  The rationalism of the most famous of the rationalists is problematic on two counts. First, Descartes is known as the father of modern philosophy precisely because he initiated the so-called epistemological turn that is with us still. Since Descartes, philosophy has been especially concerned with the theory of knowledge, both in itself and as it affects other areas of philosophy. Ethics, for example, has often been concerned with how the good might be known rather than with what the good might be. With his fundamental objective of achieving certainty for his beliefs, Descartes has thus been principally responsible for the incomplete characterization of rationalism as not just etymologically but essentially connected to the claims of reason. While Descartes certainly sought to justify the claims of reason and relied upon them, even for him there are corresponding ontological views that are no less important to his system.