Critique of Practical Reason

Kant begins by distinguishing between two kinds of principles by which people decide how to behave. The first are maxims, which are “subjective” rules applied to specific circumstances. The second category is that of laws, which are universal and objective rules determined through reason. People use their own reason constantly to distinguish between laws and maxims in their daily lives. Kant gives the example of someone who believes they should seek revenge on anyone who insults them. Even such a person understands that “this is no practical law but only his maxim” (17). Each individual’s actions are shaped by that person’s free will as it reasons between maxims and laws. People are also motivated by imperatives, which Kant defines as rules “indicated by an ‘ought’” (18). However, many imperatives can be subjective because they are conditional and are motivated by a specific goal or object. For example, the imperative that someone “must work and save in his youth in order not to want in his old age” (18) is conditioned on whether that person actually wants to grow old or anticipates some other form of support later in life. Kant labels imperatives that are universal and not at all conditional, such as that one should not knowingly make false promises, as “categorical imperatives” (18-19).