Abstract

This paper examines the criteria that differentiate spontaneous from natural generation in Aristotle’s biological works. It aims to show, first, that what guarantees a natural generation process is the reproductive capacity of living beings of the corresponding kinds. This capacity guarantees the permanence of living beings of the same form in the natural world, for each naturally generating kind and from one generation to the next, as recurrent ends of natural generation processes. The spontaneous formation of living beings due to the coincidence of external heat with suitable material does not display this cyclical structure directed to the reappearance of the same ends , and this feature accounts for their non-teleological character. Second, it is argued that this absence of teleology in kinds of spontaneously generated animals depends on the way their nature and vital heat is the outcome of a chance concoction process of suitable material under right environmental conditions. The relevant passages from the De Generatione Animalium and Meteorologica are interpreted as suggesting that there are such natural chemical processes which allow for the generation of living beings out of non-living matter. Functional explanations may be applicable to the parts of such organisms because their development follows a pattern similar to that of naturally generated organisms. Yet they fall short of displaying the teleological structure apparent in naturally generating kinds