Newcomb’s paradox a conflict between two widely accepted principles of rational decision, arising in the following decision problem, known as Newcomb’s problem. Two boxes are before you. The first contains either $1,000,000 or nothing. The second contains $1,000. You may take the first box alone or both boxes. Someone with uncanny foresight has predicted your choice and fixed the content of the first box according to his prediction. If he has predicted that you will take only the first box, he has put $1,000,000 in that box; and if he has predicted that you will take both boxes, he has left the first box empty. The expected utility of an option is commonly obtained by multiplying the utility of its possible outcomes by their probabilities given the option, and then adding the products. Because the predictor is reliable, the probability that you receive $1,000,000 given that you take only the first box is high, whereas the probability that you receive $1,001,000 given that you take both boxes is low. Accordingly, the expected utility of taking only the first box is greater than the expected utility of taking both boxes. Therefore the principle of maximizing expected utility says to take only the first box. However, the principle of dominance says that if the states determining the outcomes of options are causally independent of the options, and there is one option that is better than the others in each state, then you should adopt it. Since your choice does not causally influence the contents of the first box, and since choosing both boxes yields $1,000 in addition to the contents of the first box whatever they are, the principle says to take both boxes. Newcomb’s paradox is named after its formulator, William Newcomb. Nozick publicized it in ‘Newcomb’s Problem and Two Principles of Choice’ (1969). Many theorists have responded to the paradox by changing the definition of the expected utility of an option so that it is sensitive to the causal influence of the option on the states that determine its outcome, but is insensitive to the evidential bearing of the option on those states. See also DECISION THEORY, UTILITARIAN- IS. P.We.