Critique of Practical Reason

from Wikipedia, the free encyclopedia

Critique of Practical Reason ( KpV ) is the title of Immanuel Kant's second major work ; it is also referred to as the “second critique” (after the critique of pure reason and before the critique of judgment ) and was first published in 1788 in Riga.

The KpV contains Kant's theory of the justification of morality and is still considered to be one of the most important works of practical philosophy .

Like the Foundation for the Metaphysics of Morals , which appeared three years earlier, the KpV is a foundation document that does not deal with the practical application of the principles of morality, but rather answers the question of how human action can be determined by practical reason. The main aim of the KpV is to establish the basic principle of morality, its tasks and limits. Kant's views on practical moral philosophy can be found in the Metaphysics of Morals and in his lectures on moral philosophy

Outline of the work

The structure of the work is based on the structure that Kant had already used in the Critique of Pure Reason. After a preface and an introduction, there are two main parts. The "elementary theory of pure practical reason" and the "methodological theory of pure practical reason". In the elementary theory Kant again distinguishes between the analytics and the dialectics of pure practical reason. In analytics, Kant develops his theoretical position. He first outlines the principles, then he analyzes terms and finally he deals with the non-empirical “driving forces” of morality. The dialectic is then the "representation and resolution of appearances in judgments of practical reason" (KpV, 16). The second part, the methodology, comprises only 12 of the 163 pages that make up the work in the academy edition. Here Kant outlines a theory of moral education. At the end of the KpV there is the "decision" with the famous quote:

“Two things fill the mind with ever new and increasing admiration and awe, the more often and longer the reflection occupies itself with it: the starry sky above me, and the moral law in me. I am not allowed to look for either of these as veiled in darkness or in exuberance, outside of my field of vision, and merely guess; I see them in front of me and link them directly to the awareness of my existence. "(KpV 161/162)

Practical reason

The concern of the KpV is to answer the second big question of common sense: What should I do? - In contrast to the question of what we can know, Kant's practical philosophy has the question of good behavior as its subject.

First, Kant shows that freedom and autonomy are possible. Although the idea of ​​freedom cannot yet be “recognized” at the beginning of the train of thought, it makes sense to “accept” freedom. In the course of the train of thought, the provisionally assumed freedom is then shown to have a basis in the moral law.

If the will does not determine itself autonomously , man is unfree, since he is then guided by instincts and passions (or foreign domination). This difference between duty and inclination is central to the KpV. Moral duty is the basis of freedom.

The categorical imperative

Kant derives the principles of morality directly from human reason instead of from a divine prescription. The core of the KpV is the doctrine of the categorical imperative, which, as a characteristic of morality , embodies the strict generalizability of personal principles of action ( maxim ). The categorical imperative is also called the moral law or moral law by Kant, in the KpV he calls it the "Basic Law of Pure Practical Reason" and formulates:

"Act in such a way that the maxim of your will can also apply at any time as the principle of general legislation."

- § 7 Basic Law of Pure Practical Reason in the KpV, p. 54

Morally good action, according to Kant, is action according to the categorical imperative. As a rational being, man is free and can act according to the principles of reason. This ability is able to overcome instinctive and pleasure-led action as well as action based on pragmatic or tactical motives.

Derivation of the moral law

The principles of practical reason are either subjective maxims that can claim validity for one's own will , or objective laws that are authoritative for every reasonable will. If reason itself completely determines the will, the objectively necessary principle derived from it is a categorical imperative.

Subjective determinations of the will of the ability to desire have an empirical character, because their origin is the sought-after subjective relationship to the object of reality. In accordance with these provisions of will, it is not possible to establish an obligation that is valid for everyone in the form of a general law. Practical, generally applicable laws of pure reason, the objective necessity of which is recognized a priori , can therefore relate solely to a merely formal determination of the will. Pure reason compels the will, free of all causality, to commit itself to a general law, the moral law. The mere form of general legislation determines the autonomous will.

As an autonomous rational being, man has the ability to directly know his will and, in practical reason, rises above his empirical character and his dependence on the outside world. He is free to act according to moral principles.

Main expenses

  • Immanuel Kant: Critic of Practical Reason. Johann Friedrich Hartknoch , Riga 1788, digitized and full text , in the German text archive . (292 p., Erlangen reprint 1984).
  • Immanuel Kant: Critique of Practical Reason . In: Immanuel Kant: Critique of Practical Reason. Critique of Judgment . Edited by Paul Natorp . Georg Reimer, Berlin 1908 (= Kant's collected writings . Published by the Royal Prussian Academy of Sciences, 1st section, 5th volume), pp. 1–163.
  • Immanuel Kant: Critique of Practical Reason. Edited by Joachim Kopper, Reclam, Stuttgart 1961 and others. (= Reclams Universal Library No. 1111-13, later No. 1111).
  • Immanuel Kant: Critique of Practical Reason. Edited by Horst D. Brandt and Heiner F. Klemme, Meiner, Hamburg 2003, ISBN 3-7873-1650-7 (= Philosophical Library 506).


  • Theodor W. Adorno : Problems of moral philosophy . Frankfurt am Main 1996, ISBN 3-518-58225-9 .
    (In this lecture from 1963, Adorno deals almost exclusively with the Kantian moral philosophy.)
  • H. Allison: Kant's Theory of Freedom , Cambridge University Press 1990.
  • Karl Ameriks: Interpreting Kants Critiques , Oxford 2003.
  • M. Baron: Kantian Ethics Almost without Apology , Cornell University Press 1995.
  • LW Beck: Kant's Critique of Practical Reason , Munich 1974.
  • Robert J. Benton: Kant's Second Critique and the Problem of Transcendental Arguments , The Hague: Martinus Nijhoff 1977.
  • Paul Guyer: Kant and the experience of freedom . Essays on aesthetics and morality, Cambridge / New York 1993.
  • Thomas E. Hill, Jr. (Ed.): The Blackwell Guide to Kant's Ethics , Malden, MA 2009.
  • Otfried Höffe (ed.): Immanuel Kant: Critique of practical reason. Berlin 2002.
    (consistent commentary in essays by renowned experts)
  • Chr. M. Korsgaard: Creating the Kingdom of Ends , Cambridge 1996.
  • Phillip Stratton Lake: Kant, Duty and Moral Worth , Routledge: London 2000.
  • Giovanni B. Sala : Kant's 'Critique of Practical Reason'. A comment. Darmstadt 2004, ISBN 3-534-15741-9 .
    (First continuous commentary in German, explanations very close to the text, demanding)
  • Klaus Steigleder: Kant's moral philosophy . The self-referentiality of pure practical reason, Stuttgart 2002.
  • Dieter Sturma / Karl Ameriks (eds.): Kants Ethik , Mentis, Paderborn 2004.
  • Allen W. Wood: Kant's Ethical Thought , Cambridge 1999.
  • Allen W. Wood: Kantian Ethics , Stanford University, California 2007.

See also

Web links

Individual evidence

  1. Printed in the Academy Edition , Volume XXVII
  2. ^ KpV, preface p. 6 of the first edition
  3. page number of the first edition Riga 1788; here taken from: Immanuel Kant: Critique of Practical Reason. Edited by Horst D. Brandt and Heiner F. Klemme, Meiner, Hamburg 2003, ISBN 3-7873-1700-7 , p. 41.