Both Kant’s ethics and contemporary Kantian ethics have been criticized from many quarters. The critics evidently include those who advocate one or another form of teleological or consequentialist theory, who believe that it is possible to establish an account of the good, from which a convincing account of the right, and specifically of justice, can be derived. However, they also include a variety of writers who reject consequentialist thinking, including communitarians, virtue ethicists, Wittgensteinians and feminist thinkers (see Community and communitarianism; Virtue ethics; Wittgensteinian ethics; Feminist ethics).
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.
- Kant began his investigation into knowledge of perceived objects by considering indirect, reflective knowledge of concepts instead of direct, intuitive knowledge of perceptions.
- For Kant, there is absolutely no knowledge of an object unless there is thought which employs abstract concepts. For him, perception is not knowledge because it is not thought. In general, Kant claimed that perception is mere sensation.
Secondary errors
Transcendental analytic
- Kant asserted that metaphysics is knowledge a priori, or before experience. As a result, he concluded that the source of metaphysics cannot be inner or outer experience.
- Schopenhauer claimed that metaphysics must understand inner and outer experience in order to know the world and not empty forms. Kant did not prove that the material for knowing the world is outside of the experience of the world and merely in the forms of knowledge.
- Kant’s writing was obscure.
- Kant took the Greek word noumena, which meant “that which is thought,” and used it to mean “things-in-themselves.” (See Sextus Empiricus, Outlines of Pyrrhonism, Book I, Chapter 13: “Anaxagoras opposed what is thought (noumena) to what appears or is perceived (phenomena).”)
- Kant tried to create a logical, overly-symmetrical system without reflecting on its contents.
German philosopher Arthur Schopenhauer criticised Kant’s belief that ethics should concern what ought to be done, insisting that the scope of ethics should be to attempt to explain and interpret what actually happens. Whereas Kant presented an idealised version of what ought to be done in a perfect world, Schopenhaur argued that ethics should instead be practical and arrive at conclusions that could work in the real world, capable of being presented as a solution to the world’s problems.
Philosopher Friedrich Nietzsche criticised all contemporary moral systems, with a special focus on Christian and Kantian ethics. He argued that all modern ethical systems share two problematic characteristics: first, they make a metaphysical claim about the nature of humanity, which must be accepted for the system to have any normative force; and second, the system benefits the interests of certain people, often over those of others. Although Nietzsche’s primary objection is not that metaphysical claims about humanity are untenable (he also objected to ethical theories that do not make such claims), his two main targets—Kantianism and Christianity—do make metaphysical claims, which therefore feature prominently in Nietzsche’s criticism.