Natural Kinds: (Thick) Essentialism or Promiscuous Realism?

Theoretical identity statements of the form "water is H2O‟ are allegedly necessary truths knowable a posteriori, and assert that nothing could be water and not be H2O. The necessary a posteriori nature of these identity claims has been taken by Kripke, Putnam and Donnellan to justify a move from talk of reference (language) to talk of essence (metaphysics), and has motivated much of contemporary essentialism. In this paper I will contest this move from reference to essence, and argue that (i.) the only way to derive essentialism from semantics (specifically direct reference) is to assume it as a premise, (ii.) that contemporary essentialism is a metaphysical assumption not a thesis, and (iii.) – assuming the accuracy of the analogy between proper names and natural kind terms – present an alternative version of natural kinds classification that is interest-relative, dependent on practical application and reflects the contingent state of affairs which is our world.