In philosophy, rationalism is the epistemological view that "regards reason as the chief source and test of knowledge" or "any view appealing to reason as a source of knowledge or justification". More formally, rationalism is defined as a methodology or a theory "in which the criterion of the truth is not sensory but intellectual and deductive".
- A prerequisite for a fruitful study of the rationalist, then, is a readiness to be open-minded, and a willingness to discard some of the caricatures from which 'rationalism' has sufferde in our own time. Many of the distortions arise from a tendecy to see rationalism as a kind of seemless web, so that any philosopher whose thought contains rationalist elements is seen as being committed to the wildest excesses of speculative metaphysics. What should by now be starting to emerge is that 'rationalism' stands not for a monolithic philosophical doctrine, but rather for a cluster of overlapping views and ideas.
- John Cottingham, Rationalism (1984), p. 10
- Rationalism... is a secularized form of the belief in the power of the word of God.
- Paul Feyerabend, Against Method (1975) p. 227
- It is no accident that Cartesian rationalism was completely blind to the forces of historical evolution. And what it applied to the past it proclaimed as programme for the future: that man in the full knowledge of what he was doing should deliberately create such a civilization and social order as the process of his reason enabled him to design. Rationalism in this sense is the doctrine which assumes that all institutions which benefit humanity have in the past and ought in the future to be invented in clear awareness of the desirable effects that they produce; that they are to be approved and respected only to the extent that we can show that the particular effects they will produce in any given situation are preferable to the effects another arrangement would produce; that we have it in our power so to shape our institutions that of all possible sets of results that which we prefer to all others will be realized; and that our reason should never resort to automatic or mechanical devices when conscious consideration of all factors would make preferable an outcome different from that of the spontaneous process. It is from this kind of social rationalism or constructivism that all modern socialism, planning and totalitarianism derives.
- Friedrich Hayek, "Kinds of Rationalism", The Economic Studies Quarterly (1965)