Prolegomena to Any Future Metaphysics That Will Be Able to Present Itself as a Science (German: Prolegomena zu einer jeden künftigen Metaphysik, die als Wissenschaft wird auftreten können) is a book by the German philosopher Immanuel Kant, published in 1783, two years after the first edition of his Critique of Pure Reason.

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.

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.

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.

His result allowed him to determine the bounds of pure reason and to answer the question regarding the possibility of metaphysics as a science.

In it, an abstract examination of the concepts of the sources of pure reason results in knowledge of the actual science of metaphysics.

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.

The concept of pure, a priori intuition can be illustrated by geometrical congruence, the three–dimensionality of space, and the boundlessness of infinity.

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.

The difference between truth and dreaming or illusion depends on the connection of representations according to rules of true experience.

The first physical principle of pure understanding subsumes all spatial and temporal phenomenal appearances under the concept of quantity.

The principles of the analogies of experience state that perceptual appearances, not things in themselves, are thought of as experienced objects, in accordance with a priori rules of the understanding.

The concept of causality refers to thoughts and statements about the way that successive appearances and perceptions are universally and necessarily experienced as objects, in any consciousness.

The principles that contain the reference of the pure concepts of the understanding to the sensed world can only be used to think or speak of experienced objects, not things in themselves.

The constitution of our five senses and the way that they provide data makes nature possible materially, as a totality of appearances in space and time.

The constitution of our understanding makes nature possible formally, as a totality of rules that regulate appearances in order for them to be thought of as connected in experience.

According to natural law, gravitation decreases inversely as the square of the surfaces, over which this force spreads, increases.

In the third antinomy, the contradiction is resolved if we realize that natural necessity is a property of things only as mere appearances, while freedom is attributed to things–in–themselves.

This exposition of the antinomy will allow the reader to combat the dialectical illusions that result from the nature of pure reason.

All questions about them must be answerable because they are only principles that reason has originated from itself in order to achieve complete and unified understanding of experience.

In order to strengthen morality, reason has a tendency to be unsatisfied with physical explanations that relate only to nature and the sensible world.

In order for metaphysics to become a science, a critique of pure reason must systematically investigate the role of a priori concepts in understanding.

Kant was motivated to write this Prolegomena after reading what he judged to be a shallow and ignorant review of his Critique of Pure Reason.

Among other mistakes, the review claimed that Kant's table and deduction of the categories were "common well–known axioms of logic and ontology, expressed in an idealistic manner."

Any future metaphysics that claims to be a science must account for the existence of synthetic a priori propositions and the dialectical antinomies of pure reason.

If the Critique and the Prolegomena are studied and revised by a united effort by thinking people, then metaphysics may finally become scientific.

Lewis White Beck claimed that the chief interest of the Prolegomena to the student of philosophy is "the way in which it goes beyond and against the views of contemporary positivism".

"[6] Ernst Cassirer asserted that "the Prolegomena inaugurates a new form of truly philosophical popularity, unrivaled for clarity and keenness".

[7] Schopenhauer, in 1819, declared that the Prolegomena was "the finest and most comprehensible of Kant's principal works, which is far too little read, for it immensely facilitates the study of his philosophy".