In the history of philosophy, the term “rationalism” has…

““In the history of philosophy, the term “rationalism” has two distinct meanings. In one sense, it signifies an unbreached commitment to reasoned thought in contrast to any irrationalist rejection of the mind. In this sense, Aristotle and Ayn Rand are preeminent rationalists, opposed to any form of unreason, including faith. In a narrower sense, however, rationalism contrasts with empiricism as regards the false dichotomy between commitment to so-called “pure” reason (i.e., reason detached from perceptual reality) and an exclusive reliance on sense experience (i.e., observation without inference therefrom). Rationalism, in this sense, is a commitment to reason construed as logical deduction from non-observational starting points, and a distrust of sense experience (e.g., the method of Descartes). Empiricism, according to this mistaken dichotomy, is a belief that sense experience provides factual knowledge, but any inference beyond observation is a mere manipulation of words or verbal symbols (e.g., the approach of Hume ). Both Aristotle and Ayn Rand reject such a false dichotomy between reason and sense experience; neither are rationalists in this narrow sense. Theology is the purest expression of rationalism in the sense of proceeding by logical deduction from premises ungrounded in observable fact—deduction without reference to reality. The so-called “thinking” involved here is purely formal, observationally baseless, devoid of facts, cut off from reality. Thomas Aquinas, for example, was history’s foremost expert regarding the field of “angelology.” No one could match his “knowledge” of angels, and he devoted far more of his massive Summa Theologica to them than to physics.””

— Andrew Bernstein