 Cohen is well aware of the difficulty of appealing to purposes in history, but defends the use of functional explanation by comparing its use in historical materialism with its use in evolutionary biology. In contemporary biology it is commonplace to explain the existence of the stripes of a tiger, or the hollow bones of a bird, by pointing to the function of these features. Here we have apparent purposes which are not the purposes of anyone. The obvious counter, however, is that in evolutionary biology we can provide a causal story to underpin these functional explanations; a story involving chance variation and survival of the fittest. Therefore these functional explanations are sustained by a complex causal feedback loop in which dysfunctional elements tend to be filtered out in competition with better functioning elements. Cohen calls such background accounts “elaborations” and he concedes that functional explanations are in need of elaborations. But he points out that standard causal explanations are equally in need of elaborations. We might, for example, be satisfied with the explanation that the vase broke because it was dropped on the floor, but a great deal of further information is needed to explain why this explanation works.