Autonomy and the kingdom of ends
To be rational is, formally speaking, to act on your representation of a law, whatever that law might be; but we have now seen that the content or material of the maxims or laws on which we act is given by the value we necessarily set upon our own humanity or rational nature. Putting these two ideas together leads us to a third idea, which is that as rational beings we make the law, we legislate it, for ourselves and each other. Suppose, for instance, I undertake a program of scientific research. I am curious, and wish to know; in treating my curiosity as a reason to undertake the research, I am in effect taking it to be good that I should know. Furthermore, since we have a duty to pursue one another’s ends, my decision to pursue scientific research involves a claim on others: that they should recognize the value of my pursuit of this end, should not hinder it, and perhaps, under certain conditions, even offer help with it when I am in need. Thus my choice is an act of legislation: I lay it down, for myself and all others, that this research is a good thing, and shall be pursued. We may say that I confer a value upon scientific research, when I choose to pursue it. At the same time, however, the very fact that I make this claim on others whose humanity must be respected serves as a “limiting condition” on my own choice (4:431). If the end that I choose, or the means by which I choose to pursue it, is inconsistent with the value of humanity, then I cannot legislate it, and my choice is null and void: my maxim is not a law. Pulling these ideas together leads to what Kant describes as “the principle of every human will as a will universally legislating through all its maxims” (4:432).
This principle, Kant tells us, “would be very well fitted to be the categorical imperative” (4:432), because it suggests that the reason we are bound to obey the laws of morality is that we legislate these laws ourselves, that they are our own laws. According to Kant there are two ways in which we may be bound to conform to a law. Sometimes, we conform to a law because of some interest we have that is served by such conformity – for instance, when the law is supported by a sanction. If disobedience to the law will lead to our being fined, socially ostracized, thrown into prison, or dispatched to hell; or if obedience means we will be loved, saved, rewarded, or well-pleasing to God, we may consider ourselves bound to obey it for those reasons. At other times, however, we regard ourselves as bound to obey a law because we endorse the law itself, considered as a law: we think that this is indeed how people in general ought to act, and so we act that way ourselves. Kant calls the first sort of motivation heteronomous, because we are bound to the law by something outside of ourselves – God, the state, or nature – that attaches the sanction to the law. The second kind of motivation is autonomous, because we bind ourselves to the law. The principle that we give universal law through our maxims suggests that moral motivation is autonomous.10
And on reflection it seems that moral motivation must be autonomous. For if we are motivated to obey a law heteronomously, by a sanction, then the imperative we follow in obeying that law is a hypothetical imperative: if you would stay out of prison, or go to heaven, or whatever, then you must obey this law. And in that case, of course, the requirement is not unconditional after all. If categorical imperatives exist, then, it must also be true that human beings are capable of autonomous motivation. There can be only one reason why we must do what duty demands, and that is that we demand it of ourselves.
Earlier we saw that according to Kant’s Copernican Revolution, the laws of reason are not something we find in the world, but rather something we human beings impose upon the world. We have now come around to the practical expression of that idea. Kant’s predecessors, he believes, failed to discover the principle of morality, because they looked outside of the human will for the source of obligation, whereas obligation arises from, and so can only be traced to, the human capacity for self-government. Morality, on Kant’s conception, is a kind of metaphysics in practice. We ourselves impose the laws of reason on our actions, and through our actions, on the world, when we act morally.
The principle of autonomy provides us with a third way of formulating the moral law: we should so act that we may think of ourselves as legislating universal laws through our maxims.11 When we follow this principle we conceive ourselves as legislative citizens in the kingdom of ends. The kingdom of ends may be conceived either as a kind of democratic republic, “the systematic union of several rational beings through common laws” which the citizens make themselves; or as a system of all good ends, “a whole of all ends (of rational beings as ends in themselves, as well as the ends of its own that each of them may set for itself)” (4:433). The laws of the kingdom of ends are the laws of freedom, both because it is the mark of free citizens to make their own laws, and because the content of those laws directs us to respect each citizen’s free use of his or her own reason. The conception of ourselves as legislative citizens is the source of the dignity we accord to human beings, a dignity which Kant, bringing the argument full circle, now equates with the unconditional value of a good will. We now know what gives the good will its unconditional value:
It is nothing less than the share it obtains for a rational being in universal legislation, by which it makes it fit to be a member of a possible kingdom of ends. (4:435)
But we also now know what we need to do in order to complete the argument. Recall that morality is real if the moral law has authority for our wills. The argument of the second section has yet not shown this, but it has prepared the way, for we now know what has to be true of us if the moral law is to have authority for our wills. We must be autonomous beings, capable of being motivated by the conception of ourselves as legislative citizens in the kingdom of ends, citizens who are bound only by the laws that we give to ourselves. If Kant can show that we are autonomous, he will have shown that we are obligated by the moral law. This is the project of the third section.