Notes on Kant's
Prolegomena to Any Future Metaphysics
in 44 Points

Contact: Dr. Jan Garrett

Last modified April 4, 2008

These notes refer to the translation of Kant's Prolegomena found in the Modern Philosophy anthology edited by Watkins and Ariew and published by Hackett Publishing Company in 1998.

1. Kant is interested in whether metaphysics, as a science consisting of synthetic a priori propositions, is at all possible. (Marginal page number 255)

2. Metaphysics would concern topics such as causality, substance, the universe as a whole, free will, the immortal soul, and God.

3. It is not expressed in analytic a priori judgments, or judgments whose predicate is contained in their subject and which can be discovered without the use of concrete experience. (266)

4. It is not expressed in synthetic a posteriori judgments, or judgments whose predicate adds something to the subject and which are only discovered through concrete experience. (266)

5. In Kant's view, Hume decisively showed that we have neither synthetic a posteriori (empirical) nor analytic a priori knowledge of causation. (257)

6. Kant asserts that pure mathematics is an example of synthetic a priori knowledge. Mathematical knowledge can proceed only by construction of concepts, in a mentally purified field of space and/or time. With the geometrical proposition "the whole is greater than its part," the predicate is necessarily joined to the subject and the mind brings in a purified intuition of space. (283-286)

7. Kant's transcendental philosophy (at one point called 'critical idealism') is nothing but the complete solution to the problem regarding the possibility of synthetic a priori propositions.

8. A human being's "intuition" can anticipate the actuality of a [sensible] object, because it supplies "the form of sensibility, which in me as subject precedes all the actual impressions through which I am affected by objects." (282)

9. The forms of sensuous intuition do not enable us to know things [as they are] in themselves; we know things only as they appear to us, as phenomena (283)

10. Geometry is based upon the form of intuition we call space and arithmetic is based upon the form of intuition we call time. (283)

11. The faculty of a priori intuition contain only the form of phenomena, not their matter or sensuous content. (284)

12. Some judgments rest directly on the a priori forms of intuition: that (complete) space has three dimensions; that a straight line can be drawn to infinity (284-85)

13. Kant notes that righthand and lefthand gloves, each the mirror of the other, are incongruent but indistinguishable except in terms of right and left, which are spatially relative to perceivers. He takes this as proof that space and time are not aspects of things in themselves. (285-86)

14. Propositions of geometry are not descriptions of things in themselves; nor is space "out there." It is in us and discovered there a priori; we all constitute it in the same way; for this reason we all are able to arrive at the same geometrical truths. (287-88)

15. Kant understands "nature" as the existence of things, so far as it is determined according to universal laws. Nature is knowable a posteriori, so Kant cannot mean by nature "what things are in themselves." (294)

16. He says "we possess a pure natural science . . . a priori . . . " ; it consists of propositions regarding nature independent of any experience of nature whatsoever and therefore independent of particular sensory observation. Its laws include: "substance is permanent" and "every event is determined by a cause according to constant laws." (295)

17. Kant distinguishes judgments of perception (JP), judgments that are valid to me because they correspond to how things are connected in my perception, from judgments of experience (JE), which result when JP's are transformed: This happens when JP's are be subsumed under the law that, whenever an event is observed, it is always related to some antecedent, which it follows according to a universal rule. In other words, JE's are formed when to the JP certain special concepts are added, e.g., that of the universal cause-effect connection. (298ff.)

Example: JP: when [what seems to be] the sun [apparently] shines on [what seems to be] the stone, it [apparently] grows warm. JE: The sun's shining on the stone causes it to grow warm.

18. The objectively valid character of the JE signifies its necessary universal validity, i.e., its objective validity for all subjects constituted as we are. (300-301)

19. Without the imposition of concepts of the understanding all our objectively valid synthetic judgments would be impossible. (301)

20. Kant claims he has derived a complete list of the pure a priori concepts of the understanding, without which experience would not be possible. (302)

21. He works from a list of the general attributes of judgments and applies them to the forms of intuition that create space and time. Causality is the reflection of the hypothetical judgment (the conditional, or if-then proposition) as applied to space and time.

22. Experience consists of intuitions, which belong to sensibility, and judgments, which are entirely the work of the understanding. (304)

23. "The pure concepts of the understanding" are those under which all perceptions must first be subsumed before they can serve for judgments of experience, in which the synthetic unity of the perceptions is represented as necessarily and universally valid. (305-306)

24. The question "How is a pure natural science possible?" is solved: The categories, which reflect the table of judgments, give a complete and necessary system for our a priori understanding of nature. (306)

25. We can now speak objectively of substance and cause-effect. We must think of objects within experience as subsumed under categories of substance and cause-effect, because without them we do not have coherent experience. These features of objects of experience are universally valid because all human subjects are so constituted as to impose them upon our intuitions. (Sections 25, 27)

26. We must not expect that these categories pertain to things in themselves; rather they pertain only to objects of experience constituted by the union of our intuitions and the categories.

27. We have discovered the definite bounds within which the concepts of substance, cause-effect, etc. legitimately apply. Application beyond these bounds (i.e., beyond experience) leads to what he calls transcendent illusion (313-14)

28. Phenomena are "things of sense, or appearances." Phenomena can be known, i.e., subsumed under the a priori concepts of understanding. Noumena are "things of the understanding, which make up an intelligible world." (314)

29. About noumena, we neither know nor can know anything determinate whatever. (314)

30. The understanding "transgress[es] with its otherwise legitimate concepts the bounds of their use" when the mind goes beyond experience to explore a much more extensive realm filled with pure noumena.

31. Transcendental philosophy can answer its highest question: How is nature possible? It does so by answering two related questions:

32. The first "How is nature possible in general in the material sense?" is answered thus: by means of the constitution of our sensibility (318)

33. The second "How is nature possible in the formal sense, as the totality of rules under which all appearances must come in order to be thought as connected in an experience?" is answered thus: by means of the constitution of our understanding, according to which all the representations of sensibility (percepts) are necessarily referred to a consciousness, and by the peculiar way in which we think (the a priori concepts). (318)

34. Other than concepts of nature, metaphysics has to do with pure concepts of reason, which can never be given in any possible experience whatsoever. (328ff.)

35. This activity of reason arises when reason broods over the concepts of understanding, without applying them to empirical appearances.

36. These pure concepts pertain to "transcendent" things: K. mean by "transcendent" what goes beyond every possible experience. "Ideas [of pure reason]" are necessary concepts whose objects cannot be given in any experience. (328)

37. The ideas are distinct from the categories because the latter can be discovered in experience (because we contribute them to it) and so confirmed in experience.

38. Psychological idea refers to the absolute subject of particular experiences projected beyond the presupposition of experience, i.e., life; that is, the psychological idea is that of the immortal soul. (333ff.)

39. Kant denies that the immortality of the soul can be proved. Permanence is a feature of substance, and this is something we know. But we know this only within experience because we contribute this notion a priori to appearances in order to constitute experience. The doctrine of the immortality of the soul applies the category beyond experience to the subject as a noumenon. We have no knowledge of this. (334-35)

40. The cosmological ideas are (1) whether or not the universe is infinite with respect to space and time; (2) whether or not material things are infinitely divisible; (3) whether or not there are "causes through freedom"; and (4) whether or not there is a necessary being in the series of causes. (338-39)

41. A theological idea is the idea of "a most perfect first being," i.e., God. (348)

42. According to Kant, there is a position more absurd than claiming to know something about noumena: that is to deny the existence of things in themselves and declaring our [human] experience to be the only possible way of knowing things. (350-51)

43. We are not at liberty to abstain from inquiring into what things in themselves may be, even though we cannot obtain a definite notion of what things in themselves are. (351)

44. We "think an immaterial being, a world of understanding and a Supreme Being" even though we can never know them as they are in themselves because in them only, as things in themselves, does reason find completion and satisfaction. (354-55)