy theory in which the billionaire is tricking you, and in which you'll have no choice but to drink the poison tomorrow. You could get yourself all riled up this way, momentarily terrified by the prospect, but gradually talk yourself down to the point of acquiescence---"there are no lasting effects; it'll only be painful for a day"---mentally preparing yourself so well to drink the poison that you essentially "forget" about backing out, since that option no longer seems real. This train of thought may sound bizarre, but I'd wager that every day all sorts of paranoid people immerse themselves in far more elaborate fantasies. (And the benefit of pulling this one off is that you would wake up the next day a million dollars richer and amazingly relieved the moment the billionaire let you go.)
- You could be one of those thrill-seekers who thinks it would add to your stock of "life experience" to endure a temporary bout of intense pain. (In this case you probably would end up drinking the poison.)
- Or you could, quite like a regular person, decide that you really want the million dollars and that you'd be willing to endure a day of pain for it. You might then set out to find some way to intend tonight to drink the poison tomorrow, even though you know in the back of your mind that you are very likely to back out. So for the next several hours you might fight yourself, trying hard as you can to eliminate these nagging thoughts of backing out, flitting back and forth between "totally committed" and "knowing full well I won't go through with it." You might even start to consider options like #1-3, but you'd probably dismiss them for being too weird or somehow infeasible. Then finally you'd hit on a brilliant idea: a contract! You have long been telling yourself that "my word is my bond," that you are trustworthy, that other people might renege or cave but that you always come through. You are certain that if you signed a contract with yourself you couldn't break it. And so you'd draw one up, sign it, and sleep comfortably, slightly nervous about the day of painful illness ahead, but pleased to know that you've got a million dollars in the bag. And it would probably be enough to net you the cash. (Of course odds are that the next day you'd go back on your word, but I imagine we all know a few people who really are so steadfast that they'd actually drink the poison.)
There are no doubt many more methods available. The key point is that human psychology is warpable enough to satisfy the billionaire's demands---this is, after all, the same psychology that can willingly kamikaze itself in the name of God or country, that is so often ruled by fear and insecurity, that regularly violates expected utility theory, and that acts, for the most part, as though it's not headed toward an infinite doom.
So the real puzzle here, in my mind, is why Kavka thought this was a "puzzle" at all.
This problem seems related to Newcomb’s Paradox, which seems better structured to present a dilemma. See e.g. http://lesswrong.com/lw/nc/newcombs_problem_and_regret_of_rationality/
Agreed—and I’ve banged my head against Newcomb’s problem quite a bit. (I’m a one-boxer.)
The hardness of the problem, I think, hinges on the meaning of “intention.” If a person “intends” to drink the poison at T0 but then doesn’t follow through at T1, can we say that he genuinely, totally and without qualification, intended to drink the poison at T0?
The schemes you propose may creep close to genuine intention, but I think that on Kavka’s view (not that I’ve actually read his paper), your knowing at T0 that, as you put it, “of course odds are that the next day you’d go back on your word” prevents you from truly intending to drink the poison. In order to truly intend, you need to completely eliminate all possibility of not following through. That is, you need to actually follow through.
I think Newcomb’s problem elucidates the strictness of this type of genuine intentionality. In the formulation of the problem I’m familiar with, the eccentric billionaire nearly always guesses right: regardless of the machinations people employ, nearly all of those who 2-box (regardless of how many boxes they intended to select at T0) end up with the disappointing payoff.
One explanation of the millionaire’s accuracy in this version of Newcomb’s problem might be that the millionaire is a sufficiently powerful demon (of Laplace’s variety) who (1) defines intentionality as your having at T0 one of a certain set of brain states that correspond to your 1-boxing at T1 and (2) knows when you have one of these brain states and when you do not. You might say that what you will do at T1 leaves a residue in your mind at T0, and the demon puts money in the boxes based on the presence or absence of this residue. Therefore, the only way to intend to 1-box at T0 (and thereby get the higher payoff) is to actually 1-box at T1.
Perhaps Kavka thinks it’s impossible to have “gain without pain” in his situation because he’s operating under this strict definition of “intention?”
I completely agree with your analysis if, like you say, “In order to truly intend, you need to completely eliminate all possibility of not following through. That is, you need to actually follow through.” In that case you would be right (and you explained this very well): the problem becomes isomorphic to Newcomb’s and prizewinners at T1 are bound, in a wacky sort of way, to drink the poison (because if they don’t, then it couldn’t have been the case that they won, because their intention wouldn’t have been genuine).
But this simply isn’t what “intend” means! If I tell you tonight that I intend to arrive at dinner on time tomorrow, but then on my way over I get hit by a car (and therefore don’t make it to dinner at all), you can’t claim that I didn’t actually intend to be on time. Intention refers to a plan, and plans are subject to change.
Note that I never said it would be easy to intend (totally and without qualification) to drink the poison at T0 but actually back out at T1. I made a point of describing just how fucked up you’d have to be to pull it off—either because you have bizarre memory problems, or because you’re paranoid and delusional, or because you’re self-destructive, or because you honestly believe you can bind your future self no matter what.
What I mean when I say this isn’t really a puzzle, then, is that it’s not philosophically difficult in the way that Newcomb’s problem is, at least when you interpret intention in its regular everyday sense.
So I take it that the only way you could intent and not do it is with independent external interference, e.g. from another person or event, which the poison drinker did not initiate.
E.g. a friend accidentally heard about it and decides to stop you without your prior knowledge. If you tell him to stop you it would not be an honest intention. The “paranoid” scenario is a bit too far fetched as a realistic work-around.
If you’re allowed to sign contracts, surely this is relatively straightforward. Just sign a contract promising to donate $1 million to [whatever charity you don’t like] if you don’t drink the poison tomorrow afternoon. Don’t make this contract conditional on the billionaire giving you the money, and you’ll have to intend to drink the poison.
I would offer a close friend (or perhaps a stranger) a chunk of the money on the condition that he forced me to drink the poison the next day, and I wouldn’t tell him why. If that’s unworkable (since I’m planning on telling him) I’d ask him to find someone to poison me without talking to me, and so on.
So…I’d probably end up drinking the poison. But I’d definitely get the million dollars.
The catch-22 is telling you that you can change your mind, thus eliminating the option of being able to change your mind. In order for you to truly change your mind, you’ll need to get new information during the time when you decide to commit to drinking it and the time it takes to drink it. For example, you can commit to drinking it, but find out that it’s made from nuts which you’re deathly allergic to and it will kill you. Since the only stipulation is to drink the vial of poison, you can intend to drink it, but also intend to alter it in a way to be less painful or not painful at all. Perhaps heating it, or adding another substance to it to lessen the effects. Add a substance that absorbs the substance completely so it will not interact with your chemistry. Then when you drink/eat it, you have proven your intent to drink it. Then again, drinking it doesn’t prove you intended to drink it at midnight, so the act of actually drinking it shouldn’t matter either. The billionaire isn’t asking for proof, so really intent doesn’t matter either. Just agreeing to the condition should be enough to get you a million dollars. It’s only when you add more information not asked for that will screw it up for you. All you need to do is say “Yes” and “Thank you” after you get the money.
I believe the problem is too simply stated to determine any conclusive course of action.
The whole issue of acquiring the money rests on the billionaire’s assessment of your intent and his conviction that you will follow through. There is no way that actual intent can be concretely determined in the perception of an outside observer. The entire problem hinges the subjective understanding of the participants at the time the deal is made. Any third party speculation introduces an almost infinite number of variable conditions that can never be resolved.
The only solution is for each individual considering the problem to actually face the real-life prospect of making the deal.