Synthetic judgment a priori

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The expression “ synthetic judgment a priori ” comes from the philosophy of Immanuel Kant . Kant uses it to designate judgments that are not made on the basis of experience, i.e. are a priori , and whose truth is not based on the decomposition of concepts (as in the case of analytical judgments ) . According to Kant, pure synthetic a priori judgments are the goal of scientific metaphysics . Insofar as this metaphysics also describes the structures of everyday knowledge, it also contains synthetic a priori judgments. The question of how we come to such judgments and under what conditions they are true occupies a central place in Kant's epistemology .

This article follows the distinctions presented in the introduction to the second edition (B) of the Critique of Pure Reason .

Judge a priori and a posteriori

For Kant, truthful knowledge takes place in judgments. As judgments, Kant describes the mental connection of concepts or other judgments that may be problematic, true ("assertoric") or even necessary. In the simplest case of the categorical judgment , a subject (in the sense of Greek  ὑποκείμενον ) is assigned a predicate , e.g. B. “The gray horse is three years old”. Judgments that can only be made after experience are what Kant calls “judgments a posteriori ” ( Latin a posteriori , “in retrospect”). Judgments that are not based on experience are what Kant calls “judgments a priori” ( Latin a priori , “from the start”). They come from the mind of the knower himself.

One recognizes judgments a priori

  1. their necessity : they cannot be wrong, their negation contains a logical or real contradiction.
  2. to the strict generality : they apply without exception and under all circumstances.

Judgments a posteriori describe reality, but without necessity and generality: It is conceivable that it would be different; the facts described do not apply to all cases of the subject or not for all time. Based on experience, only comparatively general judgments can be made through inductive generalization, for which it cannot be ruled out that there are exceptions. They are rules, but not laws .

A classic example is “All swans are white.” This judgment comes from experience and had to be held to be generally valid in Europe until the discovery of Australia when news of the existence of black swans reached Europe. Since the zoological term "swan" does not allow the exclusion of black swans, the judgment turned out to be wrong - it only applied to all previously observed cases.

A special subgroup of the a priori judgments Kant describes as “ pure a priori judgments”. In these judgments, not only is the connection between ideas independent of experience, but also the ideas themselves: they must not be empirical ideas.

Synthetic and analytical judgments

There are numerous unproblematic examples of a priori judgments. Regardless of experience, z. B. the judgment: "Molds have a white fur". The reason for this is that the term mold already includes the fact that they have a white fur. Otherwise it wouldn't be mold. Kant calls such judgments "analytical". Analytical judgments formulate something that is already contained in the intension of the term. They explain the term in the subject position, but do not contain any new information about it.

Kant distinguishes "synthetic judgments" from analytical judgments. Synthetic judgments connect a subject with a predicate that is not already included in the concept of the subject. So synthetic judgments are cognitions that “expand” our knowledge insofar as a previously unknown property of the subject is determined. There is also a class of straightforward examples here: the synthetic a posteriori judgments. The judgment “The gray horse is three years old”, which is made on the basis of the acquaintance with a certain gray horse, i.e. a posteriori, is true if, on the basis of the acquaintance with the subject of the sentence (i.e. the given horse), the judgment is correctly applied the two terms “gray” and “three-year-old” can be ascribed to this horse.

Synthetic judgments a priori

Kant was concerned with developing criteria for the possibility and validity of general and necessary judgments that are independent of experience without being merely analytical. Only judgments that meet these criteria can deal with the subject area of ​​traditional metaphysics. But the possibility of non-analytical necessary judgments was also important for everyday knowledge and science (see also the induction problem ).

In order to show that there are purely synthetic judgments a priori, Kant refers to pure mathematics , the judgments of which, according to him, are “entirely synthetic” (cf. Immanuel Kant: AA III, 37-39). Traditionally, they were considered a priori judgments. For geometrical judgments, Kant's argument seems easily comprehensible; but he also mentions the “arithmetic sentence” “7 + 5 = 12” as an example. Since the text is opaque at this point, the problem of the interpreters' arithmetic judgments is often Immanuel Kant: AA III, 137, Immanuel Kant: AA III, 149–151, Immanuel Kant: AA III, 471 and Immanuel Kant: AA IV, 283 consulted. According to the usual reading, arithmetic is based on a pure intuition in time, since the concept of number is genetically formed from the successive addition of repetitive units, and thus presupposes time as a form of intuition. In the concept of seven, in the concept of five, and in the union of these concepts, the twelve is not included. Only with the help of intuition is it possible to go beyond purely analytical judgments of the concepts seven and five and to think of the number twelve as the sum of seven and five. “7 + 5 = 12” is therefore a synthetic judgment a priori in a pure science of reason. Kant sets the condition that metaphysics can only arrive at certain new knowledge if here, too, synthetic judgments a priori can be found. Only then does it have the status of a science.

The central question of Kant's epistemology, however, is how synthetic a priori judgments (i.e. knowledge based on pure reason) are generally possible. The “Transcendental Aesthetics” and the “Transcendental Analytic” in Kant's Critique of Pure Reason are dedicated to answering this question . The consequences are considered by the “ Transcendental Dialectic ”, the application to philosophy as a research program and as a historical project results from the “Transcendental Methodology”.

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Individual evidence

  1. ↑ Immanuel Kant, Collected Writings. Ed .: Vol. 1-22 Prussian Academy of Sciences, Vol. 23 German Academy of Sciences in Berlin, from Vol. 24 Academy of Sciences in Göttingen, Berlin 1900ff., AA III, 37–39  / B 14-17.
  2. ↑ Immanuel Kant, Collected Writings. Ed .: Vol. 1-22 Prussian Academy of Sciences, Vol. 23 German Academy of Sciences in Berlin, from Vol. 24 Academy of Sciences in Göttingen, Berlin 1900ff., AA III, 137  / B 182f.
  3. ↑ Immanuel Kant, Collected Writings. Ed .: Vol. 1-22 Prussian Academy of Sciences, Vol. 23 German Academy of Sciences in Berlin, from Vol. 24 Academy of Sciences in Göttingen, Berlin 1900ff., AA III, 149–151 .
  4. ↑ Immanuel Kant, Collected Writings. Ed .: Vol. 1-22 Prussian Academy of Sciences, Vol. 23 German Academy of Sciences in Berlin, from Vol. 24 Academy of Sciences in Göttingen, Berlin 1900ff., AA III, 471  / B 745.
  5. ↑ Immanuel Kant, Collected Writings. Ed .: Vol. 1-22 Prussian Academy of Sciences, Vol. 23 German Academy of Sciences in Berlin, from Vol. 24 Academy of Sciences in Göttingen, Berlin 1900ff., AA IV, 283  / Prolegomena , § 10.
  6. ↑ Monck already reads the example “7 + 5 = 12” in such a way that the reconstruction of the truth of this judgment leads to additions such as “1 + 1 + 1 + 1 + 1 = 5”, which requires a synthetic judgment. See WHS Monck: Kant's Theory of Mathematics. In: Mind 8/32 (1883), 576-578.