Any theory emphasizing the existence, priority, or value of matter or material objects; though the popular sense of emphasizing the value of material things is uncommon in philosophy.
Usually materialists say that matter alone exists, everything else (notably minds or spirits and their ideas and experiences) being analyzable in terms of matter (a form of reductionism; also see: identity theory of mind); or else, more weakly, that though minds and so on may be different from matter, they originated from matter and would not exist without it (a form of emergence theory).
A slightly less weak materialism would add that such minds would vanish were matter to vanish (since they still depend on it causally). For a still weaker version see immaterialism. Materialists may also deny the substantive and irreducible existence of abstract objects like properties, numbers, propositions, and so on though this is usually less emphasized.
Modern physics has cast the notion of matter itself into some confusion, though in ways that have not so far greatly affected the above debates; problems concerning it, and in particular its relation to space, go back at least to Rene Descartes (1596-1650) and indeed to Plato (4th century BC).
Also see: dialectic
A Quinton, The Nature of Things (1973)