Epistemology

Hilary Putnam Hilary Whitehall Putnam was one of the most versatile and intellectually honest philosophers of the twentieth century. Over a career spanning six decades, mostly at Harvard, Putnam pursued an unusual philosophical itinerary: he defended positions that he later criticised with the same energy with which he had established them. He was a functionalist and then rejected functionalism; a scientific realist and then proposed “internal realism”; a sympathiser with logical positivism and then its critic. This willingness for self-criticism is one of the hallmarks of his philosophical style. ...

Immanuel Kant Born in Königsberg, in East Prussia, in 1724, and never having strayed from his native city, Immanuel Kant led the methodical life of a university professor — so regular, tradition holds, that his neighbors set their clocks by his daily walk. It was, in his own words, the reading of Hume that “awakened him from his dogmatic slumber” and led him into a long decade of silence, at the end of which, already 57 years old, he published the monumental Critique of Pure Reason (1781). His work both closes and refounds Modernity, mediating the dispute between the rationalism of Descartes and the empiricism of Hume. ...

Imre Lakatos Imre Lakatos was a Hungarian-British philosopher of science and mathematics, a professor at the London School of Economics and one of the central figures in the debate on scientific rationality during the 1960s and 1970s. His work seeks an intermediate position between Popper’s falsificationism and Kuhn’s historical account: against the idea that a single refutation overturns a theory, but also against the idea that scientific change is mere irrational “conversion”. Lakatos proposed that the unit of scientific appraisal is not the isolated theory but the research programme, judged over time by its capacity to anticipate novel facts. He was also an original philosopher of mathematics, showing in Proofs and Refutations that mathematical knowledge grows through a dynamic process of conjectures, proofs, and counterexamples rather than by pure, finished deduction. ...

Joseph Maréchal was a Belgian Jesuit philosopher and psychologist, founder of Transcendental Thomism — a movement that undertook a synthesis between Thomistic metaphysics and Kant’s critical philosophy. His work marks a decisive moment in the renewal of Scholasticism in the 20th century and exerted profound influence on figures such as Karl Rahner and Bernard Lonergan. Key Concepts The Starting Point of Metaphysics (Le Point de départ de la Métaphysique, 5 notebooks, 1922–1947): His principal work. Maréchal traces the history of epistemology — from Greek philosophy through Kantianism — to ground Thomistic metaphysics in the face of Kantian critique. Notebook V (“Thomism Confronting Critical Philosophy”) is the most discussed. ...

Paul Feyerabend Paul Feyerabend was an Austrian philosopher of science and one of the most provocative thinkers of the twentieth century. Trained in Vienna and based for decades at Berkeley, he began close to logical empiricism and to Popper’s critical rationalism — he even studied under Popper at the London School of Economics — before becoming one of his sharpest critics. His best-known work, Against Method (1975), defends epistemological anarchism: the thesis that there is no single, universal, ahistorical scientific method capable of explaining the success of science. Examining real episodes from the history of science, above all the case of Galileo, Feyerabend argues that progress has often required breaking the methodological rules then in force. His provocation became synonymous with a radical defence of pluralism and intellectual freedom against every dogmatism — including the scientific one. ...

Plato Student of Socrates and the most influential philosopher of antiquity, Plato was born into an aristocratic Athenian family around 428 BCE. His master’s execution in 399 BCE marked him deeply and turned him away from the political career his lineage had reserved for him. After years of travel — which tradition links to contact with the Pythagoreans of southern Italy and to his failed attempts to educate the tyrants of Syracuse — he founded the Academy around 387 BCE, the first institution of higher learning in the West, which would endure for more than nine centuries. His work has reached us almost intact, almost entirely in the form of dialogues, with Socrates as the central character. ...

René Descartes Often called the “father of modern philosophy,” René Descartes was born in 1596 in La Haye, in the French region of Touraine, and was educated at the rigorous Jesuit college of La Flèche. Dissatisfied with bookish learning, he enlisted as a volunteer in the armies of the Thirty Years’ War; it was during this period, by his own account, that in 1619 he glimpsed a universal method capable of giving philosophy the same certainty as mathematics. He spent most of his productive life in the Dutch Republic and died in 1650 in Stockholm, where he had been invited to tutor Queen Christina of Sweden. He was also a great mathematician: analytic geometry and the coordinate system that bears his name are his creations. ...

Richard Rorty Richard McKay Rorty was an American philosopher who taught at Princeton, the University of Virginia, and Stanford. He began as an analytic philosopher formed in the Wittgenstein-Sellars tradition, but Philosophy and the Mirror of Nature (1979) projected him as one of the most radical critics of the Western epistemological tradition. Rorty is the principal representative of neopragmatism, which combines the American pragmatist heritage (Dewey, James) with elements of continental philosophy (Heidegger, Derrida) and late analytic philosophy (Wittgenstein, Quine, Sellars). ...

Sextus Empiricus Greek physician and philosopher, the principal systematizer of Pyrrhonian skepticism. His works are the most complete source on the ancient skeptical tradition founded by Pyrrho. While the dogmatists (Stoics, Epicureans, Platonists) claimed to reach definitive truth, Sextus defends the suspension of judgment (epoché) as the path to tranquility (ataraxia). His influence was decisive on modern philosophy, especially on Montaigne, Descartes, and Hume. Sextus Empiricus probably lived and wrote between the second and third centuries CE, at a time when Pyrrhonian skepticism had been revived by Aenesidemus roughly two centuries after Pyrrho of Elis. The epithet “Empiricus” signals his affiliation with the Empiric school of medicine, which rejected hidden causal theories and confined itself to observable experience — a methodological stance that directly mirrors his philosophy. Although almost nothing is known of his biography, his textual output is exceptional: the Outlines of Pyrrhonism offers a pedagogical presentation of the skeptical method in three books, while the eleven books of Adversus Mathematicos systematically dismantle the knowledge-claims of grammarians, rhetoricians, geometers, arithmeticians, astrologers, musicians, logicians, natural philosophers, and ethicists. This breadth shows that Sextus’s skepticism was not intellectual nihilism, but a rigorous philosophical program: by demonstrating that for every dogmatic assertion there is a counter-argument of equal force (isostheneia), he aims to induce suspension of judgment and, as a consequence, peace of mind. ...

W.V.O. Quine Willard Van Orman Quine was one of the most influential analytic philosophers of the 20th century. A professor at Harvard for decades, his work revolutionised epistemology, philosophy of language, and ontology, while simultaneously dismantling the foundations of the logical positivism of the Vienna Circle. Quine is the principal link between American pragmatism (Dewey, James) and contemporary analytic philosophy. Key Concepts Critique of the Analytic/Synthetic Distinction (“Two Dogmas of Empiricism”, 1951, Philosophical Review; reprinted in From a Logical Point of View, 1953): Quine attacks two dogmas of empiricism: (1) the belief in a sharp distinction between analytic propositions (true by meaning, e.g. “all bachelors are unmarried”) and synthetic ones (true by empirical fact); and (2) reductionism (each statement has an isolated empirical content). Quine argues that the notion of “analyticity” is circular — it presupposes “synonymy”, which presupposes “analyticity”. ...

Wilfrid Sellars Wilfrid Sellars was one of the most profound and original American analytic philosophers of the twentieth century, though less widely read than his influence would warrant. Trained in a tradition that combined analytic rigor with a deep knowledge of the history of philosophy, he set out to articulate what he called the ultimate aim of philosophy: “to understand how things in the broadest possible sense of the term hang together in the broadest possible sense of the term.” His work seeks to reconcile a commitment to science and naturalism with recognition of the normative dimension of thought and knowledge. He taught above all at the University of Pittsburgh, where he formed an influential line of students. ...

Wilhelm Dilthey Wilhelm Dilthey was born in Biebrich am Rhein (present-day Wiesbaden, Germany) on 19 November 1833 and died in Seis am Schlern (present-day northern Italy) on 1 October 1911. He held professorships in Basel, Kiel, and from 1882 in Berlin — where he occupied the chair once held by Hegel — and devoted his life to a project that remained unfinished yet profoundly influential: providing the human sciences (Geisteswissenschaften) with their own philosophical foundation, comparable to what Kant had given the natural sciences in the Critique of Pure Reason. ...