Rationalism is defined as reliance on reason {Lat. ratio} as the only reliable source of human knowledge. In the most general application, rationalism offers a naturalistic alternative to appeals to religious accounts of human nature and conduct.
More specifically, rationalism is the epistemological theory that significant knowledge of the world can best be achieved by a priori means; it therefore stands in contrast to empiricism. Prominent rationalists of the modern period include Descartes, Spinoza, and Leibniz. [from www.philosophypages.com
Belief that material objects exist independently of our perception of them. (Thus, opposed to idealism.) Realistic theories of perception include both representationalism, in which awareness of objects is mediated by our ideas of them, and direct realism, which presumes an immediate relation between observer and observed.
Capable of being indefinitely re-applied to the results of its own application. Hence, a recursive definition is one that begins with one or more initial instances and then specifies the repeatable rules for deriving others. Thus, for example:
"A person's descendants include that person's children and all of their descendants" is a recursive definition [not a circular definition] of the word "descendant".
Belief that statements or expressions of one sort can be replaced systematically by statements or expressions of a simpler or more certain kind. Thus, for example, some philosophers have held that arithmetic can be reduced to logic, that the mental can be reduced to the physical, or that the life sciences can be reduced to the physical sciences.
Reliance on experience as the source of ideas and knowledge. More specifically, empiricism is the epistemological theory that genuine information about the world must be acquired by a posteriori means, so that nothing can be thought without first being sensed. Prominent modern empiricists include Bacon, Locke, Berkeley, Hume, and Mill. In the twentieth century, empiricism principles were extended and applied by the pragmatists and the logical positivists.
An eighteenth-century movement that placed great emphasis on the use of reason in the development of philosophical, social, political, and scientific knowledge. Enlightenment philosophers include Bayle, Hume, Wollstonecraft, Kant, and many lesser figures.
Branch of philosophy that investigates the possibility, origins, nature, and extent of human knowledge. Although the effort to develop an adequate theory of knowledge is at least as old as Plato's Theaetetus, epistemology has dominated Western philosophy only since the era of Descartes and Locke, as an extended dispute between rationalism and empiricism over the respective importance of a priori and a posteriori origins. Contemporary postmodern thinkers (including many feminist philosophers) have proposed the contextualization of knowledge as part of an intersubjective process.