His ideas are influential even today. Kant looked at old philosophical problems in new ways. For example, we don't derive our notions of space and time from sense experience. Instead, we impose these structures on our sensations. The mind is active.
Ethics works the same way.
Reason imposes its own abstract, formal laws on our actions. Morality ultimately rests, not on sense experience or feelings, but on reason. These summaries and problems deal with Kant's Groundwork of the Metaphysic of Morals. The Groundwork Kant's Groundwork defends morality against those who reduce it to self-interest, feelings, or empirical fact. Instead, the supreme moral principle is based on pure reason.