Immanuel Kant was a German philosopher born in 1724 who developed the deontological ethical theory of Kantianism. Some of Kant's most important concepts included the categorical imperative which holds that moral actions are those done from duty in accordance with universal moral rules. For an action to have moral worth, it must be done from duty rather than inclination. Kant also believed that humans have free will and are ends in themselves, never to be used solely as a means to another end.