"Critique of the Kantian philosophy" (German: "Kritik der Kantischen Philosophie") is a criticism Arthur Schopenhauer appended to the first volume of his The World as Will and Representation (1818). He wanted to show Immanuel Kant's errors so that Kant's merits would be appreciated and his achievements furthered. At the time he wrote his criticism, Schopenhauer was acquainted only with the second (1787) edition of Kant's Critique of Pure Reason. When he later read the first (1781) edition, he said that many of Kant's contradictions were not evident.

Kant's merits

According to Schopenhauer's essay, Kant's three main merits are as follows: Schopenhauer also said that Kant's discussion, on pages A534 to A550, of the contrast between empirical and intelligible characters is one of Kant's most profound ideas. Schopenhauer asserted that it is among the most admirable things ever said by a human.

Kant's faults

Fundamental error

Perceptions and concepts

Kant wanted to make the table of judgments the key to all knowledge. In so doing, he was concerned with making a system and did not think of defining terms such as perception and conception, as well as reason, understanding, subject, object, and others. Fundamental error: Kant did not distinguish between the concrete, intuitive, perceptual knowledge of objects and the abstract, discursive, conceptual, knowledge of thoughts.

Secondary errors

Transcendental analytic

Concepts

Idealism

Object-in-itself and thing-in-itself

According to Schopenhauer, there is a difference between an object-in-itself and a thing-in-itself. There is no object-in-itself. An object is always an object for a subject. An object is really a representation of an object. On the other hand, a thing-in-itself, for Kant, is completely unknown. It cannot be spoken of at all without employing categories (pure concepts of the understanding). A thing-in-itself is that which appears to an observer when the observer experiences a representation.

Schemata

Judgments/categories

Transcendental dialectic

Reason

Ideas of reason

Ethics

Categorical Imperative

Power of judgment

Aesthetics

Teleology

Reactions to Schopenhauer

Paul Guyer

In The Cambridge Companion to Schopenhauer (1999), the philosopher Paul Guyer wrote an article titled "Schopenhauer, Kant, and the Methods of Philosophy." In it, he compared the methods of the two philosophers and in so doing, discussed Schopenhauer's Criticism. In explaining how objects are experienced, Kant used transcendental arguments. He tried to prove and explain the fundamental principles of knowledge. In so doing, he started by indirectly conceptually reflecting on the conditions that exist in the observing subject that make possible verbal judgments about objective experience. In contrast, Schopenhauer's method was to start by a direct examination of perceived objects in experience, not of abstract concepts. The fundamental principles of knowledge cannot be transcendentally explained or proved, they can only be immediately, directly known. Such principles are, for example, the permanence of substance, the law of causality, and the mutual interactive relationships between all objects in space. Abstract concepts, for Schopenhauer, are not the starting point of knowledge. They are derived from perceptions, which are the source of all knowledge of the objective world. The world is experienced in two ways: (1.) mental representations that involve space, time, and causality; (2.) our will which is known to control our body. Guyer stated that Schopenhauer raised important questions regarding the possibility of Kant's transcendental arguments and proofs. However, even though Schopenhauer objected to Kant's method, he accepted many of Kant's conclusions. For example, Kant's description of experience and its relation to space, time, and causality was accepted. Also, the distinction between logical and real relations, as well as the difference between phenomena and things-in-themselves, played an important role in Schopenhauer's philosophy. In general, the article tries to show how Schopenhauer misunderstood Kant as a result of the disparity between their methods. Where Kant was analyzing the conceptual conditions that resulted in the making of verbal judgments, Schopenhauer was phenomenologically scrutinizing intuitive experience. In one case, though, it is claimed that Schopenhauer raised a very important criticism: his objection to Kant's assertion that a particular event can be known as being successive only if its particular cause is known. Otherwise, almost all of Schopenhauer's criticisms are attributed to his opposite way of philosophizing which starts with the examination of perceptions instead of concepts.

Derek Parfit

In philosopher Derek Parfit's 2011 book On What Matters, Volume 1, Parfit presents an argument against psychological egoism that centers around an apparent equivocation between different senses of the word "want":

Michael Kelly

Michael Kelly, in the preface to his 1910 book Kant's Ethics and Schopenhauer's Criticism, stated: "Of Kant it may be said that what is good and true in his philosophy would have been buried with him, were it not for Schopenhauer...."

Immanuel Kant

Immanuel Kant himself predicted a response to Schopenhauer's argument that he redundantly repeated the ancient command: "don't do to another what you don't want done to you", that is, the Golden Rule, and famously criticized it for not being sensitive to differences of situation, noting that a prisoner duly convicted of a crime could appeal to the golden rule while asking the judge to release him, pointing out that the judge would not want anyone else to send him to prison, so he should not do so to others. Kant's Categorical Imperative, introduced in Groundwork of the Metaphysic of Morals, is often confused with the Golden Rule. Also, it is exactly for being cold and dead because it is to be followed without love, feeling, or inclination, but merely out of a sense of duty, both in the theory and in its practice, that the Categorical Imperative is absolute, metaphysical and moral.