Mr A. Quinton has attempted to show that the Kantian doctrine of the necessary unity of space rests ultimately on very general contingencies (Philosophy, 1962). More recently, Mr Swinburne has tried to argue the same point for time; and thus he asserts that ‘Kant's unity of time is no more an unalterable necessity of thought than his unity of space’ (Analysis, June, 1965). I wish to defend Kant against both charges, by showing that the charming stories which Quinton and Swinburne tell, in order to show that there are conceivable circumstances in which space and time would not be unitary, do not succeed in showing this at all.