IdealismIdealism 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 is entirely a mental construct; or that ideas are the highest form of reality or have the greatest claim to being considered "real". The radical latter view is often first credited to the Ancient Greek philosopher Plato as part of a theory now known as Platonic idealism.
RationalismIn philosophy, rationalism is the epistemological view that "regards reason as the chief source and test of knowledge" or "any view appealing to reason as a source of knowledge or justification", often in contrast to other possible sources of knowledge such as faith, tradition, or sensory experience. More formally, rationalism is defined as a methodology or a theory "in which the criterion of truth is not sensory but intellectual and deductive".
MonismMonism attributes oneness or singleness (Greek: μόνος) to a concept, e.g. existence. Various kinds of monism can be distinguished: Priority monism states that all existing things go back to a source that is distinct from them; e.g., in Neoplatonism everything is derived from The One. In this view only the One is ontologically basic or prior to everything else. Existence monism posits that, strictly speaking, there exists only a single thing, the universe, which can only be artificially and arbitrarily divided into many things.
