"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?

It is very easy to have every intention to do something that you are reasonably sure you won't have to do. After all, don't people swear to be faithful to their wife/ husband and really believe that they will, only to later divorce them?

The human mind finds it very easy to deceive and lie to itself; to even convince itself utterly that something exists that doesn't or that something will happen which won't. Any of us with a little will power can do this just fine.

In this case it would be a simple enough thing to tell yourself: "I intend to drink the potion. They might not require it of me in the end, but I will drink it if I must. I have every intention of drinking it"  Then, to keep telling yourself this even after they say you won't have to drink it as long as you intend to drink it, and then to keep telling yourself that all the while while they measure your resolve.

In doing this, you should be able to convince both the device and yourself as long as neccesary that this is your intention, until the test is over and then with profound relief you can realize that you are off the hook and with 1 million dollars to boot.