Frome the Critique of Pure Reason:

"First, then, if a proposition is thought along with its ne­cessity, it is an a priori judgment; if it is, moreover, also not derived from any proposition except one that in turn is valid as a necessary proposition, then it is absolutely a priori."

I don´t understand the part about absolutely a priori.

He gives an example:

"Every alteration has its cause" (A priori but not absolutely)

How do we apply the definition of absolutely a priori to this example?

The example given is a proposition. An "alteration" is a change in space and time. This is another proposition. So the first one is derived from the second one. The second one is a necessary proposition, tough is almost the same than the first one. Anyhow, this comply with the definition given and should be absolutely a priori.


  • Can you give us a page number (in either the A or B edition)? Strikes me as a case of "bad translation".
    – Philip Klöcking
    Commented Feb 27, 2019 at 15:25
  • 1
    Page is B3. It's from the Cambridge Edition. Commented Feb 27, 2019 at 15:29
  • Not the time for an answer proper, but being derived is not enough. The proposition has to be derived only from a priori propositions.
    – Philip Klöcking
    Commented Feb 27, 2019 at 15:42
  • The former says something that we can imagine being different in experience. So it is not a priori. It is validated by our experience. If it were not seen to be true, we would not believe it. (And holders of various modern scientific theories that involve complete randomness, like the theory of virtual particles do not believe it.) The absolute a priori is not related to experience, if it were false, we would not be able to imagine why.
    – user9166
    Commented Feb 27, 2019 at 17:22

2 Answers 2


See the example above it, regarding the foundations of a house: that undermining the foundations of his house would cause it to fall can be asserted before he actually did it.

This is not a "real" a priori knowledge, also if we can predict the fall of the house "prior to" the event, because experience is required to know that bodies are heavy and the effects of heaviness.

The "real" a priori knowledge that Kant is defining is knowledge that is prior to all experience, not just prior to some particular experiences.

Kant specifies that by "pure" (i.e. absolute) a priori cognition he means cognition having "no connections with anything empirical.”

In this sense, the statement "Every alteration [i.e. change] has its cause" is not pure in this sense because, according to Kant, the concept of "change" can be derived only from experience of events in time: thus we cannot assert something about change "prior to" every experience.

See also Kant’s Theory of Judgment : A priori judgments and a posteriori judgments :

a cognition is a priori, non-empirical, or absolutely independent of all sensory impressions and/or contingent natural objects or facts just in case it is not strictly determined in its form or in its semantic content by sensory impressions and/or contingent natural objects or facts and is instead strictly determined in its form or in its semantic content by our innate spontaneous cognitive faculties (B2–3).

It should be noted that the apriority of a cognition in this sense is perfectly consistent with all sorts of associated sensory impressions and also with the actual presence of sensory matter in that cognition, caused by contingent natural objects or facts, so long as neither the form nor the semantic content is strictly determined by those sensory impressions and/or contingent natural objects or facts.

“Pure” a priori cognitions are those that in addition to being a priori or absolutely independent of all sensory impressions and/or contingent natural objects or facts, also contain no sensory matter whatsoever (B3). So in other words, some but not all a priori cognitions are pure.

We must consider that, according to Kant, there are judgments and there are concepts, and both can be a priori.

Thus, IMO, the apparent (maybe, real ?) tension in Kant's example can be elucidated this way: a priori judgment must be necessary and strictly universal (B3).

According to this definition, the judgment "Every alteration has a cause", is a priori.

But it is not "pure" because it contains a concept, that of alteration, that is not itself a priori.

  • From B18: " in all alterations of the corporeal world the quantity of matter remains unaltered". According to Kant this proposition is a priori, but since it contains the concept of alteration which is empirical, is not absolutely a priori. It is correct? In B4: "Thus if a judgment is thought in strict universality, i.e., in such a way that no exception at all is allowed to be possible, then it is not derived from ex­perience, but is rather valid absolutely a priori". This supposes a contradiction with the former definition. The example from B18 would be absolutely a priori. Commented Feb 27, 2019 at 18:12

Kant distinguishes the two terms „concept“ and „proposition“:

„Every alteration has its cause“(B3) is a proposition, while „alteration“ and „cause“ are two concepts.

According to Kant the above proposition is a priori, but not pure (= absolute) a priori. Because the proposition builds on the concept „alteration“, which is not a priori.

At page B4 Kant refers again to the proposition „Every alteration has its cause“. Apparently it is not the proposition which is pure a priori. Kant argues that the second concept „cause“ is pure a priori. At B106 he names the category „Of Causality and Dependence“. Categories are pure concepts which apply a priori.

IMO Kant does not give an example of a proposition which is pure a priori. Instead he gives an example of a concept that is pure a priori.

For the whole issue see also https://www.reddit.com/r/askphilosophy/comments/81nrtu/absolutely_a_priori_vs_a_priori/

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