Two boxes A and B are before you. You know that box A contains $1,000 whereas box B contains either a million dollars or nothing, though you don’t know which. You may take both boxes or just box B, where you will get whatever money is contained in the box or boxes you take. However, a man has predicted in advance (e.g., yesterday) which choice you would make and has left the million dollars in box B if he predicted that you would take just box B, as opposed to nothing in box B if he predicted that you would take both boxes. You have reason to believe that this man is very likely to have predicted your choice correctly, e.g., he has an excellent track record of such predictions. If your only aim is to get as much money as you can, should you take take both boxes or just box B?This is Newcomb’s problem and it is a problem because, given the facts described, there is a very compelling argument for taking both boxes but an equally compelling argument for taking just box B. Again, I assume that these arguments are well-known—though more on this below.
We never were given any choice about whether to have a million. When we made our choices, there were no millions to be had. (Lewis 1981, p. 377.)These words are a godsend for my purposes because they encapsulate in a pithy way the essential error I have been labouring to expose: from the mere fact that no millions were to be had, it does not follow that you were never given any choice about whether to have a million.
That this remark was made some thirty years after Newcomb’s problem first surfaced is quite remarkable. Nevertheless, this essay is my response. There is something that “with plausibility” can be said against the case for taking both boxes and I have tried to say it above. It has satisfied me from the moment it struck me and I have never lost a night’s sleep over Newcomb’s problem since then. Wittgenstein once said that while scratching an itch may be a sort of philosophical progress, what one really wants is to be rid of the itch altogether. This answer did it for me and I recommend it to any one-boxer who has yet to overcome his or her conscience. If you remain an unmoved two-boxer, however, I doubt that anything I say could ever move you. I recommend instead a short stint as top chef in the kitchen galley of a major airline!One-boxers of course reject the dominance argument for two-boxing, but they never say what they find wrong with it other than its conclusion. They never explain how, in their views, well-meaning two-boxers are taken in by their arguments … One explanation for it would be that there is nothing wrong with the plain and simple causal-dominance argument for two-boxing, and that there is nothing with plausibility that can be said against it. (Sobel 1998, p. 68.)