Key problems of the philosophy of time
The philosophy of space and time is more intimately connected with the nature of psychical theory than any other branch of philosophy. Among the more philosophical questions are :
– whether it is proper to treat space and time as real things (as, in the words of Newton : ‘the places as well of themselves as of all other things’)
– whether it is possible that there should exist empty space and eventless time
– whether our conception of our world as spatially and temporally extended beyond us is a function of an a priori scheme we impose on a reality rather than of reality itself (Kant)
– whether it is proper to think in terms of time flowing, or of the present exietence of past events
– and whether the asymmetry between past and future is logically inviolate or only contingently so.
Among the problems that arise more urgently when we consider physical theory are :
– What is involved by way of observation and what by way of convention when we measure spatial extension and tempral duration ?
– What sense it makes to talk of space as having a given topology or even, as non-euclidean geometry may have it, a finite size ?
– What are the implications of the two theories of relativity for the relationship between space and time ?
Absolute vs relational theories
The main opposition is betwwen champions of absolute and relational theories.
An aboslutist takes Newton’s metaphor of the container seriously. He regards space and time as real things, containers of infinite extension or duration within the whole succeesion of natural events in the world has a definite position. Similarly, things may really be at rest or really moving, and this will not simply be a matter of their relationship to other objects changing. The first thoroughgoing relationist opposition to this came from Leibniz: in his metaphysics absolute space vanishes, partly because reality is not spatial at all. Similarly in Kant the interpretation of our experience as that of a spatially extended world is an act of the mind: things-in-themselves have no spatial properties. less strenguous relationists try to preserve the reality of space or time by interpreting propositions about them as asserting nothing but relations among ordinary material things: the container is not logically distinct from the things ot is said to contain. The obvious obstacle here is that the relations involved are sui generis – spatial and temporal – so that the gain is unclear. One intriguing focus for this dispute is Kant’s problem of the incongruous counterparts: if we imagine a universe containing just one hand and nothing else it must be either a left hand or a right hand even although all the relations of things, for example, of the palm to the index finger, would be the same in either case.