Immanuel kant is considered the father of duty-oriented theory. what principle underlies kant's theory?

The principle of Kant's theory is "The correct action is based on a determined principle independently of the result". Kant's theory is a theory of Ethics, he considers that a person is good if their actions it is based on a moral law. For example, if someone is helped, the reason must be disinterested so that it is good, if it helps someone for their own benefit, it is not considered a good action.