Kind of moral law in criticism of practical reason

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NETO, Silvio Couto [1], CANDIOTTO, Cesar [2]

NETO, Silvio Couto. CANDIOTTO, Cesar. Kind of moral law in criticism of practical reason. Revista Científica Multidisciplinar Núcleo do Conhecimento. Year 05, Ed. 12, Vol. 01, pp. 87-97. December 2020. ISSN: 2448-0959, Access link:


In the present work, we intend to make an approach on the issue of the type of moral law as treated by Immanuel Kant in his work Critique of Practical Reason, seeking an explanatory approach rises to this point and, in what is shown possible, a comparison to the criminal type, used in the theory of criminal law; this is because the type of moral law has a purpose similar to the type of moral law, that is, to enable the understanding of the law. The moral law – which is totally free from the influence of any natural, sensitive element, dictated solely by free reason and a priori, without external constraints – can be understood, from the type through existing models in the natural world, phenomenal, elements, therefore, concrete and sensitive.

Keywords: practical reason, maximal, moral law, moral type, Kant.


Immanuel Kant, born in Prussia (present-day Germany) on 22 April 1724, is one of the best known and respected thinkers in the history of philosophy, and an icon of modern philosophy; this thinker was able to delimit the limits of reason at the time he lived, performing a synthesis between Rationalism and Empiricism. Kant’s philosophy demonstrates what reason may or may not know, from a critical posture, overcoming the then existing dichotomy among the schools mentioned (empiric and rationalist). To this do so, the Prussian thinker investigates what the rational human being is capable of knowing; what you must do to achieve this knowledge; what can you expect (in an analysis of hope, or even of the human relationship with religion); and finally what is the human being. This last question ends up being a union of the first three questions and, therefore, a fundamental question.

Kant’s complex thinking, however, is not easy to understand, requires intense study and reflection in order to reach its depth and acuity. Thus, this work aims to collaborate with this task, adding to the other studies already existing on Kantian philosophy, especially, seeking to shed some light on the issue of the type of moral law in the form treated by Immanuel Kant in his work Critique of Practical Reason (2016).

In 1781 Kant published the Critique of Pure Reason, – perhaps the most famous work of this philosopher – in which he analyzes reason, in its characteristic of subjectivity and ability to understand the phenomena that present themselves to it through the senses and that, in this way, would be his objects of knowledge. On the other hand, in a metaphysical analysis, it studies what it calls the nuptum, which never present itself to the senses, but emerge from pure thought; understands that the numenos can also be the object of metaphysical reason. In the words of Bonaccini (2012, p. 73), “Metaphysics has always raised the pretension to knowledge beyond experience (that is, to a priori, purely rational knowledge)”.

This Kantian work – Critique of Pure Reason – in short, analyzes what reason is capable, what it may or may not know and how it can do it. By criticism, it considers how knowledge itself can be understood and, through transcendental dialectics, allows ideas that do not have possible aspects of being captured by the senses, it is worth saying, that they do not present themselves to the appreciably to thought, can also be known. Thus, for example, the idea of God or soul does not present itself to the senses, but raises questions; such questions cannot be answered by the criterion of reason, but can be analyzed through the use of transcendental dialectics, opening this space, even, for the use of faith.

On the other hand, the work that is directly linked to the object of this text, The Critique of Practical Reason, has an approach linked to ethical issues, was published in 1788, therefore, later that commented above. In this work, Kant states that, free from the conditions that limit knowledge, the human being must deduce the ethical principles of his own reason, which will thus be necessary, universal and unbound from personal or cultural feelings. Such principles shall be universally imposed on all, at any time and in any condition; practical reason, in such a way, acquires a law-giving character, grants the moral law. Perin (2018, p. 202) states verbatim that

What Kant takes for granted in the Critique of practical reason by conjecture a methodological strategy for the justification of the practical use of reason is that it can no longer be undertaken through a passage between the theoretical and practical domains. Thus, both the proposal and the unfolding and, also, the result of the argumentation of this work support precisely the need that in the practical domain itself be legitimized an unconditional practical legislation and, also, that the constitutive consequences of this legitimation undertaking have their validity restricted to the intrinsic scope to the same domain.

Thus, in the context of the use of practical reason, and in its legislative aspect, Kant refers to the question of the type of moral law, which is intended to explain or, at least, facilitate its correct understanding, using a reasoning that uses a reverse analogy to the type of criminal law.


To reach the desired point in this text, a quick exposition on the logical antecedents regarding the type of moral law and the moral law itself, contained in the Critique of Practical Reason, is indispensable, under penalty of becoming incomprehensible the point to those who do not have any familiarity with the subject.

In the exquisite work mentioned above – Critique of Practical Reason, Kant exposes and analyzes the possibility of the practical use of reason, dispensing, and even, refusing the influence of any empirical, sensitive condition, for its formation; in this function reason is legislator and thus author of the moral law.

The thinker in analysis demonstrates that reason, in its practical use, is responsible for the general determination of the will of the rational being. Being connected to the faculty of desire, the reason considered as intention is not always universal. Kant demonstrates that this will of the rational being, in turn, will be determined by principles, which will give rise to maxims, that is, subjective rules, valid only for the will of a given subject. Highs or hypothetical imperatives are therefore principles, but are not imperative.

The will conditioned by practical reason may also give way to laws, which are objective, universally valid and must guide the will of every rational being, regardless of the subjective conditions that distinguish each of these beings. These laws will always be practically correct, and will therefore be categorical, and should always, it is reiterated, guide the will of the rational being, regardless of the causal possibility of obtaining, in practice, a certain desired effect, since the final result belongs to the sensitive world and should not be considered for this evaluation. In the words of Perin (2018, p. 212), “Kant argues that practical legislation, provided that it is unconditionally decisive of the will and thus valid for rational beings in general, can only be conceived as autonomy of will”.

The categorical imperative for Kant is unconditioned, requiring that one always act according to moral law (whereas, the hypothetical imperative would be that conditional, when a certain effect is desired). Thus, as Ribeiro (2019, p. 32) states,

Kant argues that practical legislation, provided that it is unconditionally decisive of the will and thus valid for rational beings in general, can only be conceived as autonomy of the will, that is, as ‘[…] that his property thanks to which it is for herself his law (regardless of the nature of the objects of the will)’.

Continuing his reasoning, Kant demonstrates that pleasure or displeasure, the pleasure of life, are subjective and cannot be known a priori, therefore, the principle that is based on this subjective condition may be a maxim, but never a law.

The material practical rules that give rise to desired abilities, such as pleasure or displeasure, are inferior, being necessary the exclusively formal constraints of the will to arise the possibilities of desiring superior, without any interference of the pleasant or unpleasant, pleasure or displeasure. In Kant’s words, without being subordinated to the “faculty of pathologically determinable desire”. (KANT, 2016, p. 41).

Of all it is concluded that, for Kant, only pure practical reason, without the interference of any feelings, can be legislator. The philosopher also states that only the free will, it is worth saying, the freedom of the will to obey only the moral law, without any empirical conditioning, of phenomena and external causality, can be considered what he calls transcendental freedom.

It states that the knowledge of the unconditionally practical cannot, however, begin with the knowledge of freedom, because the finite rational being is not immediately aware of this freedom, on the contrary, it begins with the creation of maxims, therefore, personal determinations, which present themselves primarily to the individual and that reason makes us realize that they cannot be overcome by any sensitive condition, of which they are independent and , thus showing itself in the condition of reaching the level of moral law. Only then does reason make you realize that you have the freedom to act according to moral law.

As the claim of Kantian legislation is universality, an excerpt from the work under study is considered one of the best examples of the aforementioned categorical imperative. This utterance, which has no material content, but only formal horizon is the one that states: “Act so that the maxim of your will can always be valid at the same time as the principle of universal legislation.” (KANT, 2016, p. 49).

Thus, reason as a pure will, without any conditioning, without the aid of experience or external will, which determines the a priori will by the form of its maxims, is legislator.

The awareness of this fundamental law, which imposes itself as a synthetic proposition a priori, which is not founded on any intuition” can be called, according to the author, a fact of reason. And he complements the philosopher by asserting that it is a fact of pure reason that is announced as originally a legislator. (KANT, 2016, p. 51).

This pure practical reason, according to Kant, provides man with a universal law that was spoken above, which he calls a moral law, valid for all rational beings capable of determining their causality through the consciousness of rules; moral law is therefore a categorical imperative. In this condition, the categorical imperative is unconditioned in relation to man, who has, in relation to him, a bond of obligation, of duty, in order to seek to approach, in infinite progress, what Kant calls holy will. This categorical imperative will guide its maxims, in search of virtue, the highest point that can be reached by the finite rational being.

The production of moral law by pure practical reason is the demonstration of autonomy, of pure will, of freedom in the positive sense, in which all the maxims produced by the individual come in line with the practical law.

On the contrary, if in the production of their maxims the individual lets influence any theme related to desire, by wanting, will contaminate its maxims by heteronomy, it is worth saying, removing the purity of its maxims, which will not then create any obligation, on the contrary, will be opposed to moral law.

Kant cites as an example that not even the happiness of other beings, the happiness of all, can be placed as a condition of a maxim, without resaking its autonomy and preventing it from becoming law; this is the case, because it would depend on an object to be sought in empirical conditions, it would depend on the experience and opinion of each individual, and thus cannot apply objectively to a necessary and universal rule. As the maximum advises, the moral law commands and obedience this command is always within reach of the possibility of all rational beings.

In deducing the principles of pure practical reason, the author demonstrates that the world of nature is always governed by laws and is divided into two spheres: the supersensitive, which would be an archetypal nature, existing under the autonomy of pure practical reason, regardless of empiricism, whose maximum law is moral law, which, however, its equivalent must exist in the sensitive world, in the sensitive nature of beings , governed by empirically conditioned laws, or thromasons containing the effect of the former, the ectypic nature.

Thus, idealistically, if the physical capacity existing in the sensitive world were adequate, obedience to the moral law would produce the high well[3].

Continuing in his lessons, Kant demonstrates that practical reason is the possibility of representing an object, as a possible effect of freedom, the possibility or impossibility of wanting the action by which the object would be made possible in the absence of capacity to do so. This physical capacity to obtain the object is indifferent, the important thing is to know if the moral law authorizes us to want this object, so that the foundation of determination is not the object, but the moral law.

In this way, the only possible objects of a practical reason are good and evil. Good as a necessary object, for it is not possible to reason not to want good and, second, evil, only as a denial of good. And this good should be good in itself, regardless of judgment of good consequences, which is restricted to perception by the feelings of individual subjects. In other words, for Kant good cannot be mere consequence, but created by volitional freedom.

This good, therefore, must be determined by the autonomous will because

the law immediately determines the will, the action that is according to the law is good in itself, and a will whose maximum is always according to this law, is absolutely good, in all purposes, and is the supreme condition of all good. (KANT, 2016, p. 90) – Original griffins.

He goes on to explain that good and evil are modes of a single category, that of causality, a true demonstration of the freedom of reason, which is thus proven to be practical.


After the above, where it was intended to introduce Kant’s thought about the moral law, in a very esquematic and without pretension of great depth, just to allow some understanding to those who do not know the work analyzed, we now seek, also with a purpose of illustrative exposition, to address the issue of the type of moral law as treated by the author in the Critique of Practical Reason.

Before analyzing the author’s lessons on the issue, a parallel is used here as a means of simplified explanation; it is, therefore, to use the concept of type used in criminal doctrine, therefore, of criminal type, to seek to facilitate the understanding of the type of moral law in Kant.

They are, of course, different things. The kind of moral law seeks to allow the understanding of the commandment for an approximation of the achievement of the good, dictated exactly by the moral law, emanating from pure and free reason; on the contrary, the criminal type, emanating from the positive legal system, has the scope to fix and clarify the conduct prohibited by criminal law at a certain time and place. It is believed, however, that comparative analysis may be somehow feasible for purely didactic purposes, facilitating understanding of the type of moral law.

To this end, it is recalled that the criminal type is, roughly, an abstract proposition, an abstract rule, to which a certain concrete conduct may eventually become subsumed, thus perfecting the figure of the illicit that was, it is reiterated, only abstractly in that contained rule. It serves, therefore, to understand the commandment contained in the criminal law, which is in a normative world and that can be realized in the sensitive universe.

In other words, the criminal type is the legal provision and the reasonably accurate description of a prohibited conduct, which can sometimes be simpler or more complex, with all the elements and circumstances of that conduct, which, however, are not the conduct in itself; on the contrary, it is a mere legal description of a possible conduct, which exists only in concept and ideally, not concretely. Thus, the criminal type is the “legal norm prescribes [what] imperatives of the duty to be defined in the form of prohibitions, warrants and permissions of actions directed at human beings” (SANTOS, 2017, p. 58).

Human conduct may eventually be opposed to practicing commanded actions or, on the contrary, by exercising prohibited actions, to adapt, now in concrete, to that rule that once existed in the abstract, improving, then, the typical fact.

In a similar way – although with the difference in fundamentals already mentioned before – moral law has only the free reason to give rise to it; this free reason, however, is not part of the world of sensitive nature and, even so, moral law should, at least idealistically, be applied to objects of that nature. As Kant exposes, the kind of moral law allows what was said in the universal rule, in abstract, to be observed in an object in concrete. In the words of Mathias Netto (2020, p. 105), the kind of moral law says, “Ask yourself if the action you project, in case it has to happen according to a law of nature that you yourself would be a part of, could still consider it possible by your will.”

In such a way, the type of moral law must enable the understanding of the finite rational being, through concrete objects – therefore, which are in the world of nature and that present themselves to the senses through their forms – what is commanded by the law. In this way, it can be said, in particular, that a Church can be taken as a type existing in nature that allows a better understanding of the idea of the law about good.

Just as in the criminal type the abstract description of the conduct is not the illicit in itself, also here, in the type of moral law, the possibility of subsuming a practical action or object of the world sensitive to a pure practical law, does not make the action effectively happen or is linked to the sensitive world, it is, in fact, only an illustration that facilitates understanding.

As Kant teaches,

the moral law has no other faculty of knowledge to mediate the application of this law to the objects of nature, other than understanding (not imagination), which can place under an idea of reason, not a scheme of sensitivity, but a law depending on the power of judging, and a law that can be presented in concrete in the objects of the senses and , therefore a law of nature, but only according to its form, and we can call it, therefore, kind of the moral law. (KANT, 2016, p. 98)

Thus, the application, use, or, to express more accurately, the observation of the type of moral law, facilitates the understanding by the human being, rational that is, of the commandment of this law, through the observation of concrete symbols.


With the present exposition and comparison of the concept of type of criminal law, appropriate in a squeematic way from the theory of the criminal type in the respective doctrine, with the type of moral law, from the form exposed by Kant in the Critique of Practical Reason, it was intended to facilitate the understanding of the latter.

This seems possible because there is a similarity between these types, even if inside out, starting the first – criminal type – from the abstract to illustrate the concrete and the second – type of moral law – making the opposite way, leaving the concrete and making it possible to achieve the idea contained in abstract reason.

The similarity between the comparative figures is, as demonstrated, that both lend themselves to representations. In the first case, the criminal type, has the character of using abstract symbols for the understanding of concrete; it is worth saying, the criminal law is based on abstract descriptions of human conduct to lead the interpreter to understand concrete situations that are subsumed to it. In the second case, in relation to the type of Kantian moral law, exactly an operation of inverse rationalization occurs: the rational human being must, from the observation of concrete symbols, existing objects in nature and captured by the senses, use them as models for the understanding of the abstract, that is, of moral law.


BONACCINI, Juan Adolfo. O argumento da estética e o problema da aprioridade: ensaio de um comentário preliminar. In: Comentários às obras de Kant: Crítica da Razão Pura. Joel Thiago Klein (Org.), Florianópolis: NEFIPO, 2012 – pp. 71 – 144.

KANT, Immanuel. Crítica da razão prática. Tradução de Monique Hulshof. Petrópolis: Vozes, 2016.

MATHIAS NETTO. Jayme. A função da imaginação: resolução da típica da lei moral em Kant. In: Polymatheia Revista de Filosofia, Universidade Estadual do Ceará – UECE, v. 6, nº. 9, 2013 – pp. 91 – 108.  Disponível em:  <>. Acesso em: 20 abr. 2020.

NASCENTES, Zama Caixeta. O sumo bem na filosofia prática de Kant. Orientador: Vinícius de Figueiredo. Dissertação (Mestrado). Universidade Federal do Paraná, Curitiba, 2004. Disponível em: <>. Acesso em: 14 fev. 2019.

PERIN, Adriano. Kant e a estratégia metodológica da crítica da razão prática. In: Revista Dissertatio de Filosofia, Universidade Federal de Pelotas-RS – UFPel, nº 29, Pelotas-RS, 2009 – pp. 201 – 225. E-ISSN 1983-8891. Disponível em: <>. Acesso em 18 out. 2018.

RIBEIRO, Elton Cândido. Kant e o fundamento da moralidade: um estudo da dedução do imperativo categórico em GMS III. Orientador: Mario Ariel González Porta. Dissertação (Mestrado). Pontifícia Universidade Católica de São Paulo – PUC-SP. Disponível em:>. Acesso em 27 abr. 2019.

SANTOS, Juarez Cirino dos. Direito penal: parte geral. 7ª ed. rev., atual. e ampl. Florianópolis: Empório do Direito, 2017.


3. It is important to note that the “good sumo”, for Kant, is, as Nascentes (2019, p. 8) mentions, “the possibility of the synthetic connection between happiness and morality, this as a condition of becoming worthy of that”

[1] Doctorate in progress from the Pontifical Catholic University of Paraná – PUC-PR, School of Education and Humanities – Graduate Program in Philosophy; Master’s degree in Applied Social Sciences from the State University of Ponta Grossa; Specialist in Criminal Procedural Law at PUC-PR and graduated in Law.

[2] Advisor. PhD in Philosophy. Master’s degree in Education. Improvement in Research. Graduation in Theology. Graduation in Theology.

Submitted: November, 2020.

Approved: December, 2020.

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PhD in progress by the Pontifical Catholic University of Paraná - PUC-PR, School of Education and Humanities - Graduate Program in Philosophy; Master in Applied Social Sciences by the State University of Ponta Grossa; Specialist in Criminal Procedural Law at PUC-PR and graduated in Law.


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