Idealism is a family of metaphysical views each of which gives priority to the mental. The best-known forms of idealism in Western philosophy are the versions developed by George Berkeley and Immanuel Kant. Although idealism was once a dominant view in Western philosophy, it has suffered almost total neglect over the last several decades. The contemporary debate has focused almost exclusively on physicalism and dualism, though the alternative views of panpsychism and neutral monism are beginning to receive more attention. This book remedies the situation by bringing together seventeen new essays by leading philosophers on idealism. They explain, attack, or defend a variety of forms of idealism—not only Berkeleyan and Kantian versions, but also Buddhist and Jewish versions, and others besides. The essays are all contributions to metaphysics, but variously focus on philosophy of mind, philosophy of religion, philosophy of mathematics, philosophy of science, philosophy of language, and other areas of philosophy.

Idealism in philosophy, also known as philosophical idealism or metaphysical idealism, is the set of metaphysical perspectives asserting that, most fundamentally Idealism in philosophy, also known as philosophical idealism or metaphysical idealism, is the set of metaphysical perspectives asserting that, most fundamentally, reality is equivalent to mind, spirit, or consciousness; that reality or truth is entirely a mental construct; or that ideas are the highest type of reality or have the greatest claim to being considered "real". Because there are differe Today, idealism remains a minority view in Western analytic circles. In spite of this, the study of the work of the Anglo-American idealists saw a revival in the 21st century with an increase in publications at the turn of the century, and they are now considered to have made important contributions to philosophy. Several modern figures continue to defend idealism. Recent idealist philosophers include A. A. Luce (Sense without Matter, 1954), Timothy Sprigge (The Vindication of Absolute Idealism, 1984), Leslie Armour, Vittorio Hösle (Objective Idealism, 1998), John Andrew Foster (A World for Us, 2008), John A. Leslie (Infinite Minds: A Philosophical Cosmology, 2002), and Bernardo Kastrup (The Idea of the World, 2018). In 2022, Howard Robinson authored Perception and Idealism. Both Foster and Sprigge defend idealism through an epistemic argument for the unity of the act of perception with its object. Sprigge also made an argument from grounding, which held that our phenomenal objects presuppose some noumenal ground. As such For Sprigge, the physical world "consists in innumerable mutually interacting centres of experience, or, what comes to the same, of pulses and flows of experience." Thus, the noumenal ground is the totality of all experiences, which are one "concrete universal", that resembles Bradley's absolute. Helen Yetter-Chappell has defended nontheistic (quasi-)Berkeleyan idealism.

Idealism is now usually understood in philosophy as the view that mind is the most basic reality and that the physical world exists only as an appearance to or expression of mind, or as somehow mental in its inner essence. However, a philosophy which makes the physical world dependent upon mind is usually also called idealist even if it postulates some further hidden, more basic reality behind the mental and physical scenes (for example, Kant’s things-in-themselves). There is also a certain tendency to restrict the term ‘idealism’ to systems for which what is basic is mind of a somewhat lofty nature, so that ‘spiritual values’ are the ultimate shapers of reality. (An older and broader use counts as idealist any view for which the physical world is somehow unreal compared with some more ultimate, not necessarily mental, reality conceived as the source of value, for example Platonic forms.) The founding fathers of idealism in Western thought are Berkeley (theistic idealism), Kant (transcendental idealism) and Hegel (absolute idealism). Although the precise sense in which Hegel was an idealist is problematic, his influence on subsequent absolute or monistic idealism was enormous. In the US and the UK idealism, especially of the absolute kind, was the dominating philosophy of the late nineteenth and early twentieth century, receiving its most forceful expression with F.H. Bradley. It declined, without dying, under the influence of G.E. Moore and Bertrand Russell, and later of the logical positivists. Not a few philosophers believe, however, that it has a future.