Critique of Pure Reason
Kant's work seeking the limits and scope of metaphysics.
Immanuel Kant’s *Critique of Pure Reason* (first published in 1781, with a revised second edition in 1787) seeks to define the boundaries and potential of metaphysics. Kant explains that his “critique” examines the faculty of reason itself, focusing on all knowledge that reason strives to attain independently of any experience, in order to decide whether metaphysics is possible or impossible. The work engages with both empiricist thinkers like John Locke and David Hume, and rationalists such as René Descartes, Gottfried Wilhelm Leibniz, and Christian Wolff. Kant addresses Hume’s skepticism about cause and effect, as well as Descartes’ doubts regarding knowledge of the external world, through his doctrine of transcendental idealism. This view holds that objects are mere appearances, not things in themselves, and that space and time are only sensible forms of human intuition, not conditions of objects as they exist independently. By arguing that objects as appearances must conform to our cognition, Kant establishes the possibility of a priori knowledge—knowledge independent of experience. He distinguishes a priori propositions as necessary and universal, while a posteriori knowledge, gained through the senses, lacks absolute necessity. Kant also differentiates analytic judgments, where the predicate is contained within the subject, from synthetic judgments, where the predicate adds new content. Before Kant, it was assumed all a priori knowledge was analytic; he argues instead that mathematics, natural science, and metaphysics rest on synthetic a priori judgments. The central problem of the *Critique* is thus to explain how such judgments are possible. Initially overlooked, the book later sparked controversy among empiricist and rationalist critics, profoundly influenced Western philosophy, and helped launch German idealism, marking both a culmination of early modern thought and the start of late modern philosophy.
- Full title
- Critique of Pure Reason
- Author
- Immanuel Kant
- Field
- Philosophy
- Language
- German
- Known for
- Determining the limits and scope of metaphysics; introducing synthetic a priori judgments
Quick Facts
- Title Orig
- Critik der reinen Vernunft
- Orig Lang Code
- de
- Translator
- see below
- Author
- Immanuel Kant
- Country
- Riga, Riga Governorate, Russian Empire
- Publisher
- Johann Friedrich Hartknoch
- Language
- German
- Subject
- Metaphysics
- Published
- 1781
- Pages
- 856 (first German edition)
- Notes
- a Kritik in modern German.
- Native Wikisource
- Critik der reinen Vernunft (1781)
Facts from the source article.
Lore & Background
In the preface to the first edition, Kant explains that by a "critique of pure reason" he means a critique "of the faculty of reason in general, in respect of all knowledge after which it may strive independently of all experience" and that he aims to decide on "the possibility or impossibility of metaphysics". Kant argues through transcendental idealism that objects are mere representations and not things in themselves, and that their form of appearance consists only of sensible forms of our intuition. This grants the possibility of a priori knowledge, since objects as appearance must conform to our cognition. Kant distinguishes between analytic and synthetic judgments. A proposition is analytic if the predicate-concept is already contained within the subject-concept; for example, "All bodies are extended" is analytic. A proposition is synthetic if the predicate-concept is not contained within the subject-concept, as in "All bodies are heavy". Before Kant, philosophers held that all a priori knowledge must be analytic. Kant, however, argues that knowledge of mathematics, first principles of natural science, and metaphysics is both a priori and synthetic. The central problem of the Critique is therefore to answer the question: "How are synthetic a priori judgments possible?"
Reader's Guide
The Critique of Pure Reason is considered a culmination of several centuries of early modern philosophy and an inauguration of late modern philosophy. Though it received little attention when first published, it later attracted attacks from both empiricist and rationalist critics and became a source of controversy. It has exerted an enduring influence on Western philosophy and helped bring about the development of German idealism. Kant's work was stimulated by his decision to take seriously Hume's skeptical conclusions about basic principles such as cause and effect, which had implications for Kant's grounding in rationalism. Kant rejected analytical methods for deriving cause and effect, arguing that analytic reasoning cannot tell us anything not already self-evident, and sought to demonstrate how synthetic a priori knowledge is possible. This question is central because Kant contends that all important metaphysical knowledge is of synthetic a priori propositions; if it is impossible to determine which such propositions are true, then metaphysics as a discipline is impossible.
Did You Know?
- Kant explains that by a 'critique of pure reason' he means a critique of the faculty of reason in respect of all knowledge after which it may strive independently of all experience.
- Kant uses the example '7 + 5 = 12' to argue that pure mathematics is synthetic though a priori, since no analysis of 7 or 5 will find 12.
- The work was set down in written form in just four to five months, while Kant was also lecturing and teaching, but is a summation of twelve years of philosophical development.
- Kant states that it was the remembrance of David Hume which first interrupted his 'dogmatic slumber' and gave his investigations a completely different direction.
Frequently Asked Questions
What is Critique of Pure Reason?
It is a landmark philosophical work by Immanuel Kant, written in German, that examines the limits and proper scope of metaphysics. The text introduced the concept of synthetic a priori judgments and remains one of the most widely studied works in the history of Western philosophy.
What problem does Critique of Pure Reason aim to solve?
Kant set out to counter the skepticism David Hume raised about cause and effect, as well as René Descartes' doubts about whether we can truly know the external world. The book proposes a new account of the nature of space and time to resolve these challenges.
Which earlier thinkers influenced Critique of Pure Reason?
The work draws on the empiricist tradition of John Locke and David Hume alongside the rationalist tradition of René Descartes, Gottfried Wilhelm Leibniz, and Christian Wolff. Kant synthesizes and moves beyond both camps to build his own framework for understanding human knowledge.
What is Kant's key contribution in Critique of Pure Reason?
Kant introduced the notion of synthetic a priori judgments, arguing that some knowledge is both genuinely informative and universally necessary without relying solely on sensory experience. He also laid out a systematic determination of what metaphysics can legitimately claim to know.
Why is Critique of Pure Reason considered so important?
It fundamentally reshaped how philosophers think about the relationship between the mind and the world, offering a framework that transcends both pure empiricism and pure rationalism. Its analysis of space, time, and the architecture of human understanding continues to anchor debates in epistemology and metaphysics to this day.
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