“realism: In philosophy, any viewpoint that accords to the objects of human’s knowledge an existence that is independent of whether they are perceiving or thinking about them. Against nominalism, which denies that universals have any reality at all (except as words), and conceptualism, which grants universals reality only as concepts within the mind, realism asserts that universals exist independently of their being expressed in language and conceived by human minds. Against idealism and phenomenalism, it asserts that the existence of material objects and their qualities is independent of their being perceived. Similarly, moral realism asserts that moral qualities of actions (such as being morally good, bad, or indifferent, or being ethically right, wrong, or obligatory) belong to the actions themselves and are not to be explained as mere products of a mind that perceives and feels attracted to or repelled by the actions. In opposition to conventionalism, realism holds that scientific theories are objectively true (or false) based on their correspondence (or lack or it) to an independently existing reality.
Excerpted from: Stevens, Mark A., Ed. Merriam-Webster’s Collegiate Encyclopedia. Springfield, Massachusetts: Merriam-Webster, 2000.