Kant defines freedom as the ability to give yourself your own law. Whenever we obey the demands of physical needs, desires, or circumstances, or whenever we make a decision that considers the probable consequences of our action, we receive our motivation from something other than ourselves, and we are not free according to Kant's definition. Freedom, he argues, is possible only in a condition of "autonomy"—that is, of depending only on reason for our motives and principles.

The categorical imperative is Kant's litmus test for determining whether our moral principles conform to reason. Thus, according to Kant, we are free only if we obey the categorical imperative. This account of freedom makes sense within Kant's system of concepts, but it seems to exclude certain possibilities. Kant argues that we are in a state of "heteronomy" (and therefore not free) whenever we follow some impulse that does not come from reason. Yet if we are genuinely free, then we should be able to choose options other than reason.

Popular pages: Grounding for the Metaphysics of Morals