Prolegomena to Any Future Metaphysics That Will Be Able to Present Itself as a Science () is a book by German philosopher Immanuel Kant, published in 1783, two years after the first edition of his Critique of Pure Reason. One of Kant's shorter works, it contains a summary of the Critique‘s main conclusions, sometimes by arguments Kant had not used in the Critique. Kant characterizes his more accessible approach here as an "analytic" one, as opposed to the Critique‘s "synthetic" examination of successive faculties of the mind and their principles.Analytic and synthetic methods are not the same as analytic and synthetic judgments. The analytic method proceeds from the known to the unknown. The synthetic method proceeds from the unknown to the known. In §§ 4 and 5, Kant asserted that the analytic method assumes that cognitions from pure reason are known to actually exist. We start from this trusted knowledge and proceed to its sources which are unknown. Conversely, the synthetic method starts from the unknown and penetrates by degrees until it reaches a system of knowledge that is based on reason.
The book is also intended as a polemic. Kant was disappointed by the poor reception of the Critique of Pure Reason, and here he repeatedly emphasizes the importance of its critical project for the very existence of metaphysics as a science. The final appendix contains a response to an unfavorable review of the Critique.
Contents
Introduction Kant declared that the Prolegomena are for the use of both learners and teachers as an heuristic way to discover a science of metaphysics. Unlike other sciences, metaphysics has not yet attained universal and permanent knowledge. There are no standards to distinguish truth from error. Kant asked, "Can metaphysics even be possible?"
David Hume investigated the problem of the origin of the concept of causality. Is the concept of causality truly independent of experience or is it learned from experience? Hume mistakenly attempted to derive the concept of causality from experience. He thought that causality was really based on seeing two objects that were always together in past experience. If causality is not dependent on experience, however, then it may be applied to metaphysical objects, such as an omnipotent God or an immortal soul. Kant claimed to have logically deduced how causality and other pure concepts originate from human understanding itself, not from experiencing the external world.
Unlike the Critique of Pure Reason, which was written in the synthetic style, Kant wrote the Prolegomena using the analytical method. He divided the question regarding the possibility of metaphysics as a science into three parts. In so doing, he investigated the three problems of the possibility of pure mathematics, pure natural science, and metaphysics in general. His result allowed him to determine the bounds of pure reason and to answer the question regarding the possibility of metaphysics as a science.
Preamble on the peculiarities of all metaphysical knowledge § 1. On the sources of metaphysics
Metaphysical principles are a priori in that they are not derived from external or internal experience. Metaphysical knowledge is philosophical cognition that comes from pure understanding and pure reason.
§ 2. Concerning the kind of knowledge which can alone be called metaphysical
a. On the distinction between analytical and synthetical judgments in general
Analytical judgments are explicative. They express nothing in the predicate but what has already been actually thought in the concept of the subject. Synthetical judgments are expansive. The predicate contains something that is not actually thought in the concept of the subject. It amplifies knowledge by adding something to the subject's concept.
b. The common principle of all analytical judgments is the law of contradiction
The predicate of an affirmative analytical judgment is already contained in the concept of the subject, of which it cannot be denied without contradiction. All analytical judgments are a priori.
c. Synthetical judgments require a principle that is different from the law of contradiction.
1. Judgments of experience are always synthetical.
Analytical judgments are not based on experience. They are based merely on the subject's concept.
2. Mathematical judgments are all synthetical.
Pure mathematical knowledge is different from all other a priori knowledge. It is synthetical and cannot be known from mere conceptual analysis. Mathematics require the intuitive construction of concepts. This intuitive construction implies an a priori view of the concept constructed in the mind. In the Critique of Pure Reason, Kant elaborates on this, explaining that "to construct a concept means to exhibit a priori the intuition corresponding to it.” Arithmetical sums are the result of the addition of intuited counters. Geometrical concepts, such as "shortest distance," are known only through exhibiting the concept in pure intuition.
Some other principles, assumed by geometers, are indeed actually analytical, and depend on the law of contradiction; but they only serve, as identical propositions, as a method of concatenation, and not as principles, e.g., a = a, the whole is equal to itself, or a + b > a, the whole is greater than its part. And yet even these, though they are recognised as valid from mere concepts, are only admitted in mathematics, because they can be represented in some visual form (Anschauung). What usually makes us believe that the predicate of such apodeictic8 judgments is already contained in our concept, and that the judgment is therefore analytical, is the duplicity of the expression, requesting us to think a certain predicate as of necessity implied in the thought of a given concept, which necessity attaches to the concept. But the question is not what we are requested to join in thought to the given concept, but what we actually think together with and in it, though obscurely; and so it appears that the predicate belongs to these concepts necessarily indeed, yet not directly but indirectly by an added visualisation (Anschauung).
3. Metaphysical judgments, properly so called, are all synthetical.
Concepts and judgments pertaining to metaphysics may be analytical. These may not be metaphysical but can be combined to make a priori, synthetical, metaphysical judgments. For example, the analytical judgment "substance only exists as subject" can be used to make the judgment "all substance is permanent," which is a synthetical and properly metaphysical judgment.
§ 3. A remark on the general division of judgment into analytical and synthetical.
This division is critical but has not been properly recognized by previous philosophers.
§ 4. The general question of the Prolegomena: Is metaphysics at all possible?
The Critique of Pure Reason investigates this question synthetically. In it, an abstract examination of the concepts of the sources of pure reason results in knowledge of the actual science of metaphysics. The Prolegomena, on the other hand, starts with the known fact that there is actual synthetic a priori metaphysical knowledge of pure mathematics and pure natural science. From this knowledge, analytically, we arrive at the sources of the possibility of metaphysics.
§ 5. The general problem: How is knowledge from pure reason possible?
By using the analytical method, we start from the fact that there are actual synthetic a priori propositions and then inquire into the conditions of their possibility. In so doing, we learn the limits of pure reason.
Part one of the main transcendental problem. How is pure mathematics possible? § 6. Mathematics consists of synthetic a priori knowledge. How was it possible for human reason to produce such a priori knowledge? If we understand the origins of mathematics, we might know the basis of all knowledge that is not derived from experience.
§ 7. All mathematical knowledge consists of concepts that are derived from intuitions. These intuitions, however, are not based on experience.
§ 8. How is it possible to intuit anything a priori? How can the intuition of the object occur before the experience of the object?
§ 9. My intuition of an object can occur before I experience an object if my intuition contains only the mere form of sensory experience.
§ 10. We can intuit things a priori only through the mere form of sensuous intuition. In so doing, we can only know objects as they appear to us, not as they are in themselves, apart from our sensations. Mathematics is not an analysis of concepts. Mathematical concepts are constructed from a synthesis of intuitions. Geometry is based on the pure intuition of space. The arithmetical concept of number is constructed from the successive addition of units in time. Pure mechanics uses time to construct motion. Space and time are pure a priori intuitions. They are the mere forms of our sensations and exist in us prior to all of our intuitions of objects. Space and time are a priori knowledge of a sensed object as it appears to an observer.
§ 11. The problem of a priori intuition is solved. The pure a priori intuition of space and time is the basis of empirical a posteriori intuition. Synthetic a priori mathematical knowledge refers to empirically sensed objects. A priori intuition relates to the mere form of sensibility; it makes the appearance of objects possible. The a priori form of a phenomenal object is space and time. The a posteriori matter of a phenomenal object is sensation, which is not affected by pure, a priori intuition. The subjective a priori pure forms of sensation, namely space and time, are the basis of mathematics and of all of the objective a posteriori phenomena to which mathematics refers.
§ 12. The concept of pure, a priori intuition can be illustrated by geometrical congruence, the three–dimensionality of space, and the boundlessness of infinity. These cannot be shown or inferred from concepts. They can only be known through pure intuition. Pure mathematics is possible because we intuit space and time as the mere form of phenomena.
§ 13. The difference between similar things which are not congruent cannot be made intelligible by understanding and thinking about any concept. They can only be made intelligible by being intuited or perceived. For example, the difference of chirality is of this nature. So, also, is the difference seen in mirror images. Right hands and ears are similar to left hands and ears. They are not, however, congruent. These objects are not things as they are apart from their appearance. They are known only through sensuous intuition. The form of external sensible intuition is space. Time is the form of internal sense. Time and space are mere forms of our sense intuition and are not qualities of things in themselves apart from our sensuous intuition.
Remark I. Pure mathematics, including pure geometry, has objective reality when it refers to objects of sense. Pure mathematical propositions are not creations of imagination. They are necessarily valid of space and all of its phenomenal objects because a priori mathematical space is the foundational form of all a posteriori external appearance.
Remark II. Berkeleian Idealism denies the existence of things in themselves. The Critique of Pure Reason, however, asserts that it is uncertain whether or not external objects are given, and we can only know their existence as a mere appearance. Unlike Locke's view, space is also known as a mere appearance, not as a thing existing in itself."Descartes has demonstrated the subjectivity of the secondary qualities of perceptible objects, but Kant has also demonstrated that of the primary qualities." Schopenhauer, Manuscript Remains, I, § 716.