a priori

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a priori

1. Logic relating to or involving deductive reasoning from a general principle to the expected facts or effects
2. Logic known to be true independently of or in advance of experience of the subject matter; requiring no evidence for its validation or support

A Priori


knowledge that precedes experience and is independent of it.

The term “a priori” was introduced by the medieval scholastic philosophers, who emphasized that certain kinds of knowledge precede experience. Later, especially after Leibniz, the independence of a priori knowledge from experience came to the fore, as well as its purely speculative, conceptual origin. According to Descartes and Leibniz, the most profound knowledge is attained apart from experience, by means of looking at the truth directly, that is, by intellectual intuition, which constitutes one of the principal “faculties of the soul.” Behind the formulation of the problem in this way, there was a correct insight that the process of cognition is not a simple photographing of reality and that man not only reflects the world but also creates it (V. I. Lenin, Poln. sobr. soch., 5th ed., vol. 29, p. 194). This led to searching in consciousness itself for those factors that could serve as premises for cognitive activity. Therefore, attempts to distinguish a priori knowledge have reflected a striving to distinguish the inner source of active thought. This line achieved its greatest development in Kant’s system, in which a priori knowledge was regarded as a condition of the necessity and the universality of experimental knowledge. In this system, as distinct from his predecessors, Kant maintained that a priori knowledge is not knowledge itself but rather the form through which knowledge is received; thus, it has meaning only within the bounds of experience. Kant’s concept of a priori, however, not to speak of the concepts of his predecessors, in fact rigidly dissociated the two forms of cognition, a priori and a posteriori. Hence it failed to provide a satisfactory solution to the problem of the source and form of thought. In the subsequent development of philosophy this formulation of the problem was accepted, but the concept of a priori itself was subjected to criticism. Moreover, such criticism was made in various and even contradictory directions, depending upon which school was undertaking it.

While dialectical materialism accepts the thesis concerning the active nature of cognition and develops the idea of its social nature, it has rejected the idea of a priori as a principle for explaining the nature of knowledge. As the basis for its own theory of cognition, it has posited the thesis that in the final analysis all kinds of knowledge have their origin in practical experience. According to dialectical materialism all knowledge is a reflection of objective reality; but in this process the subject does not obtain knowledge of the reality directly but rather through practical experience, that is, through an activity in which the consciousness does not simply reproduce the facts of experience but actively and creatively refines them. Because of this, any concrete knowledge (or form of thought) can arise directly not only from experience but from other knowledge, and in this sense it can show traces of a priori knowledge. In such a case its experiential and a posteriori origin is revealed only in historical perspective.


Kant, I. Kritika chistogo razuma. Soch., vol. 3. Moscow, 1964.
Spirkïn, A. G. Kurs marksistskoi filosofii, 2nd ed. Moscow, 1966. Chapter 5.


a priori

[¦ā prē¦ȯr·ē]
Pertaining to deductive reasoning from assumed axioms or supposedly self-evident principles, supposedly without reference to experience.
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h]) is used in the following lemma and will be an essential part in the derivation of the a-priori estimates in Section 5.
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