Introduction

In §40 of TJ, Rawls tells us that “there is a Kantian interpretation” of justice as fairness “based upon Kant's notion of autonomy” (TJR, p. 221), and goes on to say:

Likewise one of Rawls's aims in “Kantian Constructivism in Moral Theory” is “to set out the Kantian roots” of justice as fairness by showing how it incorporates “the distinctive features of Kantian constructivism” (CP, p. 303). Those features he summarizes as follows:

This is to say that Kantian constructivism deploys a Kantian conception of the person as free and equal agents with different rational and moral capacities, and that this conception of the person is the basis of a deliberative procedure incorporating different requirements of practical reason that is used to justify a set of normative principles. In justice as fairness, of course, the deliberative procedure is the rational choice in the original position. Furthermore, within a constructivist theory the standard of correctness for a set of normative principles is that they result from the employment of this procedure. In PL, where Rawls sees the need to develop justice as fairness as a political conception of justice, he pulls back from its Kantian lineage to present it as a free-standing political view that does not presuppose any comprehensive moral doctrine. Here he stresses the contrasts between political constructivism and both Kant's moral constructivism and intuitionist moral realism. Still, the structural parallels between justice as fairness as a form of political constructivism and Kant's moral constructivism remain.

Two things fill the mind with ever new and increasing admiration and reverence, the more often and more steadily one reflects on them: the starry heavens above me and the moral law within me. I do not need to search for them and merely conjecture them as though they were veiled in obscurity or in the transcendent regionv beyond my horizon; I see them before me and connect them immediately with the consciousness of my existence. The first begins from the place I occupy in the external world of sense and extends the connection in which I stand into an unbounded magnitude with worlds upon worlds and systems of systems, and moreover into the unbounded times of their periodic motion, their beginning and their duration. The second begins from my invisible self, my personality, and presents me in a world which has true infinity but which can be discovered only by the understanding, and I cognize that my connection with that world (and thereby with all those visible worlds as well) is not merely contingent, as in the first case, but universal and necessary. The first view of a countless multitude of worlds annihilates, as it were, my importance as an animal creature, which after it has been for a short time provided with vital force (one knows not how) must give back to the planet (a mere speck in the universe) the matter from which it came. The second, on the contrary, infinitely raises my worth as an intelligence by my personality, in which the moral law reveals to me a life independent of animality and even of the whole sensible world, at least so far as this may be inferred from the purposive determinationw of my existence by this law, a determination not restricted to the conditions and boundaries of this life but reaching into the infinite.

DEFINITION

Practical principles are propositions that contain a general determination of the will, having under it several practical rules. They are subjective, or maxims, when the condition is regarded by the subject as holding only for his will; but they are objective, or practical laws, when the condition is cognized as objective, that is, as holding for the will of every rational being.

Remark

If it is assumed that pure reason can contain within itself a practical ground, that is, one sufficient to determine the will, then there are practical laws; otherwise all practical principles will be mere maxims. Within a pathologically affected will of a rational being there can be found a conflict of maxims with the practical laws cognized by himself. For example, someone can make it his maxim to let no insult pass unavenged and yet at the same time see that this is no practical law but only his maxim – that, on the contrary, as being in one and the same maxim a rule for the will of every rational being it could not harmonize with itself. In cognition of nature the principles of what happens (e.g., the principle of equality of action and reaction in the communication of motion) are at the same time laws of nature; for there the use of reason is theoretical and determined by the constitution of the object. In practical 5:20cognition – that is, cognition having to do only with determining grounds of the will – the principles that one makes for oneself are not yet laws to which one is unavoidably subject, because reason, in the practical, has to do with the subject, namely with his faculty of desire, to whose special constitution the rule can variously conform. A practical rule is always a product of reason because it prescribes action as a means to an effect, which is its purpose. But for a being in whom reason quite alone is not the determining ground of the will, this rule is an imperative, that is, a rule indicated by an “ought,” which expresses objective necessitation to the action and signifies that if reason completely determined the will the action would without fail take place in accordance with this rule.

Why this Critique is not entitled a Critique of Pure Practical Reason but simply a Critique of Practical Reason generally, although its parallelism with the speculative seems to require the first, is sufficiently explained in this treatise. It has merely to show that there is pure practical reason, and for this purpose it criticizes reason’s entire practical faculty. If it succeeds in this it has no need to criticize the pure faculty itself in order to see whether reason is merely making a claim in which it presumptuously oversteps itself (as does happen with speculative reason). For, if as pure reason it is really practical, it proves its reality and that of its concepts by what it does and all subtle reasoning against the possibility of its being practical is futile.

With this faculty transcendental freedom is also established, taken indeed in that absolute sense in which speculative reason needed it, in its use of the concept of causality, in order to rescue itself from the antinomy into which it unavoidably falls when it wants to think the unconditioned in the series of causal connection; this concept, however, it could put forward only problematically, as not impossible to think, without assuring it objective reality, and only lest the supposed impossibility of what it must at least allow to be thinkable call its being into question and plunge it into an abyss of skepticism.

The theoretical use of reason was concerned with objects of the cognitive faculty only, and a critique of it with regard to this use really dealt only with the pure cognitive faculty, since this raised the suspicion, which was afterwards confirmed, that it might easily lose itself beyond its boundaries, among unattainable objects or even among contradictory concepts. It is quite different with the practical use of reason. In this, reason is concerned with the determining grounds of the will, which is a faculty either of producing objects corresponding to representations or of determining itself to effect such objects (whether the physical power is sufficient or not), that is, of determining its causality. For, in that, reason can at least suffice to determine the will and always has objective reality insofar as volition alone is at issue. The first question here, then, is whether pure reason of itself alone suffices to determine the will or whether it can be a determining ground of the will only as empirically conditioned. Now there enters here a concept of causality justified by the Critique of Pure Reason although not capable of being presented empirically, namely that of freedom; and if we can now discover grounds for proving that this property does in fact belong to the human will (and so to the will of all rational beings as well), then it will not only be shown that pure reason can be practical but that it alone, and not reason empirically limited, is unconditionally practical. Consequendy, we shall not have to do a critique of pure practical reason but only of practical reason as such. For, pure reason, 5:16once it is shown to exist, needs no critique. It is pure reason that itself contains the standard for the critical examination of every use of it. It is therefore incumbent upon the Critique of Practical Reason as such to prevent empirically conditioned reason from presuming that it, alone and exclusively, furnishes the determining ground of the will. If it is proved that there is pure reason, its use is alone immanent; the empirically conditioned use, which lays claim to absolute rule is on the contrary transcendent and expresses itself in demands and commands that go quite beyond its sphere – precisely the opposite relation from what could be said of pure reason in its speculative use.

The Critique of Practical Reason, published in 1788, is the second of Kant’s three Critiques, falling between the Critique of Pure Reason (first edition: 1781, second edition: 1787) and the Critique of Judgment (1790). It is also the second of his three major works devoted to moral theory, along with the Groundwork of the Metaphysics of Morals (1785) and the Metaphysics of Morals (1797). These works develop an account of morality that reacts to those found in both the empiricist and the rationalist traditions, and together they constitute Kant’s lasting contribution to moral theory.

Certain remarks in the Groundwork suggest that Kant did not originally plan a separate critique of practical reason. He notes that although a critique of practical reason is the only foundation for a metaphysics of morals (i.e. a systematic classification of human duties on a priori grounds), the need for critique is less pressing in the case of practical reason than it is for speculative reason, and that an outline of such a critique would suffice for his purposes. In moral thought, ordinary reason is more easily brought “to a high degree of correctness and precision” in that authoritative practical principles are revealed through the workings of ordinary moral consciousness, while in its “pure but theoretical use, reason is wholly dialectical,” tending to make illusory and illegitimate metaphysical claims. Furthermore, executing a critique of practical reason would introduce complexities not absolutely necessary to a presentation of the basic principle of duty [G 4: 391]. The idea of writing a separate critique of practical reason appears to have occurred to Kant while he was revising the Critique of Pure Reason for its second edition.

Pure reason always has its dialectic, whether it is considered in its speculative or in its practical use; for it requires the absolute totality of conditions for a given conditioned, and this can be found only in things in themselves. Since, however, all concepts of things must be referred to intuitions which, for us human beings cannot be other than sensible and hence do not let objects be cognized as things in themselves but only as appearances, in whose series of the conditioned and conditions the unconditioned can never be found, an unavoidable illusion arises from the application of this rational idea of the totality of conditions (and so of the unconditioned) to appearances as if they were things in themselves (for, in the absence of a warning critique they are always held to be such), an illusion which, however, would never be noticed as deceptive if it were not revealed by a conflict of reason with itself in the application to appearance of its basic principle of presupposing the unconditioned for everything conditioned. By this, however, reason is forced to investigate this illusion – whence it arises and how it can be removed – and this can be done only through a complete critical examination of the whole pure faculty of reason; thus the antinomy of pure reason, which becomes evident in its dialectic, is in fact the most beneficial error into which human reason could ever have fallen, inasmuch as it finally drives us to search for the key to escape from this labyrinth; and when this key is found, it further discovers what we did not seek and yet need, namely a view into a higher, immutable order of things in which we already are and in which we can henceforth be directed, by determinate precepts, to carry on our existence in accordance with the highest vocation of reason.