History and Sources of Critical Thinking
Many streams feed the river
Les petits ruisseaux font les grandes rivières.
The word "critical" goes back to the Greek krínein: to distinguish, to separate, to judge. As an educational ideal, however, "critical thinking" is quite young. John Dewey used the expression in 1910 in How We Think as the name for an educational goal.1 The practices of thought behind it are much older: asking questions, testing claims, demanding reasons, uncovering contradictions, questioning authorities, telling the appearance of knowledge from the real thing, recognising one's own prejudices and revising one's judgements.
These practices have no single origin and no straight line of descent. Like a river fed by many streams, critical thinking draws on many traditions: on Greek and European philosophy just as much as on Chinese, Indian, Islamic-Arabic, African and Latin American sources. The pioneers on this page pursued very different aims. Some sought religious truth, others scientific knowledge, political freedom or a life well lived. Every one of them, however, contributed a building block that today belongs to the toolkit of critical thinking.
Two overviews first show how these building blocks fit together: "The common thread" reads the history as a sequence of questions, "Different aspects of critical thinking" arranges the people by their particular focus. The portraits then follow in chronological order, each with the most important works and the building block that the person left behind.
The common thread
If you read the portraits not as a list but as a story of development, something interesting emerges:
| Phase | Central question |
|---|---|
| Socrates | "Why do you believe that?" |
| Aristotle | "Is the inference logically valid?" |
| Nāgārjuna / Sextus | "What reasons speak for the opposing position as well?" |
| Ibn al-Haytham | "Can we test it empirically?" |
| Ibn Khaldūn | "Is this source plausible in the first place?" |
| Montaigne / Bacon | "Which prejudices are distorting my judgement?" |
| Descartes / Hume | "How certain can I actually be?" |
| Spinoza / Kant | "Why should I believe an authority?" |
| Wollstonecraft / Mill | "Which social convictions are never examined?" |
| Dewey | "How can critical thinking be learned?" |
| Arendt | "How can we judge for ourselves under social pressure?" |
| Freire | "How can critical thinking enable people to change their world?" |
| Foucault | "Who decides what counts as true?" |
| Kahneman / Tversky | "Which errors of reasoning do we make systematically?" |
| Sagan | "How do I recognise nonsense?" |
| Sokal / Bricmont | "Do the critics themselves live up to their own standards?" |
| Paul / Elder, Facione | "By which standards do I examine my own thinking?" |
| Baillargeon / Bronner | "How do I defend myself against manipulation and disinformation?" |
Different Aspects of Critical Thinking
These thinkers have shaped critical thinking in a variety of ways:
- Logic & method: Aristotle, Descartes, Spinoza (systematising arguments).
- Scepticism & questioning: Socrates, Sextus Empiricus, Voltaire, Sokal and Bricmont (questioning authorities and dogmas).
- Ethical reflection: Confucius, the Buddha, Kant (self-examination and moral autonomy).
- Socio-political critique: Wollstonecraft, Fanon, Arendt (critique of oppression, colonialism, totalitarianism).
- Science & empiricism: Ibn Rushd, Locke, Hypatia, Sagan (emphasis on experience and evidence).
- Psychology of thinking: Kahneman and Tversky, Bronner (systematic errors of reasoning and how convictions spread).
Pioneers
Antiquity
Confucius (China, c. 551–479 BCE)
Learning and thinking belong together. Received knowledge should not simply be memorised but understood and worked through with one's own power of judgement. For Confucius, learning without reflection is just as inadequate as reflection without learning. That makes him an early advocate of a reflective education.2
Work: Lunyu (Analects)
Building block: Learning and self-examination.
The Buddha (India, c. 5th–4th century BCE)
In the Kālāma Sutta the Buddha advises against believing anything merely because of tradition, hearsay, authority or sacred scriptures, and recommends examining for oneself what leads to benefit or to harm. This is one of the earliest explicit calls to test things for oneself instead of believing authorities.
Work: no writings of his own; transmitted in the Pali Canon, especially in the Kālāma Sutta
Building block: Testing for oneself instead of believing authority.
Socrates (Greece, c. 469–399 BCE)
With Socrates one of the most important lines of all begins. He proclaims no doctrine but asks questions. With the elenchus he tests claims: he has his interlocutors state their reasons and shows where their statements contradict one another.
His central contribution to critical thinking is an attitude: "What exactly do you mean? How do you know that? Does that fit with what you claim elsewhere?" Part of it is intellectual humility, which has become proverbial as "I know that I know nothing". This method lives on to this day in "Socratic questioning".3
Works: no writings of his own; transmitted above all through Plato's Apology, Euthyphro, Laches, Gorgias
Building block: Asking questions, clarifying concepts, discovering contradictions.
Mozi (China, c. 5th century BCE)
Mozi and the Mohists are surprisingly little known in the West. Yet in China they developed an explicit culture of argumentation very early on. They looked for intelligible criteria for right action and developed step-by-step arguments, techniques of discussion and early forms of argument from analogy. Moral and political questions were to be settled through discussion and reasoned inquiry.4
Work: Mozi
Building block: Arguments instead of mere authority.
Aristotle (Greece, 384–322 BCE)
With Aristotle, the art of argumentation becomes a systematic theory of inference. He founded formal logic (syllogistic) and distinguished valid from invalid inferences. In the Sophistical Refutations he analysed fallacies and seemingly good arguments.5 In doing so he supplied the tools that to this day form the core of every training in critical thinking: analysing arguments and recognising fallacies.
Works: the writings of the Organon, especially Analytica priora (Prior Analytics), Analytica posteriora (Posterior Analytics), Topics, Sophistical Refutations
Building block: The logical structure of arguments.
Wang Chong (China, 27–c. 100 CE)
In his Lunheng, Wang Chong systematically refutes superstition, miracle stories and mere appeals to authority, using arguments drawn from experience. Instead of invoking the ancients, he demands evidence. He shows that naturalistic scepticism and the critique of superstition are not a European invention.
Work: Lunheng ("Critical Discussions")
Building block: Evidence instead of appeals to the ancients.
Nāgārjuna (India, c. 150–250)
Nāgārjuna is a particularly fascinating ancestor from Indian philosophy. He investigates how apparently self-evident concepts can deceive us. In the Mūlamadhyamakakārikā he pushes arguments so far that supposedly fixed categories and oppositions lose their obviousness.
In the process, the Madhyamaka tradition develops a radical critique of the assumption that things possess an independent, unchanging nature of their own.6
Work: Mūlamadhyamakakārikā (Fundamental Verses on the Middle Way)
Building block: Examining concepts themselves critically.
Sextus Empiricus (Roman Empire, c. 2nd–3rd century CE)
Sextus is one of the great ancestors of methodical scepticism. He collects arguments for and against a position. If both sides appear equally convincing, judgement should be suspended for the time being (epoché).
For critical thinking it is precisely this ability that matters: not judging too quickly. Scepticism here does not mean holding everything to be false, but keeping one's own certainty in check.7
Work: Outlines of Pyrrhonism
Building block: Doubt, counterarguments, suspension of judgement.
Hypatia of Alexandria (Egypt, c. 360–415)
Hypatia taught mathematics, astronomy and philosophy and defended rational thought at a time of fierce religious conflict. In 415 she was murdered by a Christian mob. Ever since, she has been a symbol of free scholarship and of resistance to intolerance.
Work: no surviving writings; known through historical accounts
Building block: Reason and science against dogmatism.
The Middle Ages
Al-Fārābī (Central Asia/Baghdad, c. 872–950)
Al-Fārābī combined Greek logic and philosophy (Aristotle, Plato) with Islamic theology. For him, reason was a tool for interpreting revelation as well. As a major commentator on Aristotle he was given the byname "the second teacher".
Works: The Perfect State (Ārāʾ ahl al-madīna al-fāḍila), commentaries on Aristotle
Building block: Reason as the standard of interpretation.
Ibn al-Haytham / Alhazen (Basra/Cairo, c. 965–1040)
With Ibn al-Haytham another important line is added: critical thinking as empirical investigation. In his Book of Optics he combines methodical doubt with observation, mathematical models and targeted experiments. What is decisive here is the experimental testing of a hypothesis.8 Whoever seeks the truth, says Ibn al-Haytham, must critically examine the recognised authorities as well.
This makes him a pioneer of the scientific method long before Bacon:
Not: "Aristotle said so."
but rather:
"What observation or what experiment would show that it is true?"
Works: Book of Optics (Kitāb al-Manāẓir), Doubts Concerning Ptolemy (al-Shukūk ʿalā Baṭlamyūs)
Building block: Hypothesis → test → evidence.
Peter Abelard (France, 1079–1142)
In Sic et Non, Abelard places contradictory statements by ecclesiastical authorities side by side and thereby forces the reader into careful weighing: "By doubting we come to inquiry, and by inquiry we perceive the truth." In this way he made methodical doubt a foundation of the scholastic method.
Work: Sic et Non
Building block: Exposing and weighing contradictions between authorities.
Ibn Rushd / Averroes (Al-Andalus, 1126–1198)
Ibn Rushd is a key figure between Greek, Islamic, Jewish and later European philosophy. He defended the possibility of rational knowledge and worked intensively on Aristotle. At the same time he distinguished different forms of argumentation: strict demonstration, dialectic and rhetoric.9
In the Decisive Treatise he sets out why philosophical reflection is compatible with faith and even required; in the Incoherence of the Incoherence he defends philosophy against al-Ghazālī's attack. Through Latin translations, "Averroism" shaped the debates of the medieval universities. A fine case of a bridge: geographically Europe, culturally Arabic-Islamic.
Works: Decisive Treatise (Faṣl al-maqāl), The Incoherence of the Incoherence (Tahāfut al-tahāfut), commentaries on Aristotle
Building block: Reason as an independent authority of examination.
William of Ockham (England, c. 1287–1347)
"Ockham's razor": of competing explanations, the most economical is to be preferred; superfluous assumptions are to be struck out. To this day the principle is a central tool for critically assessing theories and claims.
Work: Summa Logicae
Building block: Economy of explanation.
Ibn Khaldūn (Tunis/North Africa, 1332–1406)
In the Muqaddima, Ibn Khaldūn asks how historical reports can be tested for whether they are plausible in the first place. Transmitted stories should not simply be taken over; they have to be checked against social structures, economic conditions and human behaviour. His declared aim is to distinguish, through critical investigation, between true and false historical reports.10
In doing so he looks for the causes of social and economic processes, for instance with the concept of ʿasabiyya, group cohesion. He is therefore regarded as a pioneer of a source-critical history and social science.
Work: Muqaddima
Building block: Source criticism and plausibility checking.
Christine de Pizan (France, 1364–c. 1430)
Christine de Pizan was one of the first women to call for education and critical thinking for women. In The City of Ladies she contradicts the misogynistic verdicts of learned authorities and questions the social role models of her time.
Work: Le Livre de la Cité des Dames (The Book of the City of Ladies)
Building block: Questioning role models and the authorities behind them.
The Early Modern Period
Michel de Montaigne (France, 1533–1592)
Montaigne makes his own judgement itself the object of investigation. In the Essais he examines not only the world but also himself: Why do I believe this? Where does my conviction come from? How far does my judgement depend on habit, culture or upbringing?
The Essais are therefore a kind of laboratory of personal judgement.11
Work: Essais
Building block: Self-reflection and intellectual humility.
Francis Bacon (England, 1561–1626)
Bacon directs his critique straight at the sources of error in our thinking. In the Novum Organum he describes the famous "idols": systematic distortions that arise from human nature, from language, from the individual perspective or from inherited pictures of the world. He thus named cognitive biases centuries before psychology did.
Knowledge should therefore rest on observation, experiment and induction, and not on systems of thought taken over uncritically.12
Work: Novum Organum
Building block: Recognising bias and controlling it empirically.
René Descartes (France, 1596–1650)
Descartes turns doubt into a method. In the Meditations and in the Discours de la méthode he asks: What can I really accept as certain? He systematically examines his convictions for possible grounds of doubt and rejects everything that can be doubted, until he arrives at the unshakeable "I think, therefore I am" (cogito ergo sum).
In doing so he formulates methodical rules: accept nothing as true that is not clear and tested; break problems down; begin with what is simple; proceed step by step.13
Works: Discours de la méthode, Meditationes de prima philosophia
Building block: Systematic doubt and methodical procedure.
Zera Yacob (Ethiopia, 1599–1692)
In the Hatäta, Zera Yacob examines the competing religions by the "light of reason" and rejects whatever contradicts reason and the equality of human beings. He is thus an independent African voice of the Enlightenment, almost contemporary with Descartes.
The authenticity of the text is, however, disputed among specialists: a good occasion to practise critical thinking on this very example.
Work: Hatäta ("Inquiry")
Building block: Testing religious tradition against the standard of reason.
John Locke (England, 1632–1704)
Locke is regarded as the founder of modern empiricism: knowledge comes from experience. His political writings demand that authority justify itself, and his letter on toleration argues for religious tolerance.
Works: An Essay Concerning Human Understanding, Two Treatises of Government, A Letter Concerning Toleration
Building block: Experience as the touchstone; authority must justify itself.
Baruch de Spinoza (the Netherlands, 1632–1677)
Spinoza brings critical thinking to the field of religion, biblical interpretation and political freedom. In the Theological-Political Treatise he reads the Bible in a historical-critical way instead of treating its statements as philosophical or scientific truths, and he separates faith from testable knowledge.
At the same time he defends the freedom to philosophise, that is, freedom of thought and of speech.14 He is thus an early pioneer of the critique of texts and of ideology.
Work: Tractatus theologico-politicus (Theological-Political Treatise)
Building block: Critique of authority and free inquiry.
The Enlightenment
Voltaire (France, 1694–1778)
For Voltaire, enlightenment is critique. With mockery and satire he denounced religious fanaticism, absolutism and social injustice, and campaigned for freedom of opinion and for tolerance.
Works: Candide ou l'Optimisme, Traité sur la tolérance (Treatise on Tolerance)
Building block: Satire as a weapon against fanaticism.
David Hume (Scotland, 1711–1776)
Hume raises an uncomfortable question: how certain are our inferences from experience in the first place? His analysis of cause and effect leads to the famous problem of induction: we observe only regularities, no necessary connection. Just because something has always happened so far, it does not follow logically that it will happen tomorrow as well.15
To this are added his critique of reports of miracles ("A wise man proportions his belief to the evidence") and the distinction between is and ought. Hume thus becomes the grandfather of modern epistemic humility: many of our convictions rest on habit and probability, not on certainty.
Works: A Treatise of Human Nature, An Enquiry Concerning Human Understanding
Building block: Evidence ≠ certainty.
Immanuel Kant (Prussia, 1724–1804)
With Kant, critical thinking takes on a new meaning: enlightenment means thinking for yourself. In Beantwortung der Frage: Was ist Aufklärung? (An Answer to the Question: What Is Enlightenment?) he demands: Sapere aude! "Have the courage to use your own understanding!" Particularly important is his idea of the public use of reason: thinking must justify itself publicly and be able to withstand criticism.16
In his three Critiques, reason examines its own limits and conditions. In this way Kant gave the word "critique" its modern meaning: examining the conditions of one's own knowing.
Works: Beantwortung der Frage: Was ist Aufklärung? (An Answer to the Question: What Is Enlightenment?), Kritik der reinen Vernunft (Critique of Pure Reason), Kritik der praktischen Vernunft (Critique of Practical Reason), Kritik der Urteilskraft (Critique of the Power of Judgement)
Building block: Autonomy of judgement + public examination.
Mary Wollstonecraft (England, 1759–1797)
Wollstonecraft asks the critical question: are social differences really natural, or are they produced by education? In A Vindication of the Rights of Woman she argues that women are not by nature less rational. Their alleged inferiority, she says, is a product of upbringing, social position and the interests of others.17
In this way she applies critical thinking to what a society takes for granted and to its relations of power, and turns the Enlightenment against its own blind spots.
Work: A Vindication of the Rights of Woman
Building block: Making social norms themselves an object of examination.
The 19th Century
John Stuart Mill (England, 1806–1873)
Mill turns the free contest of opinions into an instrument of knowledge. In On Liberty he argues that a society should not suppress opinions even when they are false or uncomfortable. A suppressed opinion might be true, or it might contain a part of the truth. And even when it is false, it forces the majority to examine their own reasons instead of cultivating their convictions as dead dogmas.
Free discussion thereby becomes not merely a political right, but a method of gaining knowledge.18
Work: On Liberty
Building block: Dissent as a source of knowledge.
Karl Marx (Germany, 1818–1883)
Marx practises the critique of ideology: he reads apparent self-evidences as expressions of interests and power relations. Asking which interests and forms of domination lie behind a statement has been a basic move of every critique of ideology and power ever since.
Works: Die deutsche Ideologie (The German Ideology, with Friedrich Engels), Zur Kritik der politischen Ökonomie (A Contribution to the Critique of Political Economy), Das Kapital (Capital)
Building block: Asking about the interests behind ideas.
Friedrich Nietzsche (Germany, 1844–1900)
Nietzsche does not take values as given but asks about their origin and their function. He pushes questioning all the way to values themselves; Götzen-Dämmerung (Twilight of the Idols) carries the subtitle “How to Philosophise with a Hammer”. Paul Ricœur counted him, together with Marx and Freud, among the three “masters of suspicion” (De l'interprétation. Essai sur Freud, 1965).
Works: Zur Genealogie der Moral (On the Genealogy of Morality), Götzen-Dämmerung (Twilight of the Idols)
Building block: Asking about the origin and function of values.
The 20th Century
John Dewey (USA, 1859–1952)
Here we come to the actual grandfather of modern critical thinking in education. In How We Think (1910), Dewey describes “reflective thinking” as the active, persistent and careful examination of a belief in the light of the grounds that support it and the consequences to which it leads.
The modern discussion of critical thinking in education connects directly to this tradition.1
Work: How We Think
Building block: Critical thinking as a learnable thinking skill.
Rabindranath Tagore (India, 1861–1941)
Tagore was a poet and a philosopher. He defended cultural diversity and human solidarity against dogmas and divisions, and criticised colonialism as much as nationalism. His writings call for creative and free thinking.
Works: Gitanjali (collection of poems), Nationalism, The Religion of Man
Building block: Free thinking against nationalist narrowing.
The Frankfurt School (Germany/USA, from the 1930s onwards)
Max Horkheimer (1895–1973) coined the term “critical theory” in 1937. In Dialektik der Aufklärung (Dialectic of Enlightenment) he and Theodor W. Adorno (1903–1969) show that reason and progress can themselves turn into domination; they criticise instrumental reason and the “culture industry”. In doing so, they gave the word “critical” its socially critical, emancipatory meaning: thinking that aims at change.
Works: Horkheimer: Traditionelle und kritische Theorie (Traditional and Critical Theory); Horkheimer/Adorno: Dialektik der Aufklärung (Dialectic of Enlightenment)
Building block: Interrogating reason itself for domination.
Karl Popper (Vienna/London, 1902–1994)
Popper founded critical rationalism. According to his principle of falsification, what is scientific is what can be refuted; knowledge grows through conjectures and refutations. He thereby made criticism the engine of the growth of knowledge: what counts is not confirmation, but the honest search for refutation. In Die offene Gesellschaft und ihre Feinde (The Open Society and Its Enemies) he carries this attitude over into politics.
Works: Logik der Forschung (The Logic of Scientific Discovery), Die offene Gesellschaft und ihre Feinde (The Open Society and Its Enemies), Vermutungen und Widerlegungen (Conjectures and Refutations)
Building block: Looking for refutation, not confirmation.
Hannah Arendt (Germany/USA, 1906–1975)
Arendt adds an important dimension: one can know without really thinking. In The Life of the Mind and in her work on judgement she examines the relationship between thinking, self-examination and moral judgement. Thinking should loosen the taken-for-granted categories that govern our judgement.
Particularly important is her idea of judging from different perspectives: we have to try not to think exclusively from our own standpoint.19
Works: Eichmann in Jerusalem, The Life of the Mind
Building block: Thinking against conformism and “thoughtlessness”.
Paulo Freire (Brazil, 1921–1997)
Freire carries critical thinking over into education and social emancipation. In Pedagogia do Oprimido (Pedagogy of the Oppressed) he criticises the traditional model in which teachers pour knowledge “into” passive learners. Learning should instead be dialogical and enable people to investigate their own social reality for themselves.
His concept of conscientização, critical consciousness-raising, links learning, reflection and the ability to understand one's own social situation.20
Work: Pedagogia do Oprimido (Pedagogy of the Oppressed)
Building block: Critical thinking as a dialogical and emancipatory educational process.
Frantz Fanon (Martinique/Algeria, 1925–1961)
As early as Peau noire, masques blancs (Black Skin, White Masks), Fanon examines how racism shapes the self-image of the colonised. In Les Damnés de la Terre (The Wretched of the Earth) he analyses the psychological and political consequences of colonialism and calls for liberation through the raising of consciousness. His writings are among the foundations of postcolonial theory and of critical research on racism.
Works: Peau noire, masques blancs (Black Skin, White Masks), Les Damnés de la Terre (The Wretched of the Earth)
Building block: Uncovering colonial patterns of thought.
Michel Foucault (France, 1926–1984)
Foucault asks how knowledge and power are connected: who determines what counts as true, normal or rational in a given epoch? In his historical studies of madness, the prison and sexuality he shows that apparently neutral categories emerge from discourses and institutions, and that they order, classify and control people.
In his lecture “What Is Critique?” (1978) he defines critique as “the art of not being governed quite so much”. In doing so he explicitly takes up Kant's question about enlightenment.
Works: Les Mots et les choses (The Order of Things), Surveiller et punir (Discipline and Punish), Qu'est-ce que la critique? (What Is Critique?)
Building block: Asking who determines what counts as true.
Daniel Kahneman and Amos Tversky (Israel/USA, 1934–2024 and 1937–1996)
In their experiments, the two psychologists showed that people judge wrongly not at random, but systematically. Under uncertainty we fall back on rules of thumb (heuristics), for instance on whatever happens to come to mind easily, or on a randomly mentioned number that serves as an anchor. These rules of thumb are usually useful, but they lead to predictable cognitive biases.
What Bacon had described philosophically with his “idols” thus became the object of empirical research. Kahneman received the Nobel Prize in Economics for this work in 2002; Tversky had already died. In Thinking, Fast and Slow Kahneman sums up the research with the image of two systems of thinking: one fast and intuitive, the other slow and examining.
Works: Tversky/Kahneman: Judgment under Uncertainty: Heuristics and Biases (1974); Kahneman: Thinking, Fast and Slow (2011)
Building block: Knowing your own thinking errors, because they are predictable.
Carl Sagan (USA, 1934–1996)
The astronomer and science communicator brought sceptical thinking to a broad audience. In The Demon-Haunted World he presents his “baloney detection kit”, a toolbox against nonsense: look for independent confirmation of the facts, examine several hypotheses, distrust arguments from authority, ask whether a claim is refutable at all.
His sentence “Extraordinary claims require extraordinary evidence” became famous. It takes up Hume's principle of proportioning belief to the evidence.
Works: Cosmos (book and television series, 1980), The Demon-Haunted World (1995)
Building block: Scientific scepticism as a tool for everyday life.
Alan Sokal and Jean Bricmont (USA/Belgium, b. 1955 and 1952)
The two physicists turn critical thinking on the critics themselves. In 1996 Sokal submitted to the cultural journal Social Text an essay on a supposedly “transformative hermeneutics of quantum gravity”. The text was a deliberately nonsensical parody of postmodern jargon. The journal printed it anyway, without consulting any experts in physics. It sounded learned and it confirmed the editors' convictions. Shortly afterwards, Sokal made the hoax public.
In Impostures intellectuelles Sokal and Bricmont then document how well-known thinkers such as Jacques Lacan, Julia Kristeva, Jean Baudrillard or Gilles Deleuze and Félix Guattari use terms from mathematics and physics, often without understanding them, and how much of this aims at mere effect. At the same time they criticise an epistemological relativism for which there are no longer any facts, but only interpretations.21
The lesson reaches beyond postmodernism: even those who see themselves as enlighteners and “philosophise with a hammer” can fall prey to deference to authority, impressive-sounding jargon and self-confirmation. Critical thinking that does not examine itself turns into a pose.
Works: Sokal: Transgressing the Boundaries: Towards a Transformative Hermeneutics of Quantum Gravity (1996); Sokal/Bricmont: Impostures intellectuelles (1997; Eng. Fashionable Nonsense, 1998; Ger. Eleganter Unsinn, 1999)
Building block: Examining the critics critically as well.
The Present: Critical Thinking as a Field of Research and Education
Since the 1980s, critical thinking has itself become an object of research. Philosophers and educational researchers argue about how to define it, how to teach it and how to measure it.22 Others carry the tools out to the general public, as a form of self-defence against manipulation and disinformation.
Robert Ennis (USA, b. 1928)
Ennis supplied one of the most frequently quoted definitions: critical thinking is “reasonable, reflective thinking that is focused on deciding what to believe or do”. He distinguishes abilities (such as analysing arguments or judging sources) from dispositions (such as the inclination to look for reasons and alternatives), and he developed tests to measure both.
Works: A Taxonomy of Critical Thinking Dispositions and Abilities (1987), Critical Thinking (1996)
Building block: Defining critical thinking and making it measurable.
Richard Paul and Linda Elder (USA)
With the Foundation for Critical Thinking, Richard Paul (1937–2015) and Linda Elder developed one of the most widely used models for teaching. It breaks thinking down into elements (purpose, question, information, inferences, concepts, assumptions, implications, point of view) and tests them against intellectual standards such as clarity, accuracy, relevance, depth, logic and fairness. To these are added intellectual virtues such as humility, courage and fairness in thinking.
Works: Critical Thinking: Tools for Taking Charge of Your Learning and Your Life; The Miniature Guide to Critical Thinking: Concepts and Tools
Building block: Testing thinking against clear standards.
Peter Facione (USA)
Facione directed the so-called Delphi Report (1990), in which 46 experts agreed on a shared description of critical thinking. On that account it comprises abilities such as interpretation, analysis, evaluation, inference, explanation and self-regulation, carried by attitudes such as inquisitiveness, open-mindedness and a readiness to form judgements. In his essay Critical Thinking: What It Is and Why It Counts (updated in 2015) he makes these results generally accessible.
Works: Critical Thinking: A Statement of Expert Consensus (Delphi Report, 1990), Critical Thinking: What It Is and Why It Counts (2015)
Building block: A shared understanding of critical thinking.
Harvey Siegel (USA, b. 1952)
Siegel emphasises that critical thinking is more than a collection of techniques. A critical thinker is someone who is appropriately moved by reasons. This includes a “critical spirit”: the willingness actually to look for reasons and to take them seriously, even when they speak against one's own opinion. For Siegel, critical thinking is therefore a fundamental ideal of education.
Work: Educating Reason: Rationality, Critical Thinking, and Education (1988)
Building block: Critical thinking as an attitude and an educational ideal.
Normand Baillargeon (Québec, b. 1958)
With his Petit cours d'autodéfense intellectuelle (A Short Course in Intellectual Self-Defense), the philosopher and educational scientist from Québec has written a classic for a broad audience. He shows how to defend oneself against linguistic tricks, misleading numbers and statistics, bad arguments and media manipulation. Critical thinking here becomes intellectual self-defence (see also the chapter Manipulation and Self-Defence).
Work: Petit cours d'autodéfense intellectuelle (2005)
Building block: Critical thinking as self-defence for everyone.
Gérald Bronner (France, b. 1969)
The sociologist investigates why errors, conspiracy theories and false information spread so effectively. In a digital “marketplace of beliefs” it is often not the best-founded ideas that prevail, but those that most flatter our cognitive inclinations. In 2022 he chaired the French commission “Les Lumières à l'ère numérique” (Enlightenment in the digital age).
Works: La Démocratie des crédules (2013), Apocalypse cognitive (2021); with Elena Pasquinelli: Éduquer à l'esprit critique (2021)
Building block: Understanding how beliefs spread in the digital sphere.
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