I examine the debate between reductive and non-reductive physicalists, and conclude that if we are to be physicalists, then we should be reductive physicalists. I assess how both reductionists and non-reductionists try to solve the mind-body problem and the problem of mental causation. I focus on the problem of mental causation as it is supposed to be faced by non-reductionism: the so-called overdetermination problem. I argue that the traditional articulation of that problem is significantly flawed, and I show how to (...) articulate it properly: what I call the ‘super-overdetermination problem’. In doing so, I demonstrate that the problem of mental causation faced by non-reductionism is in fact a special case of the mind-body problem, as faced by non-reductionism, and that the former can’t be solved independently of the latter. I then assess the prospects for a particular family of non-reductive views that I call immanentism, and show that they fail to solve the super-overdetermination problem. Finally, I put forward two arguments to support the conclusion that physicalism entails reductionism. Both arguments establish, via distinct reasoning, the proposition that mental property instances are identical to physical property instances; and then each argument employs the inference, which I also defend, that if mental instances are physical instances, then mental properties are physical properties; hence, reductionism follows. (shrink)