"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?

This paradox is more complicated than I originally suspected.  If we take intention to mean that state of mind whereby one governs one's free will in accordance with the future outcome of a desired result, we must consider how one would react to the obvious dilemma of not having to take the poison at 12:01 a.m.  Those who do employ that ethical consideration in the making of such decisions, and who can also trust their promise as the fulfillment of an action as yet to be committed, won't have a problem merely subjecting themselves to the polygraph and drinking the poison at noon the next day.  However, those who rationally consider that even their strongest intention to drink the poison will fail precisely when they receive the money credited to their account, will (in order to secure the funds) construct a situation in which their lack of resolve to carry through with that irrational act is thwarted either through physical force or through a third party who will take possession of the funds (the principle motivation) should the person fail to drink the poison at noon.

Interestingly enough, the first two of these solutions involve subjecting the person to circumstances that disallow their future choice to reject the possibility of not taking the poison after the polygraph is taken.  For the moral man who can trust that his promises are sufficient enough to counter the effects of a waivering will, his own sense of ethics introduces an external outside force that overrides his personal and "rational" desire not to take the drink.  I'm not sure it is made clear in this problem if this 100% accurate polygraph will go off even if it's more probable that the person will take the poison, but it seems to me that as this external force is in itself a subjective assumption about the character of the person, it should be capable of being detected.  I'm sorry to introduce my own personal theological views on the matter, but for the problem itself, I only see Jesus passing this test, and there's no way His glory would would find himself in such a situation to begin with.

That would place everyone in the second category, that is in the vast majority of people who either cannot trust their ethics to override their "rationality" or who have no such ethical standards to begin with.  In the second case, we again see the employment of an external, outside force (strongmen, locked doors, funnels and hoses) that again ultimately succeeds in overriding their personal desire not to take the poison.

In the third and last case (by far my favorite and I believe the real solution to this problem), if the person shifts the motivation from merely passing the polygraph and not taking the poison, to getting the funds if and only if they do take the poison (i.e. a legal witness either verifies that the poison was drunk and a second party gets no money, or verifies that the poison was not drunk and a second party collects all of the money) they neatly transform this problem into a simple decision of drinking or not drinking to win the million.

I'm exhausted writing this, Sam...  It's an intruiging problem, and I still don't think I've arrived at any real answer to the question:  Is it possible to take the money and not drink the poison?

More thoughts and brain power welcome.