- This chapter attempts to provide a general framework for discussing the plausibility of various so-called causal theories of spacetime. Two distinct classes of such theories are delimited. In the first class are those attempts at reducing spatiotemporal to causal structure which rely upon an allegation that our full epistemic access into spacetime structure is through direct epistemic access to a limited class of relationships among events. The second class of theories are those which allege that spatiotemporal structure is reducible to causal structure in a manner more like that in which one level of entities and properties in the world is shown to be identical to some other level of entities and properties by means of a scientific reduction proceeding through an identification. In both cases pushing the allegation of causal reduction to its limits results in philosophical perplexity.
- Examples of the first kind of reduction are the so-called causal theories of the metric of Minkowski spacetime (as in Robb), and causal theories of spacetime topology in general relativity. In these cases there is first an initial problem of guaranteeing that the causal structure invoked is sufficient to extensionally fix the spacetime structure in question in any model of the world allowed by the theory in question. Even after this problem has been resolved, there are deep philosophical difficulties in justifying the epistemic foundational claims needed to motivate the reductionist program. Finally, there is the tendency of such programs, endemic to epistemically motivated reductionist programs, to push us into unacceptably solipsistic views of the world.
- Examples of the identificatory reductive programs are then sketched. Here again there are certain fundamental philosophical obstacles to rationalizing the reductions. Finally, pushing the claims of such identificatory reductions to their limits tends, in a familiar manner, to separate off the world of experience from the world hypothesized by our natural science, in a manner which may leave us perplexed when such fundamental features of the world as its spatiotemporality, as we experience it, are reduced to mere "secondary qualities."
- Some of the material discussed here has been treated at greater length in chapter 31 and in chapter 92.
Originally, R. Swinburne (ed.), Space, Time, and Causality3, Dordrecht: Reidel, 1983, 45-62.
Footnote 1: See "Sklar (Lawrence) - Facts, Conventions, and Assumptions in the Theory of Spacetime".
Footnote 2: See "Sklar (Lawrence) - What Might Be Right about the Causal Theory of Time".
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