In the Critique of Pure Reason, the Doctrine of Method plans out the scientific study of the principles of pure theoretical reason. Here, however, the Doctrine of Method will be instead a discussion of how the principles of practical reason can be brought to bear on real life. In other words, the Doctrine of Method concerns how we can make people moral.
We have seen that truly moral action requires not only an outward show of good behavior, but also the right mindset. A cynic might be doubtful as to whether acting out of duty is a real possibility for us. If so, even if we could produce a simulacrum of a moral society, it would all be hypocrisy, since everyone would secretly only pursue his or her own advantage. Furthermore, in this scenario, the outward show of morality itself would not be stable, but instead dependent on its continuing to be to the advantage of each individual. Fortunately, these doubts are misguided.
Whenever there is a social gathering, the conversation will include argumentation, as well as jokes and stories. One of the favorite forms of such argumentation crosses it with gossip, and concerns the moral quality of others' actions. Even people who normally do not enjoy intricate arguments will reason acutely and with great attention to detail when caught up with justification or condemnation of others.
Moral education can utilize this natural human tendency for moral evaluation by presenting the students with historical examples of good and bad actions. By debating the worth of these, the students will be given the opportunity to experience the admiration we feel for moral goodness and the disapproval we feel for moral badness.
We must select the right sorts of examples, though, to demonstrate moral goodness. We are liable to err in two ways. The first is to try to entice the students into being moral by examples where morality and self-love coincide. The second is to try to emotionally enthuse the students about morality with examples of exceptional heroism, above even what morality requires. Instead, our examples should stress sheer dutifulness.
The first of these methods is bound to fail because the students will not come to understand the unconditional nature of duty. Nor will the examples be very moving. When we see exceptional self-sacrifice for the sake of upholding a principle, we are inspired, amazed, and awed. When we see someone following a principle with little or no sacrifice, though, we are not impressed to nearly the same degree.
The second method will not work because it over-stimulates the emotions rather than appealing to reason. Only reason can produce a long-term change in a person's character. The second method also leads the students to regard moral goodness as an unattainable perfection relevant only to melodrama, and so to scorn the everyday obligations they should be fulfilling as boring and petty.
Kant closes the second Critique with a hopeful note on the future of ethics. The wonders of both the physical and ethical world are always not far for us to find—to feel awe, we have only to look upward to the stars or inward to the moral law in our hearts. The study of the physical world languished for a long time in superstition before the physical sciences began. We can hope that the moral sciences will similarly replace superstition about ethics.
The parallelism between the Doctrine of Method in the first and second Critique is somewhat forced, and we might wonder whether anything is gained from it. The Doctrine of Method and Conclusion are, along with the Preface, the most easily readable parts of the second Critique. Therefore, perhaps the Doctrine of Method not only discusses instruction, but, by closing the book on a strong note, it also serves the purpose of instruction. At any rate, we might wonder whether giving this section the same title as the Doctrine of Method of the first Critique was helpful.
One way in which the parallelism breaks down is that the Doctrine of Method in the first Critique lays out what is meant to be all possible sciences of pure theoretical reason, but all methods of moral education are not laid out in the second Critique's Doctrine of Method. Instead, only one method of moral education is offered. Nor are enough alternatives explored to make any convincing claim, even, that the method here is the best method.
Perhaps the reason that Kant does not discuss other possibilities for moral education is that he does not see any. The only alternative he discusses to his method of case-by-case argumentation is reward and punishment, which is rejected as producing only a simulacrum of moral goodness. Kant pays no attention to the methods that rely on looking at and acting in real-life examples—methods that parents often use long before Kant's method is feasible. So, one might point out features of a situation—"Billy won't share his toys with Susie, and now she's crying. That wasn't nice of him."—instruct—"Be a good girl and give Susie your teddy bear."—and explain—"See how happy Susie looks now? It's good to share your things with others."
Possibly these methods are left out because they do not fall neatly on either side of the divide between leveling brute commands on the one hand and engaging in a reasoned theoretical discussion on the other. One might likewise think that involvement in real-life cases is helpful while learning the meaning of right and wrong, but that once one understands these ideas, purely theoretical argumentation is best for motivating us to care about these ideas. This might be so, but it cannot be assumed.
Although the moral world (as well as the starry heavens) continues to make people stand in awe today just as it did in Kant's day, Kant's hopes for a scientific morality do not appear to have been fulfilled. There are some people, mostly in academia, who accept Kant's ethical system, and many more who accept some parts of it. But there has not been any firm consensus in favor of his system, nor in favor of any competing ethical system. There have been shifts in moral attitudes over the two hundred or so years since Kant's death in 1804, for example, most people today consider it suitable for women to manage their own lives, whereas most people in 1804 considered it suitable for women's lives to be managed by a father, brother, or husband. However, despite the shifts in what the average person believes about ethics, there is still at least an equal variety of disagreement around this average. Nor have the shifts in ethical views come about by anything like the scientific method, much less the sort of a priori method of geometry Kant uses in the Analytic of the second Critique. If scientific resolution of our ethical debates is fated, it must be still to come.