What if mind, not matter, is the bedrock of everything?
Idealists argue that reality is at bottom mental: spirit, consciousness or ideas come first, and physical things depend on them. The claim sounds exotic, yet it has champions from Vedanta and Yogacara Buddhism to Plato, Berkeley, Kant and Hegel, and some modern versions even imagine quarks and photons as tiny conscious subjects.
The word descends through Latin from the Greek idein, to see. It reached English by 1743, and Christian Wolff first gave it the abstract sense of reality made only of ideas in 1747. Because so many positions shelter under the label, a single tidy definition has proved elusive. Willem deVries offers a rough one: theories that grant the mental priority over the non-mental, which rules out both materialism and dualism.
A key split separates two kinds of argument. Ontological idealism says reality itself is mental or grounded in something mental, making it a form of monism; George Berkeley's immaterialism is the classic Western case, joined by Hegel and F. H. Bradley. Epistemological idealism makes a humbler claim, that everything we know comes filtered through mental structures, whatever lies beyond them. Its main Western source is Kant's transcendental idealism, which refuses to say whether the thing in itself is mental. A. C. Ewing suggested speaking of arguments for idealism rather than two species of it.
Within the ontological camp there is plenty of disagreement. Leibniz's monadology is pluralist, positing many independent minds, while absolute idealism, found in Hegelianism and in Advaita Vedanta, sees a single unified reality. Subjective idealists like Berkeley deny a mind-independent world; objective idealists accept a world beyond experience but deny it is cut off from consciousness. David Chalmers sorts views by scale, distinguishing micro-idealism rooted in fundamental particles, macro-idealism rooted in creatures such as humans, and cosmic idealism rooted in the universe or a deity.
Ancient precursors are debated. Anaxagoras taught that nous, mind, set everything in motion, and Hegel read Parmenides as an idealist for equating thinking with being. Plato placed timeless forms above the changing world, yet still counted perceived matter as real, so some scholars call him a dualist. Plotinus, by contrast, is credited by several historians with the first Western idealism holding that only mind exists. In the twentieth century G. E. Moore and Bertrand Russell led an analytic attack, alongside new realists and Marxists.
Source: Idealism
