 concepts |  Descartes, René |  Descartes, René: epistemology |  Descartes, René: theory of ideas |  Hume, David |  innateness: and contemporary theories of cognition |  innateness: and language |  Leibniz, Gottfried Wilhelm |  Locke, John |  Plato: middle period metaphysics and epistemology |  rationalism vs. empiricism 