German philosophy, here taken to mean either (1) philosophy in the German language or (2) philosophy by Germans, has been extremely diverse, and central to both the analytic and continental traditions in philosophy for centuries, from Leibniz through Kant, Hegel, Schopenhauer, Marx, Nietzsche, Heidegger and Wittgenstein to contemporary philosophers. Søren Kierkegaard (a Danish philosopher) is frequently included in surveys of German (or Germanic) philosophy due to his extensive engagement with German thinkers.

Gottfried Wilhelm Leibniz (1646–1716) was both a philosopher and a mathematician who wrote primarily in Latin and French. Leibniz, along with René Descartes and Baruch Spinoza, was one of the three great 17th century advocates of rationalism. The work of Leibniz also anticipated modern logic and analytic philosophy, but his philosophy also looks back to the scholastic tradition, in which conclusions are produced by applying reason to first principles or a priori definitions rather than to empirical evidence.

Immanuel Kant (German pronunciation: [ɪˈmaːnu̯eːl ˈkant]; 22 April 1724 – 12 February 1804) was a German philosopher from Königsberg (today Kaliningrad of Russia), who researched, lectured, and wrote on philosophy and anthropology during the Enlightenment at the end of the 18th century. At the time, there were major successes and advances in the sciences (for example, Isaac Newton, Carl Friedrich Gauss, and Robert Boyle) applying reason and logic.

Kant’s major work, the Critique of Pure Reason (Kritik der reinen Vernunft, 1781), aimed to unite reason with experience to move beyond what he took to be failures of traditional philosophy and metaphysics. He hoped to end an age of speculation where objects outside experience were used to support what he saw as futile theories, while opposing the skepticism of thinkers such as Descartes, Berkeley and Hume.

He stated:

Kant proposed a ‘Copernican Revolution’ in reverse, saying that:

Kant published other important works on ethics, religion, law, aesthetics, astronomy, and history. These included the Critique of Practical Reason (Kritik der praktischen Vernunft, 1788) and the Metaphysics of Morals (Die Metaphysik der Sitten, 1797), which dealt with ethics. And the Critique of Judgment (Kritik der Urteilskraft, 1790), which looks at aesthetics and teleology. He aimed to resolve disputes between empirical and rationalist approaches. The former asserted that all knowledge comes through experience; the latter maintained that reason and innate ideas were prior. Kant argued that experience is purely subjective without first being processed by pure reason. He also said that using reason without applying it to experience only leads to theoretical illusions. The free and proper exercise of reason by the individual was both a theme of the Enlightenment, and of Kant's approaches to the various problems of philosophy.

William James Durant (November 5, 1885 – November 7, 1981) was a prolific American writer, historian, and philosopher. He is best known for The Story of Civilization, 11 volumes written in collaboration with his wife Ariel Durant and published between 1935 and 1975. He was earlier noted for The Story of Philosophy, written in 1926, which one observer described as "a groundbreaking work that helped to popularize philosophy."

He conceived of philosophy as total perspective, or, seeing things "sub specie totius," a phrase inspired by Spinoza's "sub specie aeternitatis." He sought to unify and humanize the great body of historical knowledge, which had grown too voluminous and become fragmented into esoteric specialties, and to vitalize it for contemporary application. Durant was a gifted prose stylist and storyteller who won a large readership in great part because of the nature and excellence of his writing, which, in contrast to formal academic language, is lively, witty, charismatic, colourful, ornate, epigrammatic, in short, "humanized." Max Schuster, co-founder of the publisher Simon & Schuster (which also published Durant's works), and himself an admirer of Durant's writings for their beauty, remarked that Durant's prose "begs to be read aloud."John Little, who founded and heads the Will Durant foundation and has devoted much effort towards popularizing Durant's works in the 21st century, echoes Schuster's admiration for Durant's works in words which Durant himself sometimes used to describe a few of the finest works of Classical Antiquity: "prose so beautiful it rivals poetry."

Friedrich Wilhelm Nietzsche ( /ˈniːtʃə/;German pronunciation: [ˈfʁiːdʁɪç ˈvɪlhɛlm ˈniːtsʃə]; October 15, 1844 – August 25, 1900) was a German philosopher, poet, cultural critic and classical philologist. He wrote critical texts on religion, morality, contemporary culture, philosophy and science, displaying a fondness for metaphor, irony and aphorism.

Nietzsche's influence remains substantial within and beyond philosophy, notably in existentialism, nihilism and postmodernism. His style and radical questioning of the value and objectivity of truth have resulted in much commentary and interpretation, mostly in the continental tradition. His key ideas include the death of God, the Übermensch, the eternal recurrence, the Apollonian and Dionysian dichotomy, perspectivism and the will to power. Central to his philosophy is the idea of "life-affirmation", which involves an honest questioning of all doctrines that drain life's expansive energies, however socially prevalent and radical those views might be.

Arthur Schopenhauer (22 February 1788 – 21 September 1860) was a German philosopher known for his pessimism and philosophical clarity. At age 25, he published his doctoral dissertation, On the Fourfold Root of the Principle of Sufficient Reason, which examined the four separate manifestations of reason in the phenomenal world.

Schopenhauer's most influential work, The World as Will and Representation, claimed that the world is fundamentally what humans recognize in themselves as their will. His analysis of will led him to the conclusion that emotional, physical, and sexual desires can never be fully satisfied. The corollary of this is an ultimately painful human condition. Consequently, he considered that a lifestyle of negating desires, similar to the ascetic teachings of Vedanta, Buddhism and the Church Fathers of early Christianity, was the only way to attain liberation.

Schopenhauer's metaphysical analysis of will, his views on human motivation and desire, and his aphoristic writing style influenced many well-known thinkers, including Friedrich Nietzsche,Richard Wagner, Ludwig Wittgenstein, Erwin Schrödinger, Albert Einstein,Sigmund Freud, Otto Rank, Carl Jung, Joseph Campbell, Leo Tolstoy, Thomas Mann, and Jorge Luis Borges.