 This puzzle was originally proposed by William Newcomb but never published. After its first publication by Robert Nozick (1969) it was much discussed within decision theory. But it has also been debated in the context of backward causation, because it gives a nice illustration of some of the philosophical problems that arise in relation to backward causation. In this debate it has been used to demonstrate various claims: that backward causation is impossible or that it implies fatalism or determinism. The earliest discussion of some of the consequences for backward causation and free will can be found in George Schlesinger (1974) and in an exchange between Don Locke (1978, 1979) and André Gallois (1979). Here Schlesinger argued that there are good arguments for taking both boxes, \(A\) and \(B\), and equally good arguments for taking only box B, whereas Locke held that backward causation is irrelevant and the player ought to take both boxes. However, Gallois believed that Locke’s arguments for taking both boxes are misconceived.