  Functionalism is the view that being x is to play the role of x. This paper
defends a functionalist account of three-dimensional entities in the context of
Wave Function Realism (WFR), that can explain in detail how we can recover
three-dimensional entities out of the wavefunction. In particular, the essay
advocates for a novel version of WFR in terms of a functional reductionist
approach in the style of David Lewis. This account entails reduction of the
upper entities to the bottom ones, when the latter behave appropriately. As
applied to WFR, it shows how the wavefunction can turn out to be identical to
three-dimensional objects, provided certain conditions. The first major goal of
the paper is thus to put forward an improved and more rigorous version of WFR,
which dissolves several extant issues about the theory, and can serve as a
starting point for the future literature about the topic. Moreover, the second
major goal of the article is to take WFR as a case study to demonstrate the
pros of functional reductionism, especially in the form defended here, thereby
helping to bring this view back in the philosophy of science debate. The
positive upshots of this paper suggest a possible application of functional
reductionism also to other contexts.
