 Consequently, Cohen claims that we can be justified in offering a functional explanation even when we are in ignorance of its elaboration. Indeed, even in biology detailed causal elaborations of functional explanations have been available only relatively recently. Prior to Charles Darwin (1809–1882), or arguably Jean-Baptiste Lamarck (1744–1829), the only candidate causal elaboration was to appeal to God’s purposes. Darwin outlined a very plausible mechanism, but having no genetic theory was not able to elaborate it into a detailed account. Our knowledge remains incomplete in some respects to this day. Nevertheless, it seems perfectly reasonable to say that birds have hollow bones in order to facilitate flight. Cohen’s point is that the weight of evidence that organisms are adapted to their environment would permit even a pre-Darwinian atheist to assert this functional explanation with justification. Hence one can be justified in offering a functional explanation even in the absence of a candidate elaboration: if there is sufficient weight of inductive evidence.