Abstract

In his biological works Aristotle frequently applies the language of abnormality to those individual members of natural kinds which fail through various defects to live up to the standard of their kind. Aristotle extends this language of abnormality to natural kinds themselves, and will often speak of kinds as‘ deformed’ or ‘warped’.1 In the vast majority of his references to abnormal kinds,2 Aristotle represents them as defective only because they do not measure up to some standard of excellence, and not because of any genuine distortion of their nature. In one category of cases the defective species belongs to a genus which demands a certain characteristic of its species, but which the defective species does not possess. The lobster, for example, belongs to a genus that possesses claws for prehension and for defence, and thus it too possesses claws. It is, however, ‘deformed’, because it does not use its claws in the natural way, but rather for locomotion. Such deformities as these may even conform to Aristotle′s teleology and promote the good of the defective species. The seal, for example, belongs to the genus, the viviparous terrestrial, which requires external ears of its members. The seal does not possess them, and consequently is ‘deformed’. Yet Aristotle also argues that the seal′s lack of external ears is an advantage, because of its aquatic life, and Nature acts ‘reasonably’ in depriving it of them. In another category of cases the abnormal kind is defective with respect to a broader standard of excellence that lies outside its genus. Testaceans, such as the snail, are ‘deformed’ because they move ‘contrary to nature’. They do not move like a footed animal, but as if they were footed animals whose legs have been cut off. This category of abnormality even takes in the whole of the animal kingdom, with the exception of man. For every animal is ‘dwarf-like’ in comparison with man, which is the best of animals, because the upper part of every animal′s body, in contrast with that of man′s, is larger than its lower part.