- An impasse. That is what we have. An impasse between so-called three-dimensionalist and so-called four-dimensionalist accounts of persistence. An impasse.
- Despite much vibrant work, especially of late, the leading arguments on each side of this debate seem rather ineffective. Thus, here is my regrettably breezy survey of some influential themes in the literature. The arguments for 3d’ism from the reality of change and from the notion of what it is to be the proper subject of contradictory properties: the 4d’ist has perfectly coherent accounts of these matters, and the argument that these accounts are inadequate is simply question begging. The argument for 3d’ism from the claim that 4d’ism is committed to something like a counterpart theory of modality1 and trans-world identity: this is merely a nice statement of what may be a difference between 3d’ism and 4d’ism; it is not really an argument. If the alleged commitment to counterpart theory is to provide an argument And if you want to have that argument, I would love it. But not now. Fine’s argument for 3d’ism from differences between our ordinary ways of talking and thinking about parts of objects and our ordinary ways of talking and thinking about parts of events: this is a wonderfully subtle argument, sensitive to a range of linguistic and other data. But, as Fine notes, it is open to a 4d’ist to respond by “claiming that our language is deficient and our thought in error.” Indeed, this mass of data seems to tell us simply that the 4d’ist view may go against our intuitions in some respects. But we knew that already. What we need is a way to determine how much weight to give these pro-3d’ist intuitions and a way to measure them against any intuitions or theoretical considerations that may favor 4d’ism. The argument for 4d’ism from the “paradoxes of material constitution”: our intuitions about these paradoxical cases are not strong enough or consistent enough to force a decision either way on the 3d’ism/4d’ism debate or even to make us lean heavily in one direction. Sider’s argument for 4d’ism from vagueness: neat argument, but at most it establishes that objects have temporal parts; as we will see, a 3d’ist can easily accept that claim. Lewis’s argument for 4d’ism from the problem of temporary intrinsics2: it is hard to see how weak or nonexistent intuitions about “just plain having” a property can decide anything of significance in metaphysics.
- In the face of this welter of conflicting and differently weighted intuitions, what is most to be desired is a way to show that the intuitions that drive one theory are somehow internally incoherent or inconsistent. Anything less than this would be opposing one intuition or set of intuitions to another, and that would just continue the trench warfare that has brought us to this impasse. But if it could be shown that one theory is not simply in conflict with its rival but somehow at odds with itself, then — as long as the rival theory is not similarly internally incoherent — we would have at least the beginnings of an effective argument against the incoherent position and thus a way of breaking the impasse.
- The tool that I will employ to try to break the impasse is a new characterization of the difference between 3d’ism and 4d’ism. I will bring to light a claim — namely, that persistence is primitive, inexplicable — which the 3d’ist must, by the very nature of her position, suppose and which the 4d’ist need not suppose. Then — and here is the impasse-breaking move — once we add to the mix a fundamental principle concerning branching and identity to which all, or almost all, the players on either side of the debate are deeply committed, we will be able to see that there is an internal incoherence in the position of all or almost all 3d’ists. This incoherence enables me to mount a new and, I believe, more powerful, less inconclusive argument against 3d’ism and thus for 4d’ism. However, as we will see, the incoherence that threatens 3d’ism also undermines most versions of 4d’ism. What is left at the end of these field-clearing arguments is a version of 4d’ism that rejects all cases of primitive persistence and, more generally, all cases of primitive identity. Thus the view we wind up with is 4d’ism together with the Principle of the Identity of Indiscernibles3 (PII). All other positions on persistence that accept the very popular and plausible principle about branching and identity are, I argue, internally incoherent and should be rejected.
See "Baker (Lynne Rudder) - Three-Dimensionalism Rescued: A Brief Reply to Michael Della Rocca" for a response.
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