  There has been much dispute about whether General Relativity supports relationism or substantivalism about spacetime. The main problem for the latter is the general covariance of the field equations of General Relativity: any spacetime model and its image under a diffeomorphism (a infinitely differentiable, one-one and onto mapping of the model to itself) are in all observable respects equivalent to one another; all physical properties are expressed in terms of generally covariant relationships between geometrical objects. In other words, since the points of spacetime are entirely indiscernible one from another, it makes no difference if we swap their properties around so long as the overall structure remains the same. This is made more apparent by the so-called ‘hole argument’ which shows that if diffeomorphic models are regarded as physically distinct then there is a breakdown of determinism. Substantivalists cannot just bite the bullet and accept this since, as John Earman and John Norton (1987) argue, the question of determinism ought to be settled on empirical/physical grounds and not a priori ones.