This article aims to deal with the problem of function pluralism in biology. The debate on function pluralism involves two conflicting sides: between-discipline pluralism and within-discipline pluralism. The majority of philosophers of biology are between-discipline pluralists. According to them, different theories of biological function – the selected effects theory and the causal role theory – are appropriate to different branches of biology; the selected effects theory is the most appropriate theory for evolutionary biology, while the causal role theory is the most appropriate theory for physiology – e.g., anatomy, neuroscience, and developmental genetics. On the contrary, within-discipline pluralism holds that we should seek out a plurality of functions inside any branch of biology. More precisely, according to within-discipline pluralists, selected effects functions and causal role functions can coexist within the same field. In this paper, I will introduce arguments both in favour and against between-discipline pluralism. Afterwards, I will exhibit how the arguments provided against between-discipline pluralism motivate within-discipline pluralism. Finally, I will develop an argument that may be of help to prove the case of within-discipline pluralism.
