[To appear in Peter Anstey (Ed.), The Oxford Handbook of British Philosophy in the Seventeenth Century]
The problem of generation, at its broadest, concerns the way in which entities that at one time do not exist, later do. The generation of animals is just one instance of this problem, as are the coming-into-being of minerals, plants, mountains and other features of the natural environment; planets, stars, and the cosmos itself. In any given domain, there are, to put it succinctly, three possible solutions to the problem: (i) to hold that nothing ever really comes into being, but only emerges out of a new arrangement of preexisting material parts; (ii) to hold that nothing ever really comes into being, but is always itself pre-contained in the world in a hidden form; (iii) to hold that new creatures come into being as a result of the imposition of some new form on matter, either as a result of God’s direct intervention (as in the traditional Christian account of human embryogenesis) or of the transition of a previously merely potential form to actuality. One might adopt one of these solutions for a given domain, and another for another: for example, one might hold that the generation of humans involves the supernatural creation of a soul by God in, say, the fourth month of gestation, while in contrast the ‘generation’ of a mountain is really just the rearrangement of already existing dirt. But in general for those entities to which natural philosophers have traditionally wanted to ascribe some substantial reality, or reality over and above the parts that compose them, only the second or third solution would do.
Thus, we may see the problem of generation as consisting in the set of fundamental questions: What things are such that their being cannot be accounted for in terms of the mere rearrangement of things in the world? If their being is not due to such rearrangement, then how can we account for the fact that they do not appear to have always existed? Have they in fact always existed, but in a manner unknown to us? And how could the other option --that they are supernaturally created at a given moment-- be tenable if one is committed to the view, as so many 17th-century British philosophers were, that everything in the world unfolds according to rigid mechanical laws? In this chapter, we will follow what appears to have been the convention in most natural-philosophical writing of the early modern period, in treating questions of 'biological' generation interchangeably with those coming from chemistry, mineralogy, meteorology, etc. How do actually existing things come into being? That is the question, whether it concerns humans, frogs, chemical compounds, or comets.