Consider Newcomb’s Problem: “A psychology professor at your school has a reputation for being brilliant as well as possessed of an enormous fortune she has dedicated to her research. One day you get a request to report to her office at a certain hour. On a table are two boxes. One of them, labeled A, is transparent; in it you can see an enormous pile of $100 bills. The other, labeled B, is opaque. She tells you that there is $10,000 in transparent box A and that in box B there is either $1,000,000 or nothing. She tells you that she is going to give you a choice between:"
"1. Taking just what is in box B.
2. Taking what is in both boxes.
(Think about what you would choose given this much information.) Then, she tells you that this is part of an experiment. During registration at the beginning of the quarter, you walked under a peculiar device that reminded you of the machines at airports that are used to prevent hijacking. You didn't think much about it at the time. But, she now informs you that this machine was something she designed and that it recorded an instant profile of your basic personality and character traits. On the basis of your profile, she made a prediction about what choice you would make, and she decided what to put in Box B on the basis of this prediction:
1. If she predicted you would take both, she put nothing in Box B.
2. If she predicted you would take only Box B, she put $1,000,000 in it.
(Now, think about what you would do given this much information.) At this point you ask her how accurate her predictions have been. She says that 1,000 students have been given the choice, and she has only been wrong once. In all the other cases, students who chose both boxes got only $10,000, whereas those who chose only box B got $1,000,000. Then she tells you to choose. What do you do?” —Robert Nozick, “Newcomb's Problem and Two Principles of Choice,” in Essays in Honor of Carl G. Hempel, edited by Nicholas Rescher (Dordrecht, The Netherlands: Reidel, 1970).
For the moment, let’s set aside the question of what you should do and ask what attitudes (e.g., beliefs, desires, intentions, etc.) you should have. First, I think that you should believe that by choosing to take what’s in both boxes you’ll end up with more money than you would by choosing to take only what’s in B. After all, you can see that box A has some money in it. And you have good testimonial evidence that box A contains $10,000. You also have every reason to believe that, by choosing to take what’s in box A, you don’t thereby magically change what’s in box B. So I think that we should accept claim 1:
(C1) You ought to believe that by choosing to take what’s in both boxes you’ll end up with more money than you would by choosing to take only what’s in B.
And so we should also accept claim 2:
(C2) You ought to believe that your choosing to take what’s in both boxes as opposed to your choosing to take only what’s in B is a necessary means to your ending up with more money rather than less money.
Note that C1 and C2 are compatible with both (C3) you ought to believe that if you take what’s in both boxes, you’ll very likely end up with only $10,000 and (C4) you ought to believe that if you take only what’s in box B, you’ll very likely end up with $1,000,000. So even if, like me, you accept both C3 and C4, that should not deter you from accepting C2 as well.
Now, let me just stipulate that the situation is such that you ought to prefer your ending up with more money to your ending up with less money. There might be cases where it would be better if you ended up with less money. But let’s just assume that this is not one of those cases. So we must, given my stipulation, accept claim 5:
(C5) You ought to prefer your ending up with more money to your ending up with less money.
Moreover, it seems that the following is a very plausible normative principle:
(C6) If you ought to prefer E1 to E2 and you ought to believe that your X-ing as opposed to your Y-ing is a necessary means to your getting E1 rather than E2, then you should intend to X and should not intend to Y.
Lastly, it seems to me that we should accept:
(C7) If you should intend to X and should not intend to Y, then you should do X and should not do Y.
So what this all shows, it seems to me, is that those who think that, in Newcomb’s Problem, you should choose only what’s in box B must deny at least one of C2, C6, or C7. For C2, C5, C6, and C7 conjoined entail that you should take what’s in both boxes.
Does rejecting one of these three claims seem like a significant cost to you? And if you are a one-boxer, which of these three would you reject and why? Or do you want to say that this is just a normative dilemma: a case where one cannot perform and have all the acts and attitudes that one should perform and have?