It is widely acknowledged that metaphysical assumptions, commitments and presuppositions play an important role in science. Yet according to the empiricist there is no place for metaphysics as traditionally understood in the scientific enterprise. In this paper I aim to take a first step towards reconciling these seemingly irreconcilable claims. In the first part of the paper I outline a conception of metaphysics and its relation to science that should be congenial to empiricists, motivated by van Fraassen’s work on ‘stances’. (...) There has been a considerable amount of recent work devoted to van Fraassen’s ‘stance’ view, but it has not on the whole been noticed that the view has the potential to motivate a general empiricist conception of the relation between science and metaphysics. In the second and third sections I discuss two examples from biology to illustrate this conception: metaphysical punctuationism, and its relation to and influence on the thesis of punctuated equilibrium; and dialectical biology as defended by Levins and Lewontin. (shrink)