Christo Stoev

A priori is that formally determined knowledge (or component of knowledge) that contains nothing belonging to sensation and that respectively is independent of any experience and does not have its origin in experience.

In Latin “a priori” means “from what comes before” or “from the former” and in a cognitive context means “before experience”, “coming before with regard to experience”. Paradoxically, this coming-before, in transcendental philosophy, should not be understood temporally, i. e., what comes before experience is not available before experience in terms of time. Kant himself notes that “temporally no knowledge in us precedes experience and all knowledge begins with it”. However, the fact that all our knowledge begins with (mit) experience in no way means that it all originates from (aus) experience. It is precisely that knowledge of ours which does not originate from experience although it begins with experience that is a priori. That fine distinction of Kant’s is to be understood as stating that our cognitive capacity with its specific structures is “incited to action” by experience and only thus it is actualized in experience. In this sense its a priori forms start to operate together with experience though they do not originate from it but formally precede it. Hence the following formulation can be suggested: the a priori is not before experience actually (in actu), but precedes experience only in power, in possibility (in virtu).

With a view to the above we can emphasize that the first characteristic of the a priori is purely negative – the a priori itself is not experiential, is not empirical, does not originate in the components of the experience itself, although it is actualized with experience. Thus, Kant characterizes a priori knowledge as “independent of experience and even of all sense impressions”. What, however, comprises the truly empirical component in experience, abstracted from all the a priori forms realized in it is, in the end, the component of sensation. That is why, the a priori is that in which, considered in itself, there is nothing that belongs to the sensation or that is reducible to sensations. (Pure (rein) is called that which, apart from being a priori, has nothing empirical mixed with it.)

In addition to the negative characterization, it should be emphasized that the a priori has one substantial positive characteristic, namely, that it has a formal character in contrast to the “raw matter” of sense impressions that comprises the contentful nature of experience itself. In this sense, Kant notes that the “form of the appearance” “has to be ready for all appearances in the mind a priori”. In fact, the a priori is the formal structure-giving side in the whole of our cognition. This is so because experience itself (the sphere of the empirical) cannot offer the form of an object but only the matter for its cognition. This in effect is one of the central tenets in Kant’s transcendental philosophy – experience is never capable of yielding a ready and complete object, such an object is always a question of rational determination and in this sense of cognitive activity. In other words, for Kant experience is not grounded in itself, it has its extra-experiential grounds of validity. These extra-experiential (non-empirical) and therefore transcendental grounds of validity consist of precisely in the formal-structuring activity of our cognitive capacities, whose specific determination is available before, i. e. a priori any concrete empirical object. That is why in every complete empirical object there are a priori components that comprise its formal side or the “form of an object in general”.

The criterion of the a priori character of given knowledge or component of knowledge is its necessity and strict universality. Accordingly, Kant notes that “experience teaches us indeed that something is made in this or that way but not that it cannot be otherwise”. The possibility that something could be otherwise means that it is not necessary. That is why no experiential, empirical proposition is conceived together with its necessity. Only propositions that are valid a priori any experience can be conceived as necessary. Kant uses this criterion both with respect to intuitions (and the synthetic propositions based on them) and with respect to concepts and synthetic propositions from pure understanding).  


Kant, Immanuel (1974) Kritik der reinen Vernunft. – In: Werkausgabe in 12 Bänden. Band III/IV. Suhrkamp.

Kant, Immanuel (1998) Critique of Pure Reason, Cambridge: Cambridge University Press.

Allison, H. (2004) Kant’s Transcendental Idealism: An Interpretation and Defense, New Haven and London: Yale University Press, Revised and Enlarged Edition.

Höffe, O. (1994) Immanuel Kant, Albany: State University of New York Press.

How to Cite:

Stoev, Christo (2021) A priori, in: Thesaurus. Sofia University Dictionary of Philosophy. Online edition. Sofia: St. Kliment Ohridski University Press, 2021, ISSN 2815-2832.