Watch this lecture from 28:26 to the end. Pay attention to the distinction Sandel draws between hypothetical and categorical imperatives, since this is what sets Kant apart from the utilitarian philosophers. Sandel breaks down some of the complexity of Kant's moral philosophy by illustrating the major contrasts Kant uses to develop it. While he gives three different versions of his categorical imperative, Kant considers it to be a singular rational principle for deciding how to act. As long as we follow the categorical imperative, we are acting out of duty, and we are respecting ourselves and others as rational beings.