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This paper opposes Universal Mereological Composition. Sider defends it: unless UMC were true, he says, it could be indeterminate how many objects there are in the world. I argue that there is no general connection between how widely composition occurs and how many objects there are in the world. Sider fails to support UMC. Moreover, we should disbelieve in UMC objects. Existing objections against them say that they are radically unlike Aristotelian substances. True, but there is a stronger objection. This is that they are characterized by no properties, and so fail to be like anything—not even themselves.


The final and definitive version of this paper appears in dialectica, 62 (2008), pp. 433-54. This earlier draft of the paper is posted here by the kind permission of dialectica, the European Society for Analytic Philosophy, and Blackwell Publishing. Both this draft and the published version are copyrighted: Copyright 2008, Crawford L. Elder.

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