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Andrea Bottani pmsstud@tin.it University of Genoa and Fribourg  Lewis and Lowe on Temporary Intrinsics and Material Objects According to some philosophers, the only way material objects can persist through change is by having temporal parts: just as processes or events, persisting things are four-dimensional entities extending through time as well as in space. According to other philosophers, material things differ from processes in having spatial but not temporal parts: they are three-dimensional entities which persist through time without extending through time (if a material object exists at a number of times, then it is - so to say - wholly present at each of them). An important difference between the two views is that according to the former there is no genuine relation of identity through time (but only, at most, some substitute of it such as Reichenbach's 'genidentity' or Perry's 'unity relation'), whilst according to the latter identity through time is just as genuine as identity at a time. Another difference is that, according to the first view, a continuant is just the mereological sum of its (temporal) parts whilst, according to the latter, no continuant can be identified with a mereological sum or aggregate (mereological extensionality holds for mereological aggregates but not for continuants, for they can gain and loose parts along their life history). In The Plurality of Words, Lewis named the two views respectively perdurance theory and endurance theory of continuants and defended the former by an argument hinged on what he called the problem of 'temporary intrinsics'. Oversimplifying, the argument runs as follows. Continuants change not only in their relationships with other things but also in their intrinsic properties. For example, I change my shape: when I sit I am bent, when I stand I am straight. So, I have intrinsic properties that are merely temporary, i.e. I do not have them along my whole life history. But how can I both have and fail to have the same intrinsic property (for example a certain shape) without changing my very identity? One could answer that shapes are not genuine intrinsic properties of a continuant but disguised relations it bears to times: 'the whole of me stand in the bent-at relation to some times and in the straight-at relation to others'. This is the view that continuants endure and is untenable, because it denies that shapes are intrinsic properties of things: nothing, from this point of view, can have a shape simpliciter. The only viable alternative is to maintain that incoherent temporary intrinsics do not belong to the same thing. I am a sum of temporal stages with different intrinsic properties: "when I sit and then stand, bent stages are followed by straight stages". This is the view that continuants perdure and is the only way of accommodating the existence of temporary intrinsic properties. Lowe denies that Lewis's solution is tenable. As he finds unintelligible the notion of a temporal stage of a continuant, he believes that Lewis's solution "has all the hallmarks of the sort of pseudo-explanation that used to give philosophy a bad name". On the other side - Lowe remarks - we have no need of perdurance, for it is modern physics itself to give us an easy solution of the problem of temporary intrinsics. Physics tells us that bodies consist of particles. So, when I change my intrinsic shape, what really happens is that my particles change their extrinsic relations. Temporary intrinsic properties of macroscopic continuants are simply temporary extrinsic relations of their particles. According to Lowe, this fits common sense fairly well. On the other side, physics tells us that elementary particles never change their intrinsic properties (such as charge, rest mass etc.). So, the problem of temporary intrinsics totally vanishes. According to Lewis, change of intrinsic properties as rearrangement of particles is hardly convincing. First, it may turn out that elementary particles do after all change their intrinsic properties. Second, a world where particles fluctuate in their intrinsic charges is logically possible: how could us make sense of counterfactual suppositions about continuants in such a world? Third, Lowe does not settle the problem of intrinsic temporary relations: how can the same two particles stand and fail to stand in the same intrinsic relation without changing their identity? Fourth, what about ordinary macroscopic continuants? As they change their particles, they cannot be identical with any sum of particles. What can they be identical with, then, if sums of temporal stages are unintelligible? Lowe ends by giving no answer. Lewis's attack on Lowe's solution seems to me far to be conclusive. The first criticism shows that Lowe's view is not more certain than modern physics, but fails to show that it is false. The second criticism shows that Lowe's view is not more logically true than modern physics, but fails to show that it is false. The third criticism admits a reply sketched by Lewis himself. The fourth criticism, finally, is simply mistaken: Lowe can answer the question what a macroscopic continuant is identical with. The natural answer from his point of view is that a macroscopic continuant such as a table, a tree or a town is identical with nothing physical, for it does not exist physically: it is a mere manner of speaking or a logical construction, in the sense worked out in Chisholm's theory of entia successiva. Lowe's solution is merely the application of a Chisholm style mereology to the problem of temporary intrinsics. It has all the main features of Chisholm's approach, in primis the adoption of the principle of mereological extensionality and the rejection of the notion of a temporal part. To be sure, this kind of reductionist ontological approach complicates the account of the truth conditions of sentences concerning entia successiva (tables, trees or towns), but it is not obvious that these difficulties are so big as to compromise the approach itself. Finally, what about Lewis's attack on the view that ordinary material continuants endure? The friends of endurance, Lewis says, have to treat the shape of a continuant not as a genuine intrinsic property of it but as a disguised relation it bears to times. But it is not in the same way (i.e. as a disguised relation) that a friend of perdurance ends by treating the shape of a continuant? Actually, as Lewis remarks, what distinguishes one view from the other is not that the latter 'does away with shape-at-a-time relations. Rather, it is that [according to the first] nothing just has a shape simpliciter'. This looks plainly false: according to the first view, everything that has permanently a shape (for example, a topo-chronologically individuated entity) has a shape simpliciter (even if it is a temporal part of nothing). Then, what is Lewis's point about perdurance versus endurance? According to both views, there are intrinsic and extrinsic properties. According to both views, shapes are sometimes intrinsic and sometimes extrinsic, sometimes temporary and sometimes permanent (depending on what they are shapes of). But, according to both views, shapes are never intrinsic-and-temporary properties, for surely there is no such property. |
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