Comentari de text sobre una part de la Critica de la Raó Pràctica de Kant

27 d'octubre de 2009 0

Kant’s Ethics

Prof: Agnes Heller


On the deduction of the principles of pure practical reason


On the warrant of pure reason in its practical use to an extension which is not possible to it in its speculative use


“But if we examine the same actions in reference to reason (…), if we compare these actions with reason in a practical regard, then we find a rule and order quite different from the order of nature”.

Immanuel Kant

Critique of Pure Reason (A550, B578)[1]



– Change of perspective –


If The Critique of Pure Reason aimed at the question What can I know?, the Critique of Practical Reason addresses this other question: What must I do? These two issues are -in Kant’s opinion- essentially different, as well as they place reason in two opposite, though related, dimensions; namely theory and praxis.


It is important to make clear what difference Kant sees between these two dimensions. I judge this as a worthwhile endeavor because the part of the 2nd Critique which I am about to analyze[2] – “On the deduction of the principles of pure practical reason” – is precisely the point in the text where Kant states both the differences and the connections between the 1st and the 2nd Critiques and, consequently, between the practical and the theoretical uses of pure reason as it draws on the issue of the pure concepts of reason. His goal is to secure freedom positively as a principle of practical reason by establishing a causality that cannot be accounted for as pertaining to the natural law of the senses. The main problem I see for the consecution of this goal is whether this approach to freedom from a practical perspective will leave the strict boundaries drawn in the 1st Critique untouched and, hence, if it will be possible to avoid the risk of transcendental illusions. This paper intends to analyze Kant’s argumentation to secure freedom by separating the theoretical and practical uses of reason in order to see if these boundaries hold. 


What does, then, human behavior have to do with Kant’s critical project? Why has he developed his moral doctrine as a critique of practical reason? Fundamentally, Kant understands “critique” as the examination of the possibilities and pretensions of a faculty necessary to reveal those limits within which the use of such faculty is legitimate. Is it possible for a faculty to go beyond its own powers and, thus, to open paths that may nevertheless lead it nowhere. The first Critique examined the faculty of cognition that every reason has. Kant’s conclusions are known: reason can only act legitimately within the limits of the “possible experience”. When it tries to overcome this limit, it then gets lost and produces unfounded knowledge. That is, what reason produces under these circumstances is not scientific knowledge. However, the theoretical function is not the only function of reason. Theoretical reason and practical reason are, in fact, two functions of the same faculty, which proceeds always through principles a priori. Therefore, in both cases, it is a pure reason. Now, while the object of the theoretical function is knowledge, the object of practical reason is that which is desired or decided. In other words, practical reason does not actually want to cognize anything, it wants just to lead the will and guide our actions. This is, indeed, a very old philosophical quest: the distinction between knowing and knowing what to do.


Hence, Kant undertakes a radical change of perspective. In the first Critique the pure-theoretical function of reason was under judgment, while in the second it is its empirical-practical function that needs to be examined. In the former, its pure-theoretical use was declared illegitimate, because it was transcendent, meaning beyond its empirical boundaries; whereas in this 2nd Critique is its empirical use which is transcendent, meaning beyond its pure a priori region, and therefore, illegitimate. If there exists such a thing named pure practical reason, it does not require a critique. As long as it is a pure reason, it contains already the complete rules for its use.


This change in perspective brings about another inversion: theoretical reason begins with sensibility, whereas practical reason makes its start with the moral law a priori. The first “fact” that the theoretical reason needs to give reality to its content is an intuition that comes from the senses. Then, reason builds the phenomenon with its pure intuitions of time and space, and so on, through categories, to be able to form concepts. However, in the practical use of pure reason, “the first fact” is the moral law, and its possibility as a universal, rational formula. Moreover “the moral law is given, as it were, as a fact of pure reason of which we are a priori conscious and which is apodictically certain, though it be grated that no example of exact observance of it can be found in experience. Hence the objective reality of the moral law cannot be proved by any deduction, by any efforts, of theoretical reason, speculative or empirically supported”. (5:47)




Ratio cognoscendi of freedom-


This assertion opens for pure practical reason the possibility of introducing itself in the noumenal world without going beyond its own sphere of reality. However, it still does not show clearly whether it can find a way out of that noumenal world. What the transcendental ideas lack when they are to be conceived is the possibility of being under the form of an intuition. There can be no experience of a transcendental idea. However, what was forbidden for pure theoretical reason might be now allowed for pure practical reason. The concept of praxis might be the door through which the mere logical possibility of a transcendental idea becomes an objective reality, that is, its way-out. Transcendental freedom might become real by the immediate nature of action, and therefore it may as well be conceived not hypothetically but assertorically, in its intelligible, noumenal dimension.

For this to be possible, it is necessary that the supersensible nature of rational beings alone affects the sensible reality of their actions. But, how is it possible that a moral law (that is necessarily universal and created by the sole reason) affects the empirical realm of actions? Even more: how can reason be, in fact, the only legislator of the behavior in rational beings if they remain subject to the causality of law of nature?


The ratio cognoscendi of freedom is the moral law, and Kant’s argumentation goes as follows: “This Analytic shows that pure reason can be practical -that is, can of itself, independently of anything empirical, determine the will – and its does so by a fact in which pure reason in us proves itself actually practical, namely autonomy in the principle of morality by which reason determines the will to deeds”. (5:42)


What Kant undertakes in his second Critique, then, after the statement of the four theorems of the moral law is, by his own account, a very difficult and obscure task: can we deduce freedom positively from the practical function of the pure reason? And, does this possibility teach us something about the nature of the transcendental ideas in general and about freedom in particular?


Kant needs, then, to find validity for a freedom by which the law may be determined. He has to find a law-abiding will capable of creating universal maxims and independent enough to affect life beyond natural causes. Moreover, “this (moral) law is to furnish the sensible world, as a sensible nature (in what concerns rational beings), with the form of a world of the understanding, that is, supersensible nature, thought without infringing upon the mechanism of the former (5:43)”.


Kant has shown that a moral law which only has universal maxims is itself a law independent of experience. Consequently, there is something in our reason that is able to produce such determining maxims for the will to comply with. However, this raises a gigantic problem. How can freedom be possible -even in a practical sense – if a being that belongs to a sensible world is always subject to the natural law of causality. How are freedom and mechanism to coexist?



-Another causality-


 Here Kant claims to have uncovered another kind of causality. As he states in the first Critique, “only two kinds of causality can be conceived in regard to what occurs, viz., either a causality according to nature or one from freedom. The causality according to nature is the connection, in the world of sense, of one state with a previous state upon which the state follows according to a rule. Now the causality of appearances rests on conditions of time…By freedom, on the other hand, in the cosmological sense of the term, I mean the power to begin a state on one’s own. (A533. B561)


The first kind of causality, as stated in the first Critique, referred to the relations of the objects in the sensible sphere. Through pure categories of the understanding we are able to understand phenomena as a part of a chain of causes, and also produce synthetic a priori judgments that are universally valid for all objects of both the sensible (potential) and the sensed (actual) world. The human being -says Kant- recognizes himself as a subject of this causality too, for it lives under the law of nature.


And yet, with the discovery of autonomy (with the presence of a internal moral law, with the strength of the categorical imperative and its rational necessity and its independence of any matter, and also with the autonomy of the pure will) human consciousness is aware of itself in another side, as a being in itself- conscious of its existence as determinable in an intelligible order of things -conscious of this not, indeed, by a special intuition of itself but according to certain dynamic laws that can determine its causality in the sensible world.” (542). It is implied, then, that there is another kind of causality. Or, at least, another side of it. The causality that comes from the fact that pure practical reason can produce an effect on the will, can be thought as able to determine the will absolutely, even though we Kant denies that we can ever know it, and can, therefore, be part of the sensible world when it guides the action and ignores the claim of sensible inclinations.


Is in this context that Kant offers a platonic analogy. The supersensible nature can be thought of as if it were “natura archetypa” ruled by the law of reason, whereas sensible nature can be expressed as a “natura ectypa”, a copy of the former. This distinction means that the moral law can be understood as a kind of natural law and, yet, at the same time, it cannot be a subject of such a natural law: “hence the difference between the laws of nature to which the will is subject and of a nature which is subject to a will (as far as the relation of the will to its free actions is concerned) rests on this: that in the former the object must be the causes of the representations that determine the will, whereas in the latter the will is to be the cause of the subjects, so that its causality has its determining ground solely in the pure faculty of reason…”. (5:44)


We face here the first problem in this attempt at a deduction. Kant is here trying to state the validity of the idea of freedom in its practical use. For that he needs to find not only a type of maxims that challenge sensible inclinations and grounded independently of all empirical condition, but also to justify a power -freedom of the will- that must be beyond the type of causality by which a specific kind of relation between phenomena is explained. Therefore, this pure practical lawgiving faculty cannot be grounded in any phenomenical nature.


Here we see the radical difference between the theoretical and the practical quest that are particular to each Critique. While the Critique of Pure Reason deals with how pure reason can cognize, the Critique of Practical Reason needs to show how pure reason can be an immediate determining ground for the will. Hence, how our maxims of the moral law can be possible is not a practical question. The law already exist in reason; it, as it were, a fact. What we nevertheless need to know is where does these maxims come from and if they are they independent from experience or not. That is what it means to say that they are able determine the will.




-Moral law of the noumenon and natural law of the phenomenon-


 The causality of nature can be conceived as necessary by means of the interaction of both the possible experience and the pure mechanism of the understanding. Its necessity is a necessity we must assume in the phenomenal world, and yet at the same time universal, since its concept comes from pure reason through the pure categories of the understanding. The objective necessity of the laws of causality can be stated a priori, but the causality itself, namely the relation between objects and their presence in a certain time, is not created by the rational being. We do not create the laws of nature; we just understand nature through these connections.


If this kind of causality were the ground for morality, morality would be an external necessity, and therefore no freedom could ever exist whatsoever. Or, at least, no human freedom. The legislator of nature -if such a thing existed- would also be the free legislator of human action and human will. So, no morality would ever come to be. The only possible universal law thinkable in that context would be an absolute determinism in any human move, so life would be just a piece in a chain of a prefixed destiny.  This impossibility is already stated in the first Critique: “…every human being’s power of choice has an empirical character. This character is nothing but a certain causality of his reason insofar as this causality shows in its effect in (the realm of) appearances a rule whereby one can gather, in terms of their kind and degrees, the bases and actions of his reason and thereby judge the subjective principles of his power of choice. (…) If we could explore all appearances of his power of choice down to the bottom, there would not be a single human action that we could not with certainty predict and cognize as necessary from its preceding conditions. In regard to this empirical character, therefore, there is no freedom”. (A550, B578). 


In order to solve this contradiction between natural necessity and freedom, Kant does not find another exit apart from using the distinction between phenomenon and noumenon. The law of causality is applied to the things insofar their existence is determined in time. If there were no another way to represent the existence of things, or no things that could be represented differently, it would be necessary to reject freedom as an impossible idea.


Consequently, the consciousness of this other causality, if it is to be shown as both necessary and existent, must come from outside natural law, meaning from another universe besides phenomena, namely noumenal. “For insofar as this subject is noumenon, nothing occurs in it and there is found no change requiring dynamical time determination and hence no connection with appearances as causes” (A541. B569.)


It is worth going a little deeper in this distinction in order to be aware of the consequences implied in it. Kant thinks that, if we did not have such double perspective from where we could observe human being and their actions; in other words, if the human being existed only being in itself, and was unable of determining his actions and his self as phenomena, there would not be room for freedom either. Time and space would be determinations belonging to things in themselves, instead of pure intuitions of the human sensibility, and fatalism would be also unavoidable. Placed by God in a world determined by natural causality as part of a chain of causes – in which the creator itself would appear as the first ring – human beings could not envision more freedom than that of reasoning automaton. The only singularity rational beings would have, compared to all other things in nature, would be their consciousness of such an external law. Heteronomy would be the name of their practical realm.


Thus, if human beings were only understood as noumena, and their will could not affect the phenomenical sensible world, there would not be any freedom either. For us to be affected only by the causality of nature, there needs to be a different conception than just that of noumena unable to affect freely its phenomenical self. What is necessary for this causa-noumenon to exist is a conception of human beings according to which their noumenal selves can be responsible for their phenomenical selves. Both sides of the self are necessary to understand how transcendental freedom works as an indetermined causation of the will.




-A practical positive securement of freedom does not extend our knowledge of it-


 If -according to the first Critique– time is the pure intuition for the cognition of the inside (the pace of the sensibility) and hence also the grounds to our understanding of the phenomenon, a noumenal being that not only exists beyond experience, but also over experience, must be a being without time, and therefore, uncognizable.


The consciousness of the existence of freedom “transfers us into an intelligible order of things”. (5:42) But does this transference give us any knowledge beyond experience? Certainly, not a theoretical knowledge, “how this consciousness of moral laws or, what is the same thing, this consciousness of freedom is possible cannot be further explained, its admissibility can, however, be defended in the theoretical Critique”. (5:46) In fact, this is not the goal of practical reason in general, and this deduction in particular. Kant radically separates both uses of reason, in order not to overstep the limits of the pure reason that he has uncovered in the 1st Critique. 


“How a causa noumenon is possible; this it (reason) cannot do, but as practical it does not even concern itself with this inasmuch as it only puts the determining ground of the causality of the human being as a sensible being (which is given) in pure reason (which is therefore called practical), and accordingly uses the concept of cause itself -from whose application to objects for theoretical cognition it can here abstract altogether (since this concept is always found a priori in the understanding, even independently of any intuition) not in order to cognize objects but to determine causality with respect to objects in general, and so for none other than practical purpose; and thus it can transfer the determining ground of the will into the intelligible order of things inasmuch as it readily admits at the same time that it does not understand how the concept of cause might be determined for cognition of these things” (5:46)


Consequently, we have reached the limit of the practical use of the pure reason, in his attempt to deduce freedom. The consciousness of freedom that comes from the consciousness of the being itself does not lead us to discover any new content for the transcendental ideas. The theoretical deduction of the first Critique was able to secure positively the concepts of the understanding within the frame of the possible experience, but “with the deduction (of the supreme principle of practical reason, namely freedom[3]), that is, the justification of its objective and universal validity and the discernment of the possibility of such a synthetic proposition a priori, one cannot hope to get on so well as was the case with the principles of the pure theoretical understanding”. (5:46)


However, the fact of the moral law, its presence in the pure reason, as well as its complete independence of empirical conditions, show us that there is freedom. The idea of this other causality, of this other order, itself different from the natural order, leads us to deduce the actuality of freedom.


Kant has unveiled through this deduction the immanent reality of this transcendental idea. Through practical reason, freedom is stated positively insofar as it is proved that it can determine the will: “The moral law…is able for the first time to give objective though only practical reality to reason, which always became extravagant when it wanted to proceed speculatively with its ideas, and changes its transcendent use into an immanent use (in which reason is by means of ideas itself and efficient cause in the field of experience)”. (548)


Kant has established the validity of an objective moral principle with respect to its causality and by means of a law that cannot be regarded as natural. Hence, he claims[4] to have extended our cognition beyond the boundaries of the experience, inasmuch we can design positively freedom, but not what it is, or what it is content, since we do not have any intuition of it. It is important, though, that we remember that freedom is real from the standpoint of the transcendental idealism of the first Critique, that is, freedom of a transcendental idea. This is said to show the difference between some metaphysical realists previous to Kant and Kant himself. He will not claim to have discovered a way to prove the actuality of freedom in all ways, as an existing object, but only as a transcendental ground for practical purposes, that is, as an unmoved mover of human will.






-On the application of all pure categories and supersensible beings in a practical use-



In Kant’s opinion one last question needs to be answered, and it will be so tackled in the epigraph entitled “On the warrant of pure reason in its practical use to an extension which is not possible to it in its speculative use”. The question is “How, then, is the practical use of pure reason here to be united (vereinigt, perhaps “reconciled”) with its theoretical use with respect to determining the boundaries of its competence?” (5:50)


The path taken by Kant to answer this question is apparently aberrant. He dedicates five pages – from 5:50 to 5:55- to explain Hume’s critique of causality and to refute it. This refutation had already been done in the first Critique, therefore at a first glance, it seems unnecessary to return to this topic. However, one of the more powerful reasons that has given birth to the need of transcendental freedom is his belief in a mechanistic, Newtonian nature. So, now, since he has considered the necessity of grounding freedom into the concept of causa-noumenon, Kant finds himself in need of justifying his Newtonian, mechanistic version of nature in this new scheme.


Therefore, Kant accepts Hume’s claim in one sense: if appearances were considered as things in themselves, Hume would be right. The necessity of natural causality can nevertheless be known only a priori, for otherwise we would only have intuitions of a particular connection of two events. Hume, then, would say that since we cannot have any experience of such a necessity, the concept of causality is a mere illusion. And this conclusion drives philosophy to a radical skepticism: “of no event could one say; something must have preceded it, upon which it necessarily followed, that is, it must have a cause”. (5:51)


However, as Kant had stated in the first Critique, the objects with which we have to do in experience “are by no means things in themselves but only appearances” (5:53) and therefore, “it can be very well thought that as appearances they must necessarily be connected in one experience in a certain way (i.e. with respect to temporal relations) and cannot be separated without contradicting that connection by means of which this experience is possible”. (5:53)


However, what Kant really needs here is to be able to secure causality as a concept a priori in order to apply it to the noumenal world with a practical purpose. And this is something that he already did through the pure categories of the understanding and the pure concept of causality. [5]


In order to apply the concept of causality to things in themselves, Kant needs to a) save its validity (something that he did in the first Critique) and b) draw the boundaries for its practical use – to prove that it is right to use it in that context.


Since the concept of causality arises from the world of pure understanding, it can be stated a priori, and can therefore be applied to noumena even if it does not extend our theoretical knowledge. It is clear here that what Kant is trying to say is that the fact that this concept can be thought in a supersensible world opens the door to its use in the practical use of reason. It will not help us to attain any additional knowledge, but it will at least allow us to cognize the positive reality of freedom. Now the concept of a being  that has free will is the concept of a causa-noumenon…, (and) being in its origin independent of all sensible conditions and so itself not restricted to phenomena (unless one should want to make a determinate theoretical use of it), the concept could certainly be applied to things as beings of the pure understanding”. (5:55) Now the door is open to apply the concept of causality to supersensible beings, as along as it has something to do with the moral law, the free will, transcendental freedom and practical reason. Kant is proud of being authorized to do so by virtue of a ”pure, not empirical origin of the concept of cause, inasmuch as I consider myself authorized to make no other use of it than with regard to the moral law which determines its reality, that is, only a practical use”. (5:56) So, everything, even supersensible nature, is subject to causality, what matters here is its source.


The main point here is the distinction of the practical use and the theoretical use of the concept. One could claim that this was the main pint of all this section of the 2nd Critique. He insists once and again in the idea of the emptiness of this causa-nomenon in a theoretical sense, but it nonetheless has a “real application which is exhibited in concreto in dispositions or maxims, that is, it has practical reality which can be specified; and this is sufficient to justify it even with regard to noumena”.  (5:56)


This distinction will open the door for the grounding of all his metaphysics of morals. A grounding of a metaphysical system through the moral law that seemed to be lost forever at the end of the 1st Critique. Through the securement of the concept of causa-noumenon he has created a possibility for the securement of all other pure categories and, by analogy, of all supersensible beings and transcendental ideas including God and immortality; that is, a securement of a metaphysics of morals:


But this objective reality of a pure concept of understanding in the field of the supersensible, once introduced, gives all the other categories objective reality as well, though only insofar as the stand in necessary connection with the determining ground of the pure will (the moral law)- an objective reality which is, however, of only practical applicability and has not the least influence on theoretical cognition of these objects, as insight into their nature by pure reason, so as to extend this. (…) This are without exception to be counted not as knowledge but only as a warrant (for practical purposes, however, a necessity) to admit and presuppose them, even where supersensible beings (such as God) are assumed by analogy, that is, by purely rational relation of which we make a practical use with respect to what is sensible, and so, by this application to the sensible but only for practical purposes, pure theoretical reason is not given the least encouragement to fly into the transcendent.  (5:57)




Clearly, the result of this 2nd Critique, in what concerns to the deduction of freedom, was already in Kant’s mind when he began to write the 1st. Furthermore, in this deduction of freedom from the perspective of practical reason lies the basis for a metaphysics that he will build up throughout the rest of this 2nd Critique. The legitimacy of this return to metaphysical thinking is problematic not only because he had abandoned all metaphysical hopes in the 1st one, but also, and overall, because there are severe problems as to the compatibility of the two thesis that are assumed in both Critiques; i.e.: the simultaneous affirmation of the finitude of reason and the absoluteness of freedom. Either we admit that human beings can measure their reason as finite, because they participate to some extent in infinite reason and truth – and so nothing prevents him from enjoying an instant of absoluteness in his freedom- or, if reason is declared radically finite, then freedom would have also to be declared as finite and non-absolute. If faced with this problem, maybe Kant would say that nothing too safe could be said about this issue, and in fact he explicitly says at one point: ·I do not claim to know theoretically by this concept the constitution of a being insofar as it has a pure will; it is enough for me to thereby only designate it as such a being and hence only to connect the concept of causality with that of freedom”. (5:56) However, the distinction between the theoretical use and the practical use of reason -and so the duality of the self- as well as the positive determination of the idea of freedom as the ground on which the moral law is stated as an a priori proposition imply a recourse to “omniscience”, an “over-reasoning reason and a supersensible experience that he calls a “fact of reason”. That is, they imply a degree of belief.



[1] Hereafter all internal citations are to the English translation taken from Critique of Pure Reason, translated and edited by Werner S. Pluhar (Indianapolis/Cambridge Hacket Publishing Company, Inc., 1996)  

[2] Hereafter all internal citations are to the English translation taken from Critique of Practical Reason published in the collection, Cambridge Texts in the History of Philosophy, translated and edited by Mary Gregor (Cambridge, Cambridge University Press, 1997)

[3] parenthesis added by me

[4] 5:50

[5] “I was able not only to prove the objective reality of the concept of cause with respect to objects of experience but also to deduce it as an a priori concept (…) to show its possibility from pure understanding without empirical sources (5:53)


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