idealism

Idealism is a family of philosophical theories that contend reality is in some fundamental way dependent on minds, ideas, or rational structures. In epistemology it often implies that objects of experience are given through perception and thought, so knowledge is inseparable from the cognitive conditions that make it possible. Some forms hold that the external world exists only as representations within consciousness; others propose that a mind-like reality underlies or constitutes all that is perceived.

Major variants include metaphysical or ontological idealism, which asserts that reality is mental, spiritual, or otherwise non-material in its ultimate nature (as in Berkeley’s immaterialism). Transcendental idealism, associated with Kant, argues that space, time, and causality are the forms imposed by human sensibility, so we never know things-in-themselves—only appearances structured by the mind. Absolute or systematic idealism (associated with Hegel and some British and German thinkers) treats reality as an all-encompassing Mind or Spirit that develops through history and rational reflection. There are also subjective and objective forms that differ in how mind and world relate.

Historically, idealism has influenced metaphysics, epistemology, ethics, and aesthetics, shaping debates over truth, universals, and the status of the external world. It faces challenges from scientific realism and materialism, which emphasize mind-independent explanation and empirical confirmation. In broader use, “idealist” can describe adherence to moral or political ideals guiding action, sometimes contrasted with pragmatic or realist approaches.