Any view holding that some of our knowledge is got by a direct process not depending on the senses and not open to rational assessment.
The objects of such knowledge may include: moral principles (whether as the basis of duty or as ultimate values); particular moral duties on a particular occasion (sometimes called perceptual intuitionism); space and time and their contents, so far as these are presented to us independently of anything contributed by the understanding (Immanuel Kant (1724-1804)), reality as it is itself, as opposed to reality processed by us for practical purposes (investigated by Henri Bergson (1859-1941)); things known by accumulated but forgotten experience or unconscious inference ('woman's intuition'; but this figures less prominently in philosophy); basic truths of logic and the principles of valid inference.
An important special case of the last example cited above is the mathematical intuitionism of Luitzen Egbertus Jan Brouwer (1881-1966) and AREND HEYTING (1898-1980), a form of constructivism which insists that we should assert only what can be proved (by intuitively acceptable steps) and deny only what can be disproved.
Also see: anti-realism
D Pole, Conditions of Rational Inquiry (1961), ch. 1