Crisp Islands in Vague Seas: Cases of Determinate Parthood Relations in Biological Objects

Abstract

Biological entities are embedded in cascades of mereological systems, both on the level of individuals and on the level of classes. But there are, in fact, numerous borderline cases, in which biological parthood is vague or otherwise indeterminate. In this paper, we distinguish between two kinds of criteria for biological parthood: We argue that criteria based on spatial inclusion, function, origin and genetic identity are useful rules of thumb, but do allow for exceptions, even when taken in combination. Hard criteria, which do not admit exceptions, can be found when we refer to linguistic or ontological necessities. We find such necessities in collections, compounds, fiat partitions, and immaterial entities, which allow formulating some general axioms for biological parthood. To be sure, these are islands of crispness in seas of vagueness.