Source: Stanford encyclopaedia

At the heart of Kant’s moral theory is the position that rational human wills are autonomous. Kant saw this as the key to understanding and justifying the authority moral requirements have over us. As with Rousseau, whose views influenced Kant, freedom does not consist in being bound by no law, but by laws that are in some sense of one’s own making. The idea of freedom as autonomy thus goes beyond the merely ‘negative’ sense of being free from influences on our conduct originating outside of ourselves. It contains first and foremost the idea of laws made and laid down by oneself, and, in virtue of this, laws that have decisive authority over oneself.

Kant’s basic idea can be grasped intuitively by analogy with the idea of political freedom as autonomy (See Reath 1994). Consider how political freedom in liberal theories is thought to be related to legitimate political authority: A state is free when its citizens are bound only by laws in some sense of their own making — created and put into effect, say, by vote or by elected representatives. The laws of that state then express the will of the citizens who are bound by them. The idea, then, is that the source of legitimate political authority is not external to its citizens, but internal to them, internal to ‘the will of the people’. It is because the body politic created and enacted these laws for itself that it can be bound by them. An autonomous state is thus one in which the authority of its laws is in the will of the people in that state, rather than in the will of a people external to that state, as when one state imposes laws on another during occupation or colonization. In the latter case, the laws have no legitimate authority over those citizens.

In a similar fashion, we may think of a person as free when bound only by her own will and not by the will of another. Her actions then express her own will and not the will of someone or something else. The authority of the principles binding her will is then also not external to her will. It comes from the fact that she willed them. So autonomy, when applied to an individual, ensures that the source of the authority of the principles that bind her is in her own will. Kant’s view can be seen as the view that the moral law is just such a principle. Hence, the ‘moral legitimacy’ of the CI is grounded in its being an expression of each person’s own rational will. It is because each person’s own reason is the legislator and executor of the moral law that it is authoritative for her.

Kant argues that the idea of an autonomous will emerges from a consideration of the idea of a will that is free “in a negative sense”. The concept of a rational will is of a will that operates by responding to reasons. This is, firstly, the concept of a will that does not operate through the influence of factors outside of this responsiveness to reasons. For a will to be free is thus for it to be physically and psychologically unforced in its operation. Hence, choices made because of obsessions or thought disorders are not free in this negative sense. But also, for Kant, a will that operates by being determined through the operation of natural laws, such as those of biology or psychology, cannot be thought of as operating by responding to reasons. Hence, determination by natural laws is conceptually incompatible with being free in a negative sense.

A crucial move in Kant’s argument is his claim that a rational will cannot act except “under the Idea” of its own freedom (4:448). The expression ‘acting under the Idea of freedom’ is easy to misunderstand. It does not mean that a rational will must believe it is free, since determinists are as free as libertarians in Kant’s view. Indeed, Kant goes out of his way in his most famous work, the Critique of Pure Reason, to argue that we have no rational basis for believing our wills to be free. This would involve, he argues, attributing a property to our wills that they would have to have as ‘things in themselves’ apart from the causally determined world of appearances. Of such things, he insists, we can have no knowledge. For much the same reason, Kant is not claiming that a rational will cannot operate without feeling free. Feelings, even the feeling of operating freely or the ‘looseness’ Hume refers to when we act, cannot be used in an a priori argument to establish the CI, since they are empirical data.

One helpful way to understand acting ‘under the Idea of freedom’ is by analogy with acting ‘under the Idea’ that there are purposes in nature: Although there is, according to Kant, no rational basis for the belief that the natural world is (or is not) arranged according to some purpose by a Designer, the actual practices of science often require looking for the purpose of this or that chemical, organ, creature, environment, and so on. Thus, one engages in these natural sciences by searching for purposes in nature. Yet when an evolutionary biologist, for instance, looks for the purpose of some organ in some creature, she does not after all thereby believe that the creature was designed that way, for instance, by a Deity. Nor is she having some feeling of ‘designedness’ in the creature. To say that she ‘acts under the Idea of’ design is to say something about the practice of biology: Practicing biology involves searching for the purposes of the parts of living organisms. In much the same way, although there is no rational justification for the belief that our wills are (or are not) free, the actual practice of practical deliberation and decision consists of a search for the right casual chain of which to be the origin — consists, that is, seeking to be the first causes of things, wholly and completely through the exercise of one’s own will.

Kant’s says that a will that cannot exercise itself except under the Idea of its freedom is free from a practical point of view (im practischer Absicht). In saying such wills are free from a practical point of view, he is saying that in engaging in practical endeavors — trying to decide what to do, what to hold oneself and others responsible for, and so on — one is justified in holding oneself to all of the principles to which one would be justified in holding wills that are autonomous free wills. Thus, once we have established the set of prescriptions, rules, laws and directives that would bind an autonomous free will, we then hold ourselves to this very same of set prescriptions, rules, laws and directives. And one is justified in this because rational agency can only operate by seeking to be the first cause of its actions, and these are the prescriptions, and so on, of being a first cause of action. Therefore, rational agents are free in a negative sense insofar as any practical matter is at issue.

Crucially, rational wills that are negatively free must be autonomous, or so Kant argues. This is because the will is a kind of cause — willing causes action. Kant took from Hume the idea that causation implies universal regularities: if x causes y, then there is some universally valid law connecting Xs to Ys. So, if my will is the cause of my φing, then Φing is connected to the sort of willing I engage in by some universal law. But it can’t be a natural law, such as a psychological, physical, chemical or biological law. These laws, which Kant thought were universal too, govern the movements of my body, the workings of my brain and nervous system and the operation of my environment and its effects on me as a material being. But they cannot be the laws governing the operation of my will; that, Kant already argued, is inconsistent the freedom of my will in a negative sense. So, the will operates according to a universal law, though not one authored by nature, but one of which I am the origin or author. And that is to say that, in viewing my willing to φ as a negatively free cause of my φing, I must view will as the autonomous cause of my having φed, as causing my having φed by way of some law that I, insofar as I am a rational will, laid down for my will.

Thus, Kant argues, a rational will, insofar as it is rational, is a will conforming itself to those laws valid for any rational will. Addressed to imperfectly rational wills, such as our own, this becomes an imperative: ‘Conform your action to a universal non-natural law’. Kant assumed that there was some connection between this formal requirement and the formulation of the CI which enjoins us to ‘Act as though the maxim of your action were to become by your will a universal law of nature’. But, as commentators have long noticed (see, e.g., Hill, 1992), it is not clear what the link is between the claim that rational autonomous wills conform themselves to whatever universally valid laws require, and the more substantial and controversial claim that you should evaluate your maxims in the ways implied by the universal law of nature formulation.

Further: an article by Stephen Darwall gives an in depth account of autonomy.