- If the property being a methane molecule is a universal, then it is a structural universal: objects instantiate being a methane molecule just in case they have the right sorts of proper parts arranged in the right sort of way. Lewis argued (in "Lewis (David) - Against Structural Universals") that there can be no satisfactory account of structural universals1; in this paper I provide a satisfactory account.
- This is a pre-print of an article whose final and definitive form (was) published in the Australasian Journal of Philosophy in 2009.
- Lewis’s Challenge
- Three conceptions of structural universals2
… 3.1 The Linguistic Conception
… 3.2 The Pictorial Conception
… 3.3 The Magical Conception
- A fourth conception of structural universals3
- Uniqueness and the Composition-Identity Analogy
- Residual Magic?
- Modal Reductionism
- Conclusion: I have not argued that universals4 exist. There are a number of theoretical roles which could be filled by universals5, but there are rival candidates for those positions. Nor have I argued that, if there are universals6, then there are structural universals7: Lewis provided some arguments for this conditional claim, though the strongest has recently been under attack [Williams 20078]. Nevertheless I have tried to clarify the structure of Lewis’s argument against structural universals9, highlighting its dependence both upon Leibniz’s Law as the ultimate brute necessity, and upon the claim that composition must be unique if it is to avoid unacceptable brute necessities. I have undermined this second claim, I have shown what can reasonably be expected of a theory of structural universals10, and, finally, I have shown that any theory with the resources to provide an account of possible worlds will have to take mereological essentialism (or its equivalent) for universals11 as brute.
Footnote 8: Williams, R. 2007. The Possibility of Onion Worlds: Rebutting an Argument for Structural Universals, Australasian Journal of Philosophy 85: 193-203
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