Immanuel Kant in the context of Critical philosophy

The Age of Enlightenment (also the Age of Reason) was a period in the history of Europe and Western civilization during which the Enlightenment, an intellectual and cultural movement, flourished, emerging in the late 17th century in Western Europe and reaching its peak in the 18th century, as its ideas spread more widely across Europe and into the European colonies, in the Americas and Oceania. Characterized by an emphasis on reason, empirical evidence, and scientific method, the Enlightenment promoted ideals of individual liberty, religious tolerance, progress, and natural rights. Its thinkers advocated for constitutional government, the separation of church and state, and the application of rational principles to social and political reform.

The Enlightenment emerged from and built upon the Scientific Revolution of the 16th and 17th centuries, which had established new methods of empirical inquiry through the work of figures such as Galileo Galilei, Johannes Kepler, Francis Bacon, Pierre Gassendi, Christiaan Huygens and Isaac Newton. Philosophical foundations were laid by thinkers including René Descartes, Thomas Hobbes, Baruch Spinoza, and John Locke, whose ideas about reason, natural rights, and empirical knowledge became central to Enlightenment thought. The dating of the period of the beginning of the Enlightenment can be attributed to the publication of Descartes' Discourse on the Method in 1637, with his method of systematically disbelieving everything unless there was a well-founded reason for accepting it, and featuring his dictum, Cogito, ergo sum ('I think, therefore I am'). Others cite the publication of Newton's Principia Mathematica (1687) as the culmination of the Scientific Revolution and the beginning of the Enlightenment. European historians traditionally dated its beginning with the death of Louis XIV of France in 1715 and its end with the outbreak of the French Revolution in 1789. Many historians now date the end of the Enlightenment as the start of the 19th century, with the latest proposed year being the death of Immanuel Kant in 1804.

German philosophy, meaning philosophy in the German language or philosophy by German people, in its diversity, is fundamental for both the analytic and continental traditions. It covers figures such as Gottfried Wilhelm Leibniz, Immanuel Kant, Georg Wilhelm Friedrich Hegel, Karl Marx, Friedrich Nietzsche, Martin Heidegger, Ludwig Wittgenstein, the Vienna Circle, and the Frankfurt School, who now count among the most famous and studied philosophers of all time. They are central to major philosophical movements such as rationalism, German idealism, Romanticism, dialectical materialism, existentialism, phenomenology, hermeneutics, logical positivism, and critical theory. The Danish philosopher Søren Kierkegaard is often also included in surveys of German philosophy due to his extensive engagement with German thinkers.

Christian Wolff (/vɔːlf/; less correctly Wolf, German: [vɔlf]; also known as Wolfius; ennobled as Christian Freiherr von Wolff in 1745; 24 January 1679 – 9 April 1754) was a German philosopher. Wolff is characterized as one of the most eminent German philosophers between Leibniz and Kant. His life work spanned almost every scholarly subject of his time, displayed and unfolded according to his demonstrative-deductive, mathematical method, which some deem the peak of Enlightenment rationality in Germany.

Wolff wrote in German as his primary language of scholarly instruction and research, although he did translate his works into Latin for his transnational European audience. A founding father of, among other fields, economics and public administration as academic disciplines, he concentrated especially in these fields, giving advice on practical matters to people in government, and stressing the professional nature of university education.

Arthur Schopenhauer (/ˈʃoʊpənhaʊər/ SHOH-pən-how-ər; German: [ˈaʁtuːɐ̯ ˈʃoːpn̩haʊɐ] ; 22 February 1788 – 21 September 1860) was a German philosopher. He is known for his 1818 work The World as Will and Representation (expanded in 1844), which characterizes the phenomenal world as the manifestation of a blind and irrational noumenal will. Building on the transcendental idealism of Immanuel Kant, Schopenhauer developed an atheistic metaphysical and ethical system that rejected the contemporaneous ideas of German idealism.

Schopenhauer was among the first philosophers in the Western tradition to share and affirm significant tenets of Indian philosophy, such as asceticism, denial of the self, and the notion of the world-as-appearance. His work has been described as an exemplary manifestation of philosophical pessimism. Though his work failed to garner substantial attention during his lifetime, he had a posthumous impact across various disciplines, including philosophy, literature, and science. His writing on aesthetics, morality and psychology has influenced many thinkers and artists.

A phenomenon (pl. phenomena), sometimes spelled phaenomenon, is an observable event. The term came into its modern philosophical usage through Immanuel Kant, who contrasted it with the noumenon, which cannot be directly observed. Kant was heavily influenced by Gottfried Wilhelm Leibniz in this part of his philosophy, in which phenomenon and noumenon serve as interrelated technical terms. Far predating this, the ancient Greek Pyrrhonist philosopher Sextus Empiricus also used phenomenon and noumenon as interrelated technical terms.

An unobservable (also called impalpable) is an entity whose existence, nature, properties, qualities or relations are not directly observable by humans. In philosophy of science, typical examples of "unobservables" are the force of gravity, causation and beliefs or desires. The distinction between observable and unobservable plays a central role in Immanuel Kant's distinction between noumena and phenomena as well as in John Locke's distinction between primary and secondary qualities. There is considerable disagreement about which objects should be classified as unobservable, for example, whether bacteria studied using microscopes or positrons studied using cloud chambers count as unobservable. Different notions of unobservability have been formulated corresponding to different types of obstacles to their observation.

In aesthetics, the concept of taste has been the interest of philosophers such as Plato, Hume, and Kant. It is defined by the ability to make valid judgments about an object's aesthetic value. However, these judgments are deficient in objectivity, creating the 'paradox of taste'. The term 'taste' is used because these judgments are similarly made when one physically tastes food.

Criticism of Christianity has a long history that stretches back to the initial formation of the religion in the Roman Empire. Critics have challenged Christian beliefs and teachings, as well as actions taken in the name of the faith, from the Crusades to modern terrorism. The arguments against Christianity include claims that it is a faith of violence, corruption, superstition, polytheism, homophobia, bigotry, pontification, abuses of women's rights, and sectarianism.

In the early years of Christianity, the Neoplatonic philosopher Porphyry emerged as one of the major critics with his book Against the Christians, along with other writers like Celsus and Julian. Porphyry argued that Christianity was based on false prophecies that had not yet materialized. Following the adoption of Christianity by the Roman Empire, dissenting religious voices were gradually suppressed by both governmental and ecclesiastical authorities. Christianity has faced significant theological criticism from thinkers of other Abrahamic religions, particularly including Judaism and Islam. Notably, Maimonides, the renowned rabbi, Jewish philosopher, and Torah scholar of the 12th century, argued that Christian practices and doctrines constituted idolatry and deviated from the strict monotheism (shituf) of Jewish and Muslim theologies. Similarly, Islamic scholars have critiqued Christian beliefs about the Trinity and the divinity of Jesus, viewing these concepts as incompatible with the concept of monotheism. These critiques reflect deep theological disagreements rooted in their shared scriptural traditions and divergent doctrinal interpretations. A millennium later, the Protestant Reformation led to a fundamental split in European Christianity and rekindled critical voices about the Christian faith, both internally and externally. In the 18th century, deist philosophers such as Voltaire and Jean-Jacques Rousseau were critical of Christianity as a revealed religion. With the Age of Enlightenment, Christianity was criticized by major thinkers and philosophers, such as David Hume, Thomas Paine, and the Baron d'Holbach. The central theme of these critiques sought to negate the historical accuracy of the Christian Bible and focused on the perceived corruption of Christian religious authorities. Other thinkers, like Immanuel Kant, offered critiques of traditional arguments for the existence of God, while professing to defend Christian theology on novel grounds.

George Berkeley (/ˈbɑːrkli/ BARK-lee; 12 March 1685 – 14 January 1753), known as Bishop Berkeley (Bishop of Cloyne of the Anglican Church of Ireland), was an Anglo-Irish philosopher, writer, and clergyman who is regarded as the founder of "immaterialism", a philosophical theory he developed which later came to be known as subjective idealism. He has also been called "the father of idealism" by German philosopher Arthur Schopenhauer. Berkeley played a leading role in the empiricism movement and was one of its pioneers. He was among the most cited philosophers of 18th-century Europe, and his works deeply influenced later thinkers such as Immanuel Kant and David Hume.

In 1709, Berkeley published his first major work An Essay Towards a New Theory of Vision, in which he discussed the limitations of human vision and advanced the theory that the proper objects of sight are not material objects, but light and colour. This foreshadowed his most well-known philosophical work A Treatise Concerning the Principles of Human Knowledge, published in 1710, which, after its poor reception, he rewrote in dialogue form and published under the title Three Dialogues Between Hylas and Philonous in 1713. In this book, Berkeley's views were represented by Philonous (Greek: "lover of mind"), while Hylas ("hyle", Greek: "matter") embodies Berkeley's opponents, in particular John Locke.

Praxis is the process by which a theory, lesson, or skill is enacted, embodied, realized, applied, or put into practice. "Praxis" may also refer to the act of engaging, applying, exercising, realizing, or practising ideas. This has been a recurrent topic in the field of philosophy, discussed in the writings of Plato, Aristotle, St. Augustine, Francis Bacon, Immanuel Kant, Søren Kierkegaard, Ludwig von Mises, Karl Marx, Antonio Gramsci, Martin Heidegger, Hannah Arendt, Jean-Paul Sartre, Paulo Freire, Murray Rothbard, and many others. It has meaning in the political, educational, spiritual and medical realms.

German idealism is a philosophical movement that emerged in Germany in the late 18th and early 19th centuries. It developed out of the work of Immanuel Kant in the 1780s and 1790s, and was closely linked both with Romanticism and the revolutionary politics of the Enlightenment. The period of German idealism after Kant is also known as post-Kantian idealism or simply post-Kantianism. One scheme divides German idealists into transcendental idealists, associated with Kant and Fichte, and absolute idealists, associated with Schelling and Hegel.

The German Enlightenment (German: die deutsche Aufklärung) refers to the intellectual and cultural movement that flourished in the 18th-century German states as part of the broader Enlightenment (historically known in German as die Aufklärung).

Prussia took the lead among the German states in sponsoring the political reforms that Enlightenment thinkers urged absolute rulers to adopt. There were important movements as well in the smaller states of Bavaria, Saxony, Hanover, and the Palatinate, although the Protestant regions were globally more active in the German Enlightenment than the Catholic ones. In each case, Enlightenment values became accepted and led to significant political and administrative reforms that laid the groundwork for the creation of modern states.

In philosophy, a noumenon (/ˈnuːmənɒn/, /ˈnaʊ-/; from Ancient Greek: νοούμενoν; pl.: noumena) is knowledge posited as an object that exists independently of human sense. The term noumenon is generally used in contrast with, or in relation to, the term phenomenon, which refers to any object of the senses. Immanuel Kant first developed the notion of the noumenon as part of his transcendental idealism, suggesting that while we know the noumenal world to exist because human sensibility is merely receptive, it is not itself sensible and must therefore remain otherwise unknowable to us. In Kantian philosophy, the noumenon is often associated with the unknowable "thing-in-itself" (German: Ding an sich). However, the nature of the relationship between the two is not made explicit in Kant's work, and remains a subject of debate among Kant scholars as a result.

Transcendental idealism is a philosophical system founded by German philosopher Immanuel Kant in the 18th century. Kant's epistemological program is found throughout his Critique of Pure Reason (1781). By transcendental (a term that deserves special clarification) Kant means that his philosophical approach to knowledge transcends mere consideration of sensory evidence and requires an understanding of the mind's innate modes of processing that sensory evidence.

In the "Transcendental Aesthetic" section of the Critique of Pure Reason, Kant outlines how space and time are pure forms of human intuition contributed by our own faculty of sensibility. Space and time do not have an existence "outside" of us, but are the "subjective" forms of our sensibility and hence the necessary a priori conditions under which the objects we encounter in our experience can appear to us at all. Kant describes time and space not only as "empirically real" but transcendentally ideal.

In late modern philosophy, neo-Kantianism (German: Neukantianismus) was a revival of the 18th-century philosophy of Immanuel Kant. The neo-Kantians sought to develop and clarify Kant's theories, particularly his concept of the thing-in-itself and his moral philosophy.

Adrian William Moore FBA (born 29 December 1956) is a British philosopher and broadcaster. He is Professor of Philosophy at the University of Oxford and tutorial fellow of St Hugh's College, Oxford. His main areas of interest are Kant, Wittgenstein, history of philosophy, metaphysics, philosophy of mathematics, philosophy of logic and language, ethics and philosophy of religion.