In Kant und die Berliner Aufklärung: Akten des 9. Internationalen Kant-Kongress
(Berlin: de Gruyter, 2002), 29-38.
Kant’s Doctrine of the Primacy of Pure Practical
Reason
and the Problem of a Unitary System of Philosophy
Rex Gilliland,
The theme in the background of this essay is the role of the practical/theoretical distinction in Kant’s thought. It is a distinction Kant relies on heavily in defining the faculties and their objects, and consequently in determining the main divisions of philosophy. Not surprisingly, it is also a division he attempts to bridge in order to maintain the unity of his thought. In the Architectonic of the First Critique, Kant writes: “The legislation of human reason (philosophy) has two objects, nature and freedom, and therefore contains not only the law of nature, but also the moral law, presenting them at first in two distinct systems, but ultimately in one single philosophical system” (A 840/B 868; see A 645/B 673, A 474-475/B 502-503). He poses a similar task in the Groundwork, while discussing the relation of the First and Second Critiques: “If the critique of pure practical reason is to be complete, then it must be possible to present the unity of pure practical reason and speculative reason in a common principle; for, ultimately, there can be only one and the same reason, differentiated solely in its application” (GMS 4:391; see KpV 5:90-91).[1]
When considering how Kant attempts to demonstrate the unity of practical and theoretical philosophy or the unity of practical and speculative reason, which amounts to the same thing for him, many commentators turn to the Third Critique.[2] However, I maintain that Kant’s discussion of the primacy of pure practical reason in the Second Critique is more relevant. In the Architectonic, Kant states that the systematic unity of philosophy arises from the relation of essential ends in the faculty of reason. The ultimate end, to which all the other essential ends of reason are subordinate, is moral philosophy (A 832-834/B 860-862, A 839-840/B 867-868; see A 328/B 385, A 804/B 832). “On the Primacy of Pure Practical Reason in Connection with Speculative Reason” is the only place where Kant examines the subordination relationship between the various ends of reason in detail. Though he does discuss the ways in which the concepts of pure practical reason supplement or support speculative reason in this section as well as in other works, a relationship of this type merely suggests that these faculties are unified in the noumenal realm since the unity indicated here, the unity of the practical concept of freedom and the theoretical concept of nature, is inaccessible to finite reason. In contrast, Kant’s examination of the relationship of the ends of reason provides a substantive account of the unity of practical and theoretical reason because it explicitly describes the relationship of these faculties.[3] In this essay, I will closely examine “On the Primacy of Pure Practical Reason,” distinguishing two senses in which pure practical reason has primacy over speculative reason, and will conclude by returning to the issue of how this section helps to clarify the systematic unity of Kant’s thought.
In “On the Primacy of Pure Practical Reason,” Kant discusses the relationship of practical and speculative reason, the two basic uses of the faculty of reason. Though Kant mentions certain general characteristics that both share as uses of reason – working with principles, possessing an interest in the extension of their exercise, and striving to maintain consistency – he is concerned primarily with the relationship of their principles. Kant considers two possible ways in which the principles of practical and speculative reason might be related, namely, subordination and coordination. In the first, one principle is “the prime ground of determination” for others, and in the second, as it appears from Kant’s description, neither of the two principles determines the other (KpV 5:119). Coordination, then, is a relationship of mutual independence while subordination is a relationship of one-sided dependence. Primacy, for Kant, is a type of subordination relationship, one in which the superordinate principle is not itself subordinate to any other principle: It stands first in a chain of otherwise subordinate principles. Kant considers three possible relationships between the principles of practical and theoretical reason in this section: (1) The principles of practical reason have primacy over the principles of speculative reason; (2) The principles of speculative reason have primacy over the principles of practical reason; and (3) The principles of practical and speculative reason are coordinate, i.e., they are independent from one other.
What is meant here by the determination or dependence of a subordinate principle? The answer to this question is quite complicated because it depends on the types of practical and theoretical principles whose relationship is being examined. Kant considers the relationship of two different types of practical and theoretical principles, and the form of dependence found in each case is different. In the first case, the principles whose relationship is at issue are the interests of each faculty, principles that guide the exercise of particular faculties. And in the second, at issue is the relationship of the principles that pertain to the objects of practical and theoretical reason – nature and freedom – the regions with which each faculty is concerned. In this regard, Kant is primarily concerned with the relationship between the practical postulates and the regulative ideas (see KpV 5:134, 143). In order to distinguish the second type of principles from interests, I will refer to them as ‘principles of knowledge’ since each faculty of reason formulates the knowledge of its object in principles of this sort. The subordination of one interest to another, as we will see, is much like the subordination of a means to an end: A means is dependent on an end because its purpose is determined in relation to the purpose of the end. How it serves the end depends upon the nature of the end. On the other hand, a subordinated principle of knowledge is dependent on the superordinate principle of knowledge for epistemic support or justification. Its epistemic status is determined at least in part by the other principle.
At the beginning of “On the Primacy of Pure Practical Reason,” Kant defines to two senses of primacy, a general and a narrower practical sense (KpV 5:119), though it is possible to identify another sense at play in Kant’s discussion. The general sense of primacy is apparently the primacy found in the relations of any types of principles, though, as we will see below, Kant only uses it in this section when referring to the relationship of principles of knowledge. The narrower practical sense of primacy pertains to the relationship of the interests of the faculties of the soul. I will refer to it as ‘teleological primacy’.[4] ‘Interest’ and ‘end’ are quite similar concepts, though there are significant differences between them. The notion of interest, for Kant, is broader than the notion of end: It captures more fully the phenomenon of rational volition, encompassing not only the end, the conceptual representation that directs reason toward a potential goal, but also the ‘phenomenal feel’ of volition, the drive or attraction of the will toward a particular end. As it is being used in this passage, however, ‘interest’ is also narrower than ‘end’ since it relates to a very specific type of end, namely, the highest end of a particular faculty of the soul. An interest is a principle “that can be ascribed to every faculty of the soul,” and “contains the condition under which alone the exercise of this faculty can advance.” This condition is the highest end of a particular faculty, set by its interest, and the exercise of a faculty only advances when it progresses towards this end. Some ends of a faculty are not part of its interest: According to Kant, maintaining consistency is a necessary condition for any use of reason, but is not part of the interest of reason because it does not extend reason’s scope.
Kant states that the interest of speculative reason “consists in the knowledge of objects up to the highest a priori principles,” and the interest of practical reason “lies in the determination of the will with respect to the final and complete end” (KpV 5:120). The first definition is problematic, however, because throughout the remainder of the section Kant uses a much different definition, namely, that the interest of speculative reason lies in the restriction of speculative folly.[5] As we will see, the tension between these two definitions lies at the heart of the problem Kant is contending with in this section.
In addition to teleological primacy, we can identify another type of primacy at play in Kant’s discussion, a type of primacy found between principles of knowledge. I will refer to this as ‘epistemic primacy’.[6] In fact, when Kant refers to a type of primacy that is not teleological primacy, places where we would be expecting primacy in general (since this is the only other type of primacy that he mentions), the issue is always epistemic primacy – a relationship of principles of knowledge – rather than a general sort of primacy that would include both teleological and epistemic primacy. However, one might suspect that Kant conflates teleological and epistemic primacy since he appears to use them virtually interchangeably. In the second and third paragraphs of this passage, where teleological primacy is the explicit issue, Kant’s discussion hinges on epistemic primacy, and in the fourth paragraph, where Kant is arguing for the epistemic primacy of pure practical reason, he argues in part from the teleological primacy of pure practical reason. If Kant is not conflating these two types of primacy, there must be a relationship between them that justifies him in using them so closely. This relationship is captured in the following claim, stated in a rough form that will need to be qualified: Teleological primacy entails epistemic primacy. The existence of a relationship of principles in which a particular faculty has epistemic primacy is caused or brought about by the fact that this faculty also has teleological primacy. This claim is supported by three points. First, it follows from Kant’s description of the faculties. As the section under consideration shows, Kant understands the faculties in the same way that he conceives the action of a rational agent: The activity of both is guided by a highest end. The activity of a faculty of reason includes the determination, testing, and acceptance or rejection of principles of knowledge. Since the action of a faculty is guided by an end, if a faculty is subordinated to the end of another faculty, it follows that the subordinate faculty will accept the superordinate faculty’s principles of knowledge as a foundation for its own principles of knowledge when the former are necessary for the superordinate faculty’s end. Second, Kant suggests this entailment relationship in the third paragraph of this section, as we will see. And third, unless teleological primacy entails epistemic primacy, Kant’s argument in the fourth paragraph will not work, since it rests on this assumption. This will be discussed below.
In the second paragraph, Kant raises the issue of teleological primacy, and given the discussion that follows, he clearly thinks that this issue is closely related to the issue of epistemic primacy. According to Kant, if the interest of practical reason were primary, speculative reason would accept and integrate the principles of practical reason as grounds for its own principles. And if the interest of speculative reason were primary, speculative reason would reject the principles of practical reason since it cannot establish them itself. Consequently, practical reason would not be able to “assume and think as given anything further than what speculative reason affords from its own insight” (KpV 5:120). In this paragraph, Kant is claiming that the teleological primacy of practical reason entails the epistemic primacy of practical reason, and that the teleological primacy of speculative reason entails the epistemic primacy of speculative reason: If the interest of a particular faculty of reason predominates, its principles of knowledge do also.
This claim about entailment is illustrated in Kant’s discussion of the relationship of speculative and pathological practical reason. According to Kant, if speculative reason was teleologically primary, it would reject the principles of knowledge of pathological practical reason. This is because these principles would introduce speculative folly into theoretical knowledge, due to their arbitrary and potentially contradictory nature (KpV 5:120-121). The interest of pathological practical reason (a species of practical reason) lies in setting happiness as the highest end of the will. Though happiness – the greatest possible satisfaction of the inclinations – is formally identical in every case, its meaning differs significantly among individual persons since the inclinations of each individual are different (GMS 4:399). Kant considers the principle of happiness to be arbitrary because it depends on the interest of the inclinations, which vary from individual to individual, in contrast to principles based on reason, which are universal. As a result, pathological practical reason does not set a consistent law for the will. Due to its arbitrary nature, the meaning of happiness for two different people is potentially, and in fact very likely to be, contradictory. The arbitrariness and potential contradictoriness of this principle is especially problematic for Kant when an individual makes a claim about the noumenal realm by determining the state of the afterlife according to her view of happiness. If we take the afterlife as that state which will bring the greatest happiness, this would lead to wildly different claims about the noumenal realm, which is a perfect example of what Kant calls speculative folly.[7]
In the second and third paragraphs of this section, Kant argues that there are no grounds for speculative reason to reject the principles of knowledge of pure practical reason – the practical postulates of God, freedom, and immortality – since these principles do not conflict with its interest. However, he goes even further, arguing in the third paragraph that speculative reason should accept these principles because they are the product of another faculty of reason. This argument rests on a claim Kant makes about the unity of reason, a claim that perhaps most clearly connects Kant’s doctrine of the primacy of pure practical reason to the issue of the unity of reason and the unity of the system of philosophy raised in the introduction of this essay. According to Kant, the claim that “it is only one and the same reason that judges a priori by principles, whether for a theoretical or for a practical purpose [Absicht]” (KpV 5:121) is only possible on the basis of his argument for the existence of pure practical reason developed earlier in the Second Critique. By proving the existence of pure practical reason, Kant has accomplished a necessary step toward demonstrating the unity of reason: If pure practical reason did not exist, reason could not be united due to the inherent conflict between speculative and pathological practical reason. As we have seen, for Kant maintaining consistency is a necessary condition for any use of reason, and an inherent conflict within reason would undermine the very nature of reason. Since he has demonstrated the existence of pure practical reason, Kant has preserved the possibility of the unity of reason, and of rationality itself. It is in his discussion of the primacy of pure practical reason that Kant finally satisfies the “unavoidable requirement” of explaining the unity of reason in terms of a single principle, a task he highlights earlier in the Second Critique (KpV 5:90-91), as well as in the First Critique and the Groundwork, as we saw above.[8]
Given the fact that the unity of reason is not only something that Kant needs to prove in order to demonstrate the unity of his thought, but is also a possibility that must be preserved in order that rationality itself be possible (even as an ideal), Kant’s claim that speculative reason must accept the practical postulates since they are the product of another faculty of reason appears to be well justified. If speculative reason did not accept the practical postulates, it would jeopardize the unity of reason as well as rationality in general, because speculative and pure practical reason would inherently conflict with one another. The latter would maintain claims about the noumenal realm (i.e., claims about the existence of freedom, God, and immortality) that the former would reject.
For Kant, however, it appears that in relation to the need to maintain the unity of reason, teleological primacy has a certain priority over epistemic primacy. Speculative reason accepts the practical postulates “just as soon as they are sufficiently certified as belonging imprescriptibly to the practical interest of pure reason” (KpV 5:121). What this implies is that the need to maintain the unity of reason entails the teleological primacy of pure practical reason, and that the epistemic primacy of pure practical reason follows from there. The interest of speculative reason in avoiding speculative folly is subordinated to the interest of pure practical reason. This is seen in the fact that speculative reason must accept and integrate the practical postulates because these principles are required by the interest of pure practical reason, i.e., the determination of the moral law as the highest end of the will. Since the interests of these two faculties do not conflict, speculative reason does not abandon its interest in the restriction of speculative folly by accepting the practical postulates; now, however, its interest serves the interest of pure practical reason by warding off superstition and fanaticism (see KpV 5:135-136).[9] Perhaps even more interesting, the notion of teleological primacy shows that Kant’s two definitions of the interest of speculative reason may not be incompatible after all. For by accepting the practical postulates, speculative reason does not abandon its interest in avoiding speculative folly, while at the same time establishing a stronger connection with the highest a priori principles.
Kant’s claim that the unity of practical and theoretical reason can only be preserved by demonstrating the existence of pure practical reason is a useful way to counter those who criticize him for ever moving beyond the Transcendental Dialectic. However, these critics have a ready response: Kant’s attempt to ground theoretical principles in the practical postulates appears to conflict with the limits he sets for speculative knowledge in the Transcendental Dialectic. But Kant is quite careful to qualify his claims about the grounding the practical postulates provide for the regulative ideas, in order to avoid contradicting the First Critique by changing the latter into constitutive principles and extending speculative knowledge beyond its proper limits. In the third paragraph, Kant states that speculative reason must remember “that [the practical postulates] are not its own insights” (KpV 5:121). Seen in the light of the final sections of the Dialectic of Pure Practical Reason, where Kant discusses this issue in more detail, he is claiming that the practical postulates provide some support for the principles of speculative reason without extending the knowledge of this faculty. That may seem like a difficult position to defend. In any case, Kant attempts to do so by arguing that the practical postulates justify speculative reason’s assumption of the regulative ideas by providing confirmation: Whereas speculative reason was only able to show that the objects of these principles were not impossible, the practical postulates demonstrate their objective reality. On the other hand, according to Kant, the practical postulates do not extend speculative knowledge because they do not provide any intuitions or determinations of the noumenal objects of freedom, God, and immortality: Although the practical postulates demonstrate the existence of the objects of the regulative ideas, they do not make it possible for these principles to connect with their objects, or for speculative reason to make any positive use of these objects. By accepting the practical postulates, according to Kant, theoretical knowledge of reason in general is expanded but not theoretical knowledge of these noumenal objects. This suggests that the first form of speculative interest is satisfied, though in a somewhat limited way (see KpV 5:132-135).[10]
In the final paragraph, as indicated above, Kant argues for the epistemic primacy of pure practical reason. This may appear a bit strange because he just finished arguing for this in the previous paragraph. Here, however, he uses a different argument, which also serves as the summary of the entire section. In the final paragraph, Kant attempts to demonstrate the necessity of the epistemic primacy of pure practical reason by using the process of elimination to show the impossibility of all the other imaginable relations between the principles of knowledge of speculative and pure practical reason. We are already familiar with the various steps of his argument. First, the coordination of practical and speculative reason is ruled out because it would lead to conflicts between these two faculties of reason, the latter denying the principles of the former. And, second, the epistemic primacy of speculative reason over practical reason is ruled out “because every interest is ultimately practical” (KpV 5:121). How does the teleological primacy of pure practical reason rule out the epistemic primacy of speculative reason? Speculative reason would only be able to reject the principles of knowledge of pathological or pure practical reason if its interest were primary, because otherwise its interest will be subordinated to the needs of the interest of another faculty.[11] The teleological primacy of practical reason implies the epistemic primacy of practical reason because the faculty will require practical principles in order to realize its highest end, and these principles will only be accepted and integrated by speculative reason as the ground of its own principles, given the fact that practical principles of this type contain claims about the noumenal realm. These points support the claim I made above that Kant’s argument here depends on the claim that the teleological primacy of a faculty implies its epistemic primacy.
As we have seen, Kant argues in “On the Primacy of Pure Practical Reason” that pure practical reason is both teleologically and epistemically primary in its relation to speculative reason: Both the interest and the principles of knowledge of speculative reason are subordinate to those of pure practical reason. By doing this, Kant has been able to show how these faculties work together toward the same ends and to show that their knowledge is consistent. As I indicated in the introduction, the notion of teleological primacy is especially significant, not only because it determines epistemic primacy, but also because it helps us to understand how Kant conceives both the unity of reason and the systematic unity of philosophy. Reason is united, for Kant, when the exercise of all of its faculties are guided by the same end, rather than working independently from one another toward potentially divergent and conflicting ends. This is only possible, according to Kant, when the interests of the other faculties of reason are subordinated to the interest of pure practical reason – i.e., when the moral law is set as the highest end of the will. What this demonstrates is that the ultimate purpose of speculative reason and theoretical philosophy, for Kant, is to assist the individual in following the moral law. It may seem strange to suggest that they would be capable of this, though, as we have seen, Kant claims that speculative reason serves this purpose in at least one way, namely, by warding off superstition and fanaticism in moral thought. This purpose is not as rigid a demand as it sounds and can be satisfied quite indirectly. For example, other ways in which speculative reason can serve this purpose are by fulfilling the duty to develop one’s talents, and more specifically by developing one’s general reasoning ability, which would help to improve one’s moral reasoning.
However, some may not find the type of unity Kant argues for to be very satisfying.[12] Even if it is true that speculative reason and theoretical philosophy serve the interest of pure practical reason, does this tell us very much about the way in which the faculties of reason on the one hand and practical and theoretical philosophy on the other are united in their very natures? Is not human reason still caught in the straits of a de facto dualism? One may set the standard for unity much higher than Kant has fulfilled here – namely, identity. In order to show that the faculties of reason or the divisions of philosophy are ultimately identical, it would be necessary for Kant to demonstrate that their respective objects, freedom and nature, are identical. This, however, is an unwarranted expectation for Kant to accomplish within the constraints of the critical project because it would require knowledge of the noumenal, which would push human reason beyond its proper limits. By explaining the unity of reason and the unity of the system of philosophy in terms of a hierarchy of the ends of reason and by providing us with an idea of how nature and freedom might be identical in the noumenal realm, in the Third Critique and elsewhere, Kant has gone as far as he can while still remaining within the limits he sets for human reason in the critical project.
[1]Kant makes a similar claim
in the Second Critique, and he connects the issue of the systematic
unity of philosophy and the unity of the faculty of reason (KpV
5:90-91/95).
[2]See, for example, David A. White, “On Bridging the Gulf between Nature and Morality in the Critique of Judgment,” Journal of Aesthetics and Art Criticism 38 (1979-80), 179-188, and Th. J. Donaldson, “Connecting Nature and Freedom in Kant’s Third Critique,” Auslegung, 1-2 (1973-1975), 98-107.
[3]See 5:175, 176, 196, A
805-819/B 833-847. The limitations of the arguments in the Third Critique
can be seen again in relation to the issue of the systematic unity of
philosophy. The doctrine of primacy pertains directly to both divisions of
philosophy since it determines the end of each. On the other hand, the concepts
of the faculty of judgment, such as the purposiveness
(Zwecklichkeit) of nature, are restricted to
the system of theoretical philosophy (5:179, 197; 20:202). It follows that
these concepts cannot demonstrate the unity of both divisions of philosophy
except quite indirectly, i.e., by analogy to the concepts of practical
philosophy. I am not claiming that the type of argument found in the Third
Critique is irrelevant. Indeed, Kant argues for the unity of reason and of
the system of philosophy in both ways, each with their own advantages. His
argument for the unity of ends provides an explicit description of this unity,
while his argument by analogy aims for a deeper type of unity, i.e., an
identity of nature and freedom that is inaccessible to finite reason, unlike
the unity of ends in which practical and theoretical concepts remain distinct.
[4]I use ‘teleological primacy’ to indicate the primacy of the ends and volitions of the will, not the ends of natural purposiveness discussed in the Third Critique.
[5]For discussions of the problem of the potential incompatibility of Kant’s two definitions of the interest of speculative reason see Lewis White Beck, A Commentary on Kant’s Critique of Practical Reason (Chicago, University of Chicago Press, 1960), 249, fn. 29, and Robert Louden, Morality and Moral Theory (Oxford: Oxford University Press, 1992), 185-186, n. 24.
[6]According
to Stephen Körner, what I am calling epistemic
primacy pertains to the content of the faculties of practical and theoretical
reason, in contrast to their interests (“Über das wechselseitige Verhältnis der theoretischen und der praktischen Vernunft,” Akten des 4. Internationalen
Kant-Kongresses, Part 3 [
[7]Some commentators have argued that in cases of conflict, pure practical reason overrides speculative reason, and that this is the central meaning of Kant’s notion of primacy. See Roger Sullivan, Immanuel Kant’s Moral Theory (Cambridge: Cambridge University Press, 1989), 104, and G.J. Warnock, “The Primacy of Practical Reason,” Proceedings of the British Academy 52 [1966], 262. However, as we will see, conflict plays a merely hypothetical role in this section: As Kant indicates, there is in fact no conflict between the interests of speculative and pure practical reason (KpV 5:121).
[8]In “Kant on the Unity of
Theoretical and Practical Reason” (Review of Metaphysics 52 [1998]),
Pauline Kleingeld argues that Kant’s claim that
practical and theoretical reason are merely separate uses of the one and the
same reason should be interpreted as a regulative principle since this is the
only way that Kant can consistently hold a number of apparently incompatible
claims about the unity of reason (see 311-313). While I agree with Kleingeld that the unity of reason suggested by the purposiveness of nature is quite different than the unity
of reason as a faculty with distinct practical and theoretical uses (313,
322-336), I disagree with her claim that Kant indefinitely postpones the task
of demonstrating the latter type of unity. As we have seen above, Kant
repeatedly asserts that the critical project will not be complete until this
task is accomplished, and the passages where he postpones this task all precede
the section “On the Primacy of Pure Practical Reason,” where, in my view, he
finally demonstrates the unity of the faculty of reason.
[9]Kant’s doctrine of the primacy of pure practical reason amounts to the prescription that the interests of the other faculties of the soul be subordinated to the interest of pure practical reason. See Körner, ibid.; Gilles Deleuze, Kant’s Critical Philosophy: The Doctrine of the Faculties, trans. Hugh Tomlinson and Barbara Habberjam (Minneapolis, University of Minnesota Press, 1984), 44; and YirmiahuYovel, Kant and the Philosophy of History (Princeton, N.J.: Princeton University Press, 1980), 289.
[10]If Kant’s claims are correct, the type of determination or support that the epistemic primacy of pure practical reason provides for the principles of knowledge of speculative reason is limited. Speculative reason by itself provides an adequate degree of justification for its assumption of the regulative ideas, though the existence of their objects is far from certain. The practical postulates add increased support to this assumption by demonstrating the existence of freedom, God, and immortality, though the dependence of the regulative ideas on this support is indeed quite limited. The fact that this justification suggests a connection between the knowledge of speculative and pure practical reason (without explaining the nature of this connection very explicitly) is an aspect of the epistemic primacy of pure practical reason that is perhaps at least as significant as the limited epistemic support that the practical postulates provide. It is in this way that “On the Primacy of Pure Practical Reason” suggests, like the Third Critique, that the objects of theoretical and practical philosophy are identical in the noumenal realm.
[11]If pure practical reason is teleologically primary, it is not necessary for speculative reason to reject the noumenal claims of pathological practical reason: The claims of pathological practical reason are already rejected because they conflict with the interest of pure practical reason, i.e., setting the moral law as the highest end of the will.
[12]See Gerold Prauss, “Kants Problem der Einheit theoretischer und praktischer Vernunft,” Kant-Studien 22 (1981), 292.