Monism is a metaphysical position that explains reality in terms of a single fundamental kind of being or underlying principle. Different forms of monism identify that basic reality in different ways. Materialist monism treats physical matter as fundamental, while idealist monism treats mind or consciousness as primary. Other forms propose a neutral or more basic substance underlying both mental and physical phenomena. Monism is often contrasted with dualism and is closely connected with debates about the Mind-Body Problem, substance, matter, consciousness, materialism, and idealism.