Published online by Cambridge University Press: 28 February 2022
According to the relational theory of space-time, the physical world contains spatio-temporal aggregates of matter (spatio-temporally extended physical objects, spatio-temporal parts’ of such objects, and aggregates consisting of spatio-temporal parts of different objects); these aggregates of matter are interrelated in various ways by various geometric (and also non-geometric) relations, but the physical world does not contain a space-time over and above these aggregates of matter and their interrelations.
It is tempting to put this doctrine by saying that there are no space-time regions, but only aggregates of matter. This formulation might be faulted, for a relationalist might want to “logically construct” regions out of aggregates of matter, and given such a “logical construction” the relationalist will assert that regions do exist.
I talked about the topics of this paper in a seminar at MIT in the spring of 1984. I learned a great deal as a result of the sustained discussion by several participants in that seminar, especially Ned Block and Paul Horwich; as a result, this paper includes discussions of many possible strategies for the relationalist that I would otherwise have overlooked. I'd also like to thank Paul Teller for helpful comments on an earlier draft.