Substance, Relations, and Arguments about the Nature of Space-Time

Abstract

Newton and Leibniz debated the nature of space: Is it a substance, a collection of particulars (points, or regions), existing independently, and providing an objective framework of spatial reference (substantivalism)? Or should we say that substantival space is an illusion, there being nothing more than the spatial relations holding between physical objects or events (relationalism)? Today the terms of the debate have changed, since relativity theories show that space and time must be treated together. So we now ask the same question about space-time points: Should we take at face value conventional presentations of relativity theories which describe phenomena in terms of a manifold, a collection of objectively existing space-time points? Or should we try to reinterpret these descriptions, saying that all that really exists are the space-time relations which hold between objects or events? With the question asked in terms of space-time points we have the old opposition in a new form. And, likewise, we continue to debate the two main lines of for these two viewsLeibniz's indiscernibility argument and Newton's bucket argument. I believe that in their traditional form neither of these intuitively compelling arguments has nearly the strength that many have seen in them. Examining these arguments will lead to exam