Science, philosophy of

3. Contemporary philosophy of science: ‘scientific metaphysics’

Suppose that we take a vaguely realist view of current science, what does it tell us about the general structure of reality? Does a sensible interpretation of science require the postulation, for example, of natural kinds (see Natural kinds) or universals? Does it require the postulation of a notion of physical necessity to distinguish natural laws from ‘mere’ regularities (see Laws, natural)? What is the nature of probability (see Probability, interpretations of) – is a probabilistic claim invariably an expression of (partial) ignorance or are there real, irreducible ‘objective chances’ in the world? What exactly is involved in the claim that a particular theory (or a particular system described by such a theory) is deterministic (see Determinism and indeterminism), and what would it mean for the world as a whole to be deterministic? Does even ‘deterministic’ science eschew the notion of cause (as Russell argued)? Does this notion come into its own in more ‘mundane’ contexts, involving what might be called ‘causal factors’ and probabilistic causation? What exactly is the relationship between causal claims – such as ‘smoking causes heart disease’ – and statistical data (see Causation)? How should spacetime be interpreted (see Spacetime): as substantive or as ‘merely’ relational? Does current science plus whatever ideas of causality are associated with it unambiguously rule out the possibility of time travel (see Time travel), or does this remain at least logically possible given current science?

Finally, and most generally, what is science (or, perhaps more significantly, the direction of scientific development) telling us about the overall structure of the universe – that it is one simple system governed at the fundamental level by one unified set of general laws, or rather that it is a ‘patchwork’ of interconnected but separate, mutually irreducible principles (see Unity of science; Reduction, problems of)? Although it is of course true – despite some exaggerated claims on behalf of ‘theories of everything’ – that science is very far from reducing everything to a common fundamental basis, and although it is of course true that, even in cases where reduction is generally agreed to have been achieved, such as that of chemistry to physics, the reduction is ontological (that is, chemistry has been shown to need no essential, non-physical primitive notions) rather than epistemological (no one would dream of trying actually to derive a full description of any chemical reaction from the principles of quantum mechanics), some would nonetheless still argue that the overall tendency of science is in the reductionist direction (see Chemistry, philosophical aspects of §5).

These are examples of the more or less general, and impressively varied, ‘metaphysical’ issues informed by science that have attracted recent philosophical attention.