Kant conceived his three Critiques to be the core of his oeuvre, each work exploring a different power of the mind: The Critique of Pure Reason setting forth the limits and capacities of the theoretical employment of Reason; the Critique of Practical Reason examining the use of the power of reason in action; and the curious Critique of Judgment dealing both with the role of Judgment in the making of aesthetic judgments and its role in the offering of teleological explanations in science.
We might naturally suppose that the Second Critique, of Practical Reason, would be the locus classicus for Kant's teachings in the field of Ethics. In fact, as it turns out, that is not true. Kant wrote three major works devoted to normative subjects: The Groundwork of the Metaphysics of Morals, published in 1785; the Critique of Practical Reason, published in 1790, and the Metaphysics of Morals, published in 1797. It is actually the first of these works, the relatively brief Grundlegung [or "Groundwork"] that is universally considered far and away the most important of Kant's writings on the subject of Ethics.
Fully to explicate the Groundwork would require a book -- which I have written. [See The Autonomy of Reason, Harper Torchbooks, 1973.] I can only hope in this tutorial to lay out the structure of the work, explain the most essential elements of the argument, discuss at the end of the tutorial certain very deep and intractable problems with Kant's account, and then spend a bit of time recounting how I think Kant has a possible answer to one of the major difficulties, not in the text before us, but in the last of his major writings on Ethics, the Metaphysics of Morals. That will most certainly be more than enough to fill a tutorial of manageable length.
While I am marking time until I get to Paris and retrieve my copy of the Groundwork, perhaps I can say a few words about an important logical matter that Kant borrowed from Jean-Jacques Rousseau, whose writings had a very powerful effect on the great German philosopher. [Kant led a very quiet life, unlike Rousseau, and only a handful of stories about him have survived. One concerns his habit of taking a daily walk with his servant, Lampe, at precisely the same time each day -- a habit so regular that the townspeople of Kőnigsberg, it is said, set their clocks by him. It seems that on the day when a copy of Rousseau's new book, Ḗmile, arrived, Kant became so engrossed in it that he missed his walk. I am afraid that had he lived a century and a half later, Kant would have been classified as possessing an anal retentive obsessive compulsive personality.]
[One more irrelevant story, inasmuch as I am just vamping 'til ready, as they say in the jazz world. When I arrived at Oxford University in early Fall, 1954, I went off to see T. D. Weldon, whose book on the First Critique I had read and admired greatly. He turned out to be rather like the Caterpillar in Alice in Wonderland, sitting on a chair that looked rather like an overstuffed mushroom. He was not smoking a Hookah, but was pretty clearly inebriated. I told him, with the innocent enthusiasm of a twenty-year old, that I wanted to take the Critique and re-read it with Kemp Smith's commentary in one hand and Paton's in the other. He looked rather bored and said that was very old hat. -- he did not add, "old boy," as I recall, but he might have. No, he told me, what I must do if I was interested in Kant was to read Rousseau's Ḗmile. I rushed right out and bought a copy, but when I started to read it, I found that the first fifty pages were an impassioned defense of breast feeding and a diatribe against swaddling. I gave it up, and I think never actually finished the book.]
In Of the Social Contract [the actual title -- du contrat social], Rousseau grounds his argument on a distinction between a General Will and a Particular Will. All political willing, he says, is general in its logical structure, issuing in laws, not in commands. But an individual elector may, in his willing [never a woman, of course], aim either at his individual and personal good, or at the General Good. If an individual chooses dictates having the logical structure of laws and aimed at the General good, then he may be said to have a General Will. If an entire society does this, with each person aiming at the General Good, then the society as a whole may be said to have a General Will. [I go into this simple point at length in order to disabuse you of the incorrect idea that the General Will in Rousseau's writings is some sort of transcendent or non-natural thing.]
Kant, as we shall see, accepts Rousseau's claim that laws are by the nature general or universal in their logical structure. Kant thinks that he can derive a powerful, albeit analytic, proposition about willing, namely that, roughly speaking, if a reason for the adoption of a law is a good reason for me, then it must be an equally good reason for any rational agent similarly circumstanced. It is from this argument that he eventually derives the first formulation of the Highest Moral Law, viz. "I ought never to act except in such a way that I can will that my maxim should become a universal law."
But this, not surprisingly, turns out to be a merely negative or necessary condition for the objectivity or moral bindingness of a moral law. There remains the question what the end, or goal, or -- in Kant's way of talking -- the matter of the proposed law is. That is to say, at what end does this proposed law aim in its universally binding fashion? And this is where all the trouble arises. Kant has such difficulty answering this question that in the brief compass of the Groundwork he addresses it three separate times. As we shall, see, well down the road in this tutorial, it is in his efforts to answer this crucial question of the objective and necessary end or goal of rational willing that Kant's theory comes into an interesting conjunction with the much later work of John Rawls.
But this is nothing more than a preview of coming attractions, so if you will all buy your popcorn or nachos or Goobers [my personal choice in movie theaters], we shall adjourn this tutorial until I get to Paris.