 One might wonder what this ‘common life’ is supposed to be, especially in the light of his rejection of Aristotelian ‘substantial forms’. Furthermore, it is tempting to argue that all coherent, solid bodies—such as a lump of rock or plasticene—have some principle of organisation that persists through change. Living objects are simply the most dramatic case of this. (Though Peter van Inwagen (1990) defends the view that only living things and atoms are real entities: inanimate complex bodies are not true individuals.) Nevertheless, though the appeal to ‘life’ seems to modify Locke’s conventionalism, it still leaves open the possibility that the divisions we make between different species are conventions, because, though we can recognise life (or a ‘continuing principle of organisation’) itself, it is still relatively arbitrary and concept-dependent where life (or ‘principle of organisation’) of one kind ends and another starts. So our division of things into species, though grounded in real continuities in the way that our non-biological (or non-natural) concepts are not, is still nominal.