Abstract Some plausibly necessary a posteriori theoretical claims include ‘water is H 2 O’, ‘gold the element with atomic number 79’, and ‘cats are animals’. In this paper I challenge necessity of third claim. argue that there possible worlds in which cats exist, but not animals. Under any species concepts currently accepted biology, organisms do belong essentially to their species. This equall...

DATA TYPE See DATA ABSTRACTION ABSTRACTION (The result of) a process of simplification, to describe something at a more general level than the level of detail seen from another point of view. This is often achieved by omitting details specific to individual cases or to methods of implementation. For example, a realtor’s description of a house may leave out architectural detail so that it is an ...