In the Groundwork for the Metaphysics of Morals, Kant begins his task by developing, through analysis of ordinary moral concepts, a theory of the 'supreme principle of morals,' the criteria for a higher faculty of desire (pure practical reason). The progression is from a good will to duty to the moral law, famously rendered as the formula of universal law, 'Act only according to the maxim...&c.' But, in the second section, Kant seems to begin this task anew, this time by beginning with practical reason and deriving from it the hypothetical and categorical imperatives (empirical and a priori practical syntheses), again discovering the moral law, this time in several different formulae.

My question is why does Kant need this repetition? Is he not simply saying the same thing twice, or rather, arriving at the same conclusion twice when just one path (ie the path of Section 2) would do the trick?

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    Is pure practical reason 'a higher faculty of desire' ? PPR is applied to our desires and inclination through the CI test. I don't feel comfortable in agreeing that PPR is itself a desire of any kind. It will be interesting to read any Comments on this point. That aside, the question is not without interest in its suggestion of 'arriving at the same conclusion twice'. – Geoffrey Thomas Jul 4 '18 at 5:49
  • I was vague in my wording there: pure practical reason legislates over a higher faculty of desire, or rather, the legislation of pure practical reason is the condition for the legitimate exercise of the higher faculty of desire (in the same way that the the legislation of the understanding is the condition of legitimate a priori synthesis in the higher faculty of knowledge). – WolandBarthes Jul 4 '18 at 13:00

The relation of Section II to Section I of the Groundwork is not obvious; and a question about it is quite in place. The topic is largely neglected.

Groundwork Part I

Section 1: Inducing the Desire for Philosophy

In purporting to show that the “supreme moral principle” is already present in “popular moral consciousness” —and hence may be recovered through philosophical analysis — section 1 of the Groundwork takes the reader through a series of related arguments. First, Kant claims that his readers already know that the only unconditionally good thing is a good will. They know that the good will is an incomparably higher good than all the ends we associate with happiness—“Power, riches, honor, even health”— and all the virtues to which the pagan philosophers aspired: “Moderation in affects and passions, self-control, and tranquil reflection” (AK, 4:393, 394; PP, pp. 49, 50). Next, Kant moves to elucidate this still somewhat esoteric conception of the good will by showing that it is already contained in the popular idea of doing one’s duty for its own sake (see AK, 4:397–400; PP, pp. 52–55). He then argues that his concept of duty must be understood as the determination of the will through the mere idea or thought (Vorstellung) of duty (see AK, 4:401–2; PP, pp. 56–57). Finally, Kant concludes that in constructing this conception of the moral principle he has done nothing more than clarify a principle already present in ordinary moral consciousness (see AK, 4:403–5; PP, pp. 58–60). (Ian Hunter, 'The Morals of Metaphysics: Kant’s Groundwork as Intellectual Paideia', Critical Inquiry , Vol. 28, No. 4 (Summer 2002), pp. 908-929: 914-5.)


Kant’s appeal to his students’ sense of “duty for its own sake” — formed no doubt in religious, military, and pedagogical institutions requiring unconditional obedience—is no simple elicitation of evidence for the moral law’s preexistence. In fact it is a means by which his students can be induced to subject themselves to the law as something that already commands them from within. The crucial thing to note in this regard is Kant’s initial characterization of duty: “We shall therefore take up the concept of duty, which contains that of a good will though under certain subjective limitations and hindrances, which, however, far from concealing it and making it unrecognisable, rather bring it out by contrast and make it shine more brightly” (AK, 4:397; PP, p. 52). Here Kant provides his students with a new way of relating to their (still unfocused) sense of duty. By treating its compulsive character as arising from the form in which a pure rational will encounters the “subjective limitations and hindrances” of their sensuous natures, Kant incites his students to view their ordinary sense of duty (no matter what its source) as if it were their dimly “sensed dependency” as material beings on the self-governing community of intelligences in which they participate as immaterial (rational) beings. (Hunter: 917.)

The 'form in which a pure rational will encounters the “subjective limitations and hindrances” of [our] sensuous natures' is that of a universal law to which as such we conform our actions.

Such a law is a categorical imperative and it is implicit in 'popular moral consciousness'. Section I thus draws out the idea of the categorical imperative from our ordinary moral thinking.

Groundwork Part II

Section II approaches the categorical imperative not from the side of ordinary moral thinking but from that of metaphysics or philosophical analysis. A purely rational will could only be a will that conforms its actions to universal law. Rationality and universality, the rational and the universally lawlike, are inseparably conjoined. And so Kant delivers the categorical imperative from a different angle - that of rationality as distinct from ordinary moral thinking.

He is also able later in Section II to formulate different but mutually entailing versions of the categorical imperative, a task not ventured in Section I.

Section 2: Teaching Transcendence

Having secured an audience disposed to view itself as the bearer of a pure but latent moral law, in section 2 of the Groundwork Kant shows how this law may be revealed, requiring his students to rise from “popular moral philosophy to the metaphysics of morals.” This transition takes the form of a series of arguments designed to “deduce” the moral law and to show the necessity of metaphysics for obtaining this insight.


Kant ... presents these arguments as if they were solving a philosophical problem, namely, the problem of showing how a categorical imperative is possible. We can show the possibility of technical imperatives (“imperatives of skill”)—the rules of geometry, for example—by demonstrating their analytic necessity for achieving a particular technical end, such as the construction of a mathematical figure (AK, 4:417; PP, p. 70). Further, we can show the possibility of prudential imperatives as the empirically necessary means to certain kinds of happiness; although here human disagreement over the ends of empirical happiness, and the uncertainty of their worldly attainment, means that prudential imperatives lack the unified and unconditional character of the moral law (see AK, 4:418–19; PP, pp. 70–71). How though, asks Kant, can we show the possibility of the moral law’s categorical imperative, given that this is by definition unconditional, hence independent of all empirical ends or goods capable of showing its necessity as a means?

This is the problem, Kant argues, whose solution hinges on the transition to metaphysics, which enables the philosopher to transcend the world of empirical ends and means and to propose a “solely a priori” solution. Given his conception of metaphysics, as the discipline permitting access to a domain where thinking natures act independently of all external empirical ends, Kant’s solution is to propose that the mere thought or concept of the categorical command might itself reveal its propositional content—and to this degree its possibility—independent of all need to relate this command to some empirical object or end: “In this task we want first to inquire whether the mere concept of a categorical imperative may not also provide its formula, containing the only proposition that can be a categorical imperative” (AK, 4:420; PP, pp. 72–73). The only proposition that can be a categorical imperative is, of course, “act only in accordance with that maxim through which you can at the same time will that it become a universal law” — because a universal law is the only one capable of commanding the will through the mere thinking of its idea, independent of all sensible ends and desires. (Hunter: 919-21.)


If this analysis is right, Kant does not 'begin [his] task anew' in Part II. Rather, if Part I is meant to persuade us from the side of ordinary moral thinking that we are all latent bearers of the moral will, through the idea of doing one's duty for its own sake, Part II reprises the idea that the categorical imperative involved in 'duty for its own sake' is also the principle of action of a purely rational will acting, unlike a possible God, under 'subjective limitations and hindrances'.


Why does Kant use more than one approach?

Kant is struggling with the subjectivity of morality. Given certain assumptions you can justify terrible and cruel behaviour, and corrupt any moral framework. The further dilemma is what works in biological relationship terms and what works rationally are two very different things.

Nihilism has been used to destroy biological affiliations and social affiliations and make innocent people worthy of death through a morality of group guilt, or power associated bias. So pliant is the human mind normal people from any school or street can be turned into sadistic exploiters of others in a few weeks given the right stimulus and motivations.

The discussion is probably not morality, but what socially people can get away with while appearing to conform to the social rules into which one is born. To a rationalist this probably appears too pliable, except looking at human civilisations, this is exactly what takes place. Kant appears to be trying to define something simple and refined, except this is probably impossible.

Just look at our own morality. If terrorists use no rules engagement, what do we do in response? If an army hide among civilians, do we stop killing innocents? If a war starts, how well do we prosecute murders by soldiers against non-combatants? If people are fleeing war and persecution, how well do we save their lives when it is in our power to do so?

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