Rationalism and empiricism are two approaches to epistemology which traditionally have been seen as standing in opposition to one another. Rationalists tend to believe that human reason is the chief source and arbiter of knowledge. This is usually accompanied by a belief in innate (i.e. unlearned) knowledge, and an underlying ability for human reason to grasp the logical structure of the universe and understand it through the exercise of the intellect. Empiricists, by contrast, tend to believe that empirical evidence derived through the senses is the primary source and ultimate arbiter of knowledge. They tend to deny innate knowledge, arguing that essentially all human beliefs are ultimately derived in one form or other through our sensory experiences. Empiricists will also typically disagree with rationalists that the human mind can grasp the logical structure of nature and arrive at firm knowledge though the application of intellect alone, arguing that most or all human knowledge is tentative and must be constantly subject to revision when new empirical evidence becomes available.
Rationalism and empiricism should be understood as loose tendencies and general methodological approaches, rather than as specific competing positions. There are many different conceptions about what exactly it means for knowledge to be based ‘on experience’, or to be derived ‘from reason’, and as to how evidence from the senses and rational thought relate to one another. Many philosophers would agree that both reason and empirical evidence are important in obtaining knowledge, though they may differ in their relative degree of emphasis or trust placed on one over the other. Traditionally, empiricism has been associated with thinkers such as John Locke, George Berkley, and David Hume, while rationalism is often associated with the works of Rene Descartes, Benedict de Spinoza, and Gottfried Leibniz.
Rationalism vs empiricism: informative video introduction to the distinction
Continental rationalism: an Internet Encyclopedia of Philosophy article covering the approaches and key ideas of the ‘Contential Rationalists’, with a focus on Spinoza, Descartes, and Leibniz
Rationalism: a useful outline of key rationalist thinkers and positions from philosophybasics.com
British empiricism: a useful outline of key empiricist thinkers and positions from philosophybasics.com
Rationalism vs. empricism: a detailed overview of core aspects of the debate from the Stanford Encyclopedia of Philosophy