Abstract

Advances in molecular biology have generally been taken to support the claim that biology is reducible to chemistry. I argue against that claim by looking in detail at a number of central results from molecular biology and showing that none of them supports reduction because (1) their basic predicates have multiple realizations, (2) their chemical realization is context-sensitive and (3) their explanations often presuppose biological facts rather than eliminate them. I then consider the heuristic and confirmational implications of irreducibility and argue that purely biochemical approaches are likely to be unsound and to be unable to confirm an important range of statements. I conclude by sketching criteria for scientific unity that do not entail reducibility and yet leave an important place for identifying underlying mechanisms. Molecular biology, properly understood, provides an excellent paradigm of non-reductive unity between different explanatory levels