Although they are continually compositionally reconstituted and reconfigured, organisms nonetheless persist as ontologically unified beings over time – but in virtue of what? A common answer is: in virtue of their continued possession of the capacity for morphological invariance which persists through, and in spite of, their mereological alteration. While we acknowledge that organisms‟ capacity for the “stability of form” – homeostasis - is an important aspect of their diachronic unity, we argue that this capacity is derived from, and grounded (...) in a more primitive one – namely, the homeodynamic capacity for the “specified variation of form”. In introducing a novel type of causal power – a „structural power‟ – we claim that it is the persistence of their dynamic potential to produce a specified series of structurally adaptive morphologies which grounds organisms‟ privileged status as metaphysically “one over many” over time. (shrink)

This paper evaluates six contenders which might be invoked by essentialists in order to meet Quine’s challenge, viz., to provide necessary and sufficient conditions for the crossworld identity of individuals: (i) an object’s qualitative character; (ii) matter; (iii) origins; (iv) haecceities or primitive non-qualitative thisness properties; (v) “world-indexed properties”; and (iv) individual forms. The first three candidates, I argue, fail to provide conditions that are both necessary and sufficient for the crossworld identity of individuals; the fourth and fifth criteria are (...) open to the charge that they do not succeed in meeting Quine’s demand in an explanatorily adequate fashion. On balance, then, individual forms, or so I propose, deserve to be taken very seriously as a possible response to Quine’s challenge, especially by neo-Aristotelians who are already committed to a hylomorphic conception of composite concrete particular objects for other reasons. Theorists who also accept a non-modal conception of essence, i.e., a conception according to which essence is not reducible to modality, in addition face the further difficult task, over and above what is required to meet Quine’s challenge, of having to explain how an object’s de re modal profile in some way follows from facts about its essence. Haecceities and world-indexed properties, as I indicate, are unlikely to be of much help with respect to this second challenge, while the forms of hylomorphic compounds are in fact well-suited for this purpose. (shrink)