Reason versus Sense Perception From the 17 th century to the late 19 th century, the primary debate in epistemology was the supremacy of rationalism versus empiricism . Rationalism was a system of thought that emphasized the role of reason and a priori principles in obtaining knowledge. Rationalism appeared in some form in nearly every stage of Western philosophy, but it is primarily identified with the tradition of French philosopher and scientist Descartes. Cartesian rationalism was further developed by other European philosophers such as Spinoza and Leibniz. Empiricism is a doctrine that affirms that all knowledge is based on experience, especially sense perception, and on a posteriori principles.
Empiricism denies the possibility of spontaneous ideas or a priori thought.
The term empiricism originally applied to those views held by English philosophers such as Bacon and Locke. For the early rationalists Descartes, Spinoza, and Leibniz the main source and final test of knowledge was deductive reasoning based on self-evident principles, or axioms. Bacon inaugurated the new era of modern science by criticizing the medieval reliance on tradition and authority. He also established new rules of scientific method, including the first set of rules of inductive logic ever formulated. Berkeley agreed with Locke that knowledge comes through ideas, but he denied Locke's belief that a distinction can be made between ideas and objects.