From the Greek hetero ('different') and nomos ('law').
Heteronomy is the principle which implies that individuals are not capable of self-rule.
In moral and political theory 'heteronomy' implies that individuals need some external authority to inform them of their moral/political obligations; we are incapable of coming to know our obligations on our own.
Kant explicitly opposes this claim by arguing that because of our capacity for reason, persons are innately autonomous. Thus, any moral agent will be, by nature, capable of recognizing and understanding their moral obligations. He states this in the third articulation of the Categorical Imperative: The will of every moral agent can be understood to be a legislature unto itself (Kant, Groundwork for the Metaphysic of Morals, Section 2).