as opposed to nominalism, the doctrine that genera and species are real things or entities, existing independently of our conceptions. according to realism the universal exists ante rem (plato), or in re (aristotle).-as opposed to idealism, the doctrine that in sense perception there is an immediate cognition of the external object, and our knowledge of it is not mediate and representative.-fidelity to nature or to real life; representation without idealization, and making no appeal to the imagination; adherence to the actual fact.