Learn more about Rationalism
In philosophy and in its broadest sense, rationalism is "any view appealing to reason as a source of knowledge or justification" (Lacey, 286). In more technical terms it is a method or a theory "in which the criterion of truth is not sensory but intellectual and deductive" (Bourke, 263). Different degrees of emphasis on this method or theory lead to a range of rationalist standpoints, from the moderate position "that reason has precedence over other ways of acquiring knowledge" to the radical position that reason is "the unique path to knowledge" (Audi, 771).
In various contexts, the appeal to reason is contrasted with revelation, as in religion, or with emotion and feeling, as in ethics. In philosophy, however, reason is more often contrasted with the senses, including introspection but not intuition (Lacey, 286).
Within the Western philosophical tradition, "rationalism begins with the Eleatics, Pythagoreans, and Plato, whose theory of the self-sufficiency of reason became the leitmotif of Neoplatonism and idealism" (Runes, 263). Since the Enlightenment, rationalism is usually associated with the introduction of mathematical methods into philosophy, as in Descartes, Leibniz, and Spinoza (Bourke, 263). This is commonly called continental rationalism, because it was predominant in the continental schools of Europe, whereas in Britain empiricism dominated.
Rationalism is often contrasted with this view known as empiricism. Taken very broadly these views are not mutually exclusive, since a philosopher can be both rationalist and empiricist (Lacey, 286–287). Taken to extremes the empiricist view holds that all ideas come to us through experience, either through the five external senses or through such inner sensations as pain and pleasure, and thus that knowledge is essentially based on or derived from experience. At issue is the fundamental source of human knowledge, and the proper techniques for verifying what we think we know (see Epistemology).
Proponents of some varieties of rationalism argue that, starting with foundational basic principles, like the axioms of geometry, one could deductively derive the rest of all possible knowledge. The philosophers who held this view most clearly were Baruch Spinoza and Gottfried Leibniz, whose attempts to grapple with the epistemological and metaphysical problems raised by Descartes led to a development of the fundamental approach of rationalism. Both Spinoza and Leibniz asserted that, in principle, all knowledge, including scientific knowledge, could be gained through the use of reason alone, though they both observed that this was not possible in practice for human beings except in specific areas such as mathematics. On the other hand, Leibniz admitted that "we are all mere Empirics in three fourths of our actions" (Monadology § 28, cited in Audi, 772).
 Philosophical usage
The distinction between rationalists and empiricists was drawn at a later period, and would not have been recognized by the philosophers involved. Also, the distinction was not as clear-cut as is sometimes suggested; for example, the three main rationalists were all committed to the importance of empirical science, and in many respects the empiricists were closer to Descartes in their methods and metaphysical theories than were Spinoza and Leibniz.
 History of rationalism
 Classical Greek rationalists
 Socrates (ca 470–399)
Socrates firmly believed that, before anyone can understand the world, they first need to understand themselves. And the only way to accomplish that is with rational thought. Socrates did not publish or write any of his thoughts, but he was constantly in discussion with others. He would usually start by asking a (seemingly answerable) question, to which the other would give an answer. Socrates would then continue to ask questions until all conflicts were resolved, or until the other could do nothing else but admit he didn't know the answer (which was what most of his discussions ended with). Socrates did not claim to know the answers, but that did not take away the ability to critically and rationally approach problems.
 René Descartes (1596–1650)
Descartes thought that only knowledge of eternal truths – including the truths of mathematics, and the epistemological and metaphysical foundations of the sciences – could be attained by reason alone; other knowledge required experience of the world, aided by the scientific method. He also argued that although dreams appear as real as sense experience, these dreams cannot provide persons with knowledge. Also, since conscious sense experience can be the cause of illusions, then sense experience itself can be doubtable. As a result, Descartes deduced that a rational pursuit of truth should doubt every belief about reality. He elaborated these beliefs in such works as Discourse on Method, Meditations on First Philosophy, and Principles of Philosophy. Descartes developed a method to attain truths according to which nothing which cannot be recognised by the intellect (or reason) can be classified as knowledge. These truths are gained "without any sensory experience", according to Descartes. Truths that are attained by reason are to be broken down into elements which intuition can grasp, which, through a purely deductive process, will result in clear truths about reality.
Descartes therefore argued, as a result of his method, that reason alone determined knowledge, and that this could be done independently of the senses. For instance, his famous dictum, cogito ergo sum, is a conclusion reached a priori and not through an inference from experience. This was, for Descartes, an irrefutable principle upon which to ground all forms of other knowledge. Descartes posited a metaphysical dualism, distinguishing between the substances of the human body ("res extensa") and the mind or soul ("res cogitans") . This crucial distinction would be left unresolved and lead to what is known as the mind-body problem, since the two substances in the Cartesian system are independent of each other and irreducible.
 Baruch Spinoza (1632–1677)
Baruch Spinoza, a key precursor to the Age of Enlightenment, offered both a solution to the mind-body problem and determined the relationship between God as an infinite substance with the finite substance of the world. As a corollary of this, God is the only being that exists, of necessity, and the empirical world is just modifications of the infinite attributes of God, of which we are aware by thought and reason. God, as infinite substance and as made up of infinite attributes, necessarily exists, and is the whole of nature, or deus sive natura (God or nature).
In opposition to Descartes, Spinoza argued that there is only one substance, and that this is God when conceived under the attribute of thought, natura naturans, and Nature when conceived under the attribute of extension, natura naturata. Natura naturans is the eternal, aspect of Spinoza's system, and natura naturata is the infinite modifications of God's attributes. This God is non-personal, and has no will; Spinoza's universe is deterministic. Therefore, every human mind is part of God under the attribute of thought.
 Gottfried Leibniz (1646–1716)
Leibniz was the last of the great Rationalists, who contributed heavily to other fields such as mathematics. His system however was not developed independently of these advances. Leibniz rejected Cartesian dualism, and denied the existence of a material world. In Leibniz's view there are infinitely many simple substances, which he called "monads" (possibly taking the term from the work of Anne Conway).
Leibniz developed his theory of monads in response to both Descartes and Spinoza. In rejecting this response he was forced to arrive at his own solution. Monads are the fundamental unit of reality, according to Leibniz, constituting both inanimate and animate things. These units of reality represent the universe, though they are not subject to the laws of causality or space (which he called "well-founded phenomena"). Leibniz therefore introduced his principle of pre-established harmony, in order to account for apparent causality in the world.
 Immanuel Kant (1724–1804)
Immanuel Kant started as a traditional rationalist, having studied the rationalists Leibniz and Wolff, but after studying David Hume's works which "awoke [him] from [his] dogmatic slumbers", he developed a distinctive and very influential rationalism of his own which attempted to synthesise the traditional rationalist and empiricist traditions.
 Primary sources
- Descartes, René (1637), Discourse on Method.
- Spinoza, Baruch (1677), Ethics.
- Leibniz, Gottfried (1714), Monadology.
- Kant, Immanuel, (1781/1787), Critique of Pure Reason.
 Secondary sources
- Audi, Robert (ed., 1999), The Cambridge Dictionary of Philosophy, Cambridge University Press, Cambridge, UK, 1995. 2nd edition, 1999.
- Blackburn, Simon (1996), The Oxford Dictionary of Philosophy, Oxford University Press, Oxford, UK, 1994. Paperback edition with new Chronology, 1996.
- Bourke, Vernon J. (1962), "Rationalism", p. 263 in Runes (1962).
- Lacey, A.R. (1996), A Dictionary of Philosophy, 1st edition, Routledge and Kegan Paul, 1976. 2nd edition, 1986. 3rd edition, Routledge, London, UK, 1996.
- Runes, Dagobert D. (ed., 1962), Dictionary of Philosophy, Littlefield, Adams, and Company, Totowa, NJ.
 See also
 External links
- Markie, Peter (2004), "Rationalism vs. Empiricism", Stanford Encyclopedia of Philosophy, Edward N. Zalta (ed.),
- John F. Hurst (1867), History of Rationalism Embracing a Survey of the Present State of Protestant Theology