The Critique of Practical Reason

Metadata

Gutenberg ID

5683

Title

The Critique of Practical Reason

Language

en

Book source

Project Gutenberg

Description max 80 words

Kant's seminal work establishes the reality of pure practical reason, proving the existence of freedom through the moral law. It argues that while speculative reason cannot know the supersensible, practical reason necessitates the postulates of God, immortality, and freedom to achieve the summum bonum, elevating human worth beyond mere animality.

Summary up to 500 words

In *The Critique of Practical Reason*, Immanuel Kant undertakes a critical examination of the practical faculty of reason, distinguishing its speculative use, which deals with phenomena, from its practical use, which addresses the noumenal realm of freedom. The work establishes that the moral law serves as the *ratio cognoscendi* of freedom, meaning our consciousness of duty reveals our freedom, while freedom itself is the *ratio essendi* of the moral law. Kant defines true morality not merely as legality (acting in accordance with the law) but as acting from duty, where the sole motive is respect for the law, excluding all inclination. This distinction guards against moral fanaticism and the delusion of spontaneous goodness, emphasizing that finite rational beings must obey the law through constraint rather than mere love. The text resolves the antinomy of practical reason by asserting the primacy of practical reason. To make the *summum bonum* (the highest good, a union of virtue and happiness) possible, practical reason requires the postulates of God and immortality. These are not theoretically provable but are necessary assumptions for the application of a morally determined will to its object. The work culminates in its famous conclusion, asserting that two things fill the mind with awe: the starry heavens above and the moral law within. While the former view of the cosmos diminishes human importance as an animal creature, the latter elevates human worth as an intelligence. The moral law reveals a personality independent of the sensible world, granting a life of true infinity. Kant argues that science must critically examine reason to avoid the errors of crude judgment and the extravagances of genius, ensuring that the pursuit of wisdom remains grounded in a methodical understanding of the human capacity for freedom and moral duty.

LLM editorial rating

4.2/5

Download URL

https://www.gutenberg.org/ebooks/5683.epub.noimages

Local file path

data/epubs/pg5683.epub

Removed after upload

Downloaded at

2026-07-06 11:11 UTC

Categories

• Philosophy
• Ethics