The person who most completely lives as an autonomous person, then, is the one for whom the disposition to follow the Categorical Imperative is most effective. That is, he not only conforms to the principles that he freely adopted but does so because they are principles that he freely and rationally adopted. This is the person most completely "self-governing."
Why, then, did Kant hold conscientious adherence to the Categorical Imperative in such high regard? It was, I suggest, to a large extent because he felt that the noblest feature of humanity is the capacity to be self-governing, to adopt principles without being influenced by sensuous motives and then to live by them whatever the contingencies. On Kant's theory, the man who best realizes this capacity is the man who acts from respect for the Categorical Imperative.
I conclude with two brief comments. First, if my explanation of the importance of moral conduct is correct, then Kant should not be viewed as a man obsessed with duty for duty's sake. He believed, of course, that one ought always to do one's duty and also that only acts motivated by respect for moral law have moral worth. What is uniquely important to Kant about moral conduct, however, is not its difficulty, orderliness, or purposelessness; it is rather the fact that moral conduct is the practical exercise of the noble capacity to be rational and self-governing, a capacity which sets us apart from the lower animals and gives us dignity. Kant's ethics is as much an ethics of self-esteem as it is an ethics of duty.
Finally, without overlooking the important differences between the Categorical Imperative and the Hypothetical Imperative, we may note a further similarity. Both principles, as it turns out, enjoin a person to follow through on what he himself wills. The Hypothetical Imperative tells him not to balk at the necessary means to the ends he wills, and the commands of the Categorical Imperative are simply the constraints he himself adopts as a rational and autonomous person. To put the point paradoxically, we could summarize the demands of practical reason by saying, "Do what you will."
(Thomas E. Hill Jr, "The Hypothetical Imperative," The Philosophical Review 82 [October 1973]: 429-50, at 449-50 [italics in original; footnote omitted])
Note from KBJ: Two things. First, notice the difference between "Do what you want" and "Do what you will." Second, notice that Kant, the deontologist, like John Stuart Mill, the consequentialist, distinguishes between the rightness of the act itself and the goodness or worthiness of the motive from which the act springs. To both philosophers, one can do the right thing for the wrong reason (as well as the wrong thing for the right reason). Kant divides right acts into two categories: (1) those motivated solely by duty and (2) those motivated by something other than, or in addition to, duty. Only acts in category 1 are morally worthy. For Kant, then, worthy acts are (given human fallibility) a proper subset of right acts. (All of God's acts are worthy as well as right.) President Bush's invasion of Iraq could have been right (i.e., in accordance with duty) but not worthy (i.e., not from duty). His motive for invading is literally irrelevant to the rightness of what he did—for both Kant and Mill. Unfortunately, almost all of the criticism of the invasion by progressives was based on President Bush's motives (or worse, alleged motives). This was frustrating for me, as a moral philosopher. I wanted a national debate on the rightness of the invasion. I don't give a damn about President Bush's motives. Who knows his motives, anyway, besides him? Maybe even he doesn't know his motives.