ABSTRACT
The question that has dominated discussion of space and time in the philosophy of science concerns their ontological status. Newton, famously, claimed that space was an entity in its own right (1999 [1687]: 408). His substantivalist position was lambasted by Leibniz, who argued for the relationalist view that space is nothing “besides the order of bodies among themselves” (Leibniz 1956 [1716]: 26). Both views attracted adherents in the two centuries that followed, before the context was radically transformed by Einstein’s theories of relativity. In the first half of the twentieth century, philosophical consensus judged that general relativity vindicated Leibniz’s relationalism (Reichenbach 1959). With the demise of logical empiricism, opinion changed. Newton was portrayed as making a respectable inference to the best explanation, from inertial effects to the existence of absolute motion and thus to absolute space. This inference (suitably modified) was thought to remain legitimate in general relativity. Recent historical and philosophical work reveals this to be a badly misleading caricature of Newton’s arguments (Rynasiewicz 1995). But arguably this recent scholarship casts Newton, and his realism about spacetime structure, in even better light. Another question concerns the explanatory role of space and time. The idea that Newton advanced an inference from inertial effects to the existence of space suggests a picture in which space exerts something like a causal influence on its material contents. Some think that this gets the order of explanation exactly the wrong way round: it is not that, for example, rods and clocks are constrained to behave as they do by the geometric structure of the spacetime in which they are immersed. Rather, goes the claim, it is the correlated lawlike behavior of rods and clocks that underwrites spacetime’s geometric structure. Two important topics are not discussed further below. The first is conventionalism: to what extent is our attribution of a particular geometry to physical space and time a stipulative convention? The second is the so-called “arrow of time” and in particular how the time asymmetry of thermodynamics is related to supposedly time-symmetric fundamental physics. Those interested in pursuing these topics are referred to the suggestions for further reading at the end of this chapter.
