Schools of Philosophy: The Main -isms and the Questions They Answer

The main schools of philosophy are families of answers to particular questions. Materialism and idealism answer “what is there?”; empiricism and rationalism answer “where does knowledge come from?”; Stoicism, utilitarianism and existentialism answer “how should I live?”. Learn the question behind an -ism and its rivals come into focus.

Philosophy has hundreds of -isms, and lists of them can feel like a vocabulary test. This guide shows how to read any of them, gives a table of twenty well-known schools with the question each answers, then walks through the philosophical schools of thought about reality, knowledge, how to live, politics and religion, and those of Asia and the Islamic world.

What is a school of philosophy?

A school of philosophy is a group of thinkers who share an answer, and often a method or a founder, and defend it over generations. Some were literal schools: Plato’s Academy, the Stoics who taught at the Painted Stoa in Athens, the debaters of India’s Nyāya school. Others are labels applied afterwards: “the British empiricists” is a historian’s grouping, not a club that Locke, Berkeley and Hume joined.

Many words ending in -ism name positions rather than schools. “Compatibilism” and “nominalism” are answers to single questions, held by people who disagree about almost everything else. That is the clue to reading them all.

How to read an -ism: find the question it answers

The insight behind The Coordinates of Thought, the book from which the site’s 131 question cards come, is simple: an -ism is an answer to a question. Materialism is one answer to What is there? Idealism and dualism are rival answers to the same question. Utilitarianism is one answer to If an act produces the best outcome, can it be wrong? — it says no.

So when you meet an -ism, ask three things. Which question does it answer? What are the rival answers to that question? What is the strongest objection to this one? Each card on The Coordinates is built to answer exactly those three.

Some schools answer several questions at once, which is why they feel like whole ways of life. Stoicism answers Could you have done otherwise? as compatibilists — everything happens by fate, yet assent is your own — and Should ethics ask what to do, or who to be? with virtue as the only good. It also had its own logic and physics. Break a school into its answers and you can accept one without the rest.

Two cautions. The same word can answer different questions: “nihilism” means one thing in ethics and quite another in the metaphysics of parts and wholes (see nihilism vs existentialism). And the same answer can carry different names in different traditions: European nominalism has a Buddhist relative in Dignāga’s apoha theory.

A list of philosophies: 20 -isms and the questions they answer

-ism	The question it answers	The answer in a line	Key figures
Materialism	What is there?	Only physical things exist; minds are physical processes	Democritus, Lucretius, Ajita Kesakambali
Idealism	What is there?	Only minds and their contents exist, or the mental comes first	George Berkeley; Vasubandhu, on a common reading
Dualism	How can a thought move an arm?	Mind and body are two distinct substances	René Descartes
Platonism	A tomato and a fire engine are both red. Is there something they share?	Yes: universals exist in their own right, outside space and time	Plato
Nominalism	A tomato and a fire engine are both red. Is there something they share?	No: only particulars exist; the sharing lies in our words or concepts	William of Ockham; Dignāga (apoha)
Compatibilism	Could you have done otherwise?	Free will and determinism can both be true	Chrysippus, David Hume
Rationalism	Which ways of finding things out actually work?	Reason gives some substantive knowledge independently of experience	René Descartes, Baruch Spinoza, G. W. Leibniz
Empiricism	Which ways of finding things out actually work?	Experience comes first; reason arranges what it supplies	John Locke, George Berkeley, David Hume
Skepticism	How do you know you are not being deceived about everything?	Perhaps you cannot; suspend judgement	Pyrrho, Sextus Empiricus, Carneades
Pragmatism	What makes a statement true?	Truth is tied to what succeeds in inquiry and practice	C. S. Peirce, William James, John Dewey
Utilitarianism	If an act produces the best outcome, can it be wrong?	No: the right act is the one with the best outcome	Jeremy Bentham, John Stuart Mill, Peter Singer
Kantianism	Are some things wrong even when they would do good?	Yes: act only on principles you could will as universal law	Immanuel Kant, Christine Korsgaard
Stoicism	Should ethics ask what to do, or who to be?	Who to be: virtue is the only good, and externals are indifferent	Zeno of Citium, Chrysippus, Seneca, Epictetus, Marcus Aurelius
Epicureanism	What would make your life go well, apart from being moral?	Pleasure, understood as freedom from pain and anxiety	Epicurus, Lucretius
Existentialism	Does a life need a point, and where would it come from?	None is given in advance: existence precedes essence, so you define yourself by your choices	Jean-Paul Sartre, Simone de Beauvoir; Søren Kierkegaard as forerunner
Absurdism	Does a life need a point, and where would it come from?	None exists, and the right response is lucid persistence, not despair	Albert Camus
Moral nihilism	If everyone approved of torturing children, would it still be wrong?	There are no moral facts; positive moral claims are all false	J. L. Mackie (error theory)
Social contract theory	Could you justify this to everyone it affects?	What is right, or legitimate, is what free parties could agree to	Thomas Hobbes, Jean-Jacques Rousseau, John Rawls, T. M. Scanlon
Marxism	Is history going anywhere?	Yes: it advances through conflicts rooted in how production is organised	Karl Marx
Confucianism	What should I look at to tell whether an act is right?	The role: what this relationship requires of someone in your position	Confucius, Mencius, Xunzi

Schools of philosophy about reality

Schools of metaphysics divide first on What is there? Materialists say only matter: the Greek atomists, and in India the Carvaka school, which also accepted perception as the only source of knowledge. Idealists put mind first, from Berkeley to readers of Yogacara Buddhism. Dualists keep both: Descartes in Europe, and in India Samkhya, which separates pure consciousness from matter.

The older Greek schools can be read the same way. The Pre-Socratics asked what everything is made of and how change is possible. Platonism placed the most real things, the Forms, outside space and time; Aristotelianism brought form back into individual substances; Neoplatonism derived everything from a One beyond being. In the modern period German Idealism made mind and history central, and process philosophy argued that events, not things, are basic — one answer to Is a river a thing, or an event? For more, see the metaphysics guide.

Schools about knowledge: empiricism vs rationalism, and beyond

The famous contest of empiricism vs rationalism is a dispute over Which ways of finding things out actually work? Rationalists such as Descartes, Spinoza and Leibniz held that reason alone can establish substantive truths; empiricists such as Locke, Berkeley and Hume held that every idea derives from experience. Kant’s reply was that experience supplies the content and the mind the structure, so neither side has the whole truth.

India had the same argument, with more parties. Nyaya counted four means of knowledge, Buddhist logicians after Dignāga two, the Mimamsa school five or six, and the Carvaka materialists one: perception.

Other schools of knowledge answer other questions. Skepticism answers How do you know you are not being deceived about everything? Pyrrhonists suspend judgement even on whether knowledge is possible. Pragmatism ties truth to successful inquiry, and logical positivism answered Are metaphysical arguments about anything? by declaring unverifiable claims meaningless. See the epistemology guide.

Schools about how to live: Stoicism, Epicureanism, utilitarianism, existentialism

The ancient schools were schools of life as much as of argument. Stoicism teaches that virtue is the only good and that we are disturbed not by things but by our judgements about them, a theme of Epictetus’s Handbook. Epicureanism seeks tranquillity through simple pleasures, friendship and freedom from the fear of death. Cynicism, after Diogenes of Sinope, showed virtue by living it, often provocatively.

Modern ethical schools mostly answer What should I look at to tell whether an act is right? Utilitarianism looks at outcomes; Kantianism at whether the principle could hold universally; modern virtue ethics at character; care ethics at relationships of dependency; Ubuntu at personhood held in common. Existentialism asks something else: what a life is for when no purpose comes ready-made. See the ethics guide.

Political schools of thought

Social contract theory answers When is political power legitimate, and what may it rightly do? with consent: Hobbes’s bargain from fear, Rousseau’s general will, Rawls’s veil of ignorance. Liberalism puts individual liberty first, though liberals such as Robert Nozick and Ronald Dworkin disagree sharply about property and redistribution. Marxism reads politics through production and class conflict, and critical theory, from Horkheimer and Adorno to Habermas, carried that critique into culture and reason.

Other political schools start elsewhere. Natural law holds that human law answers to what human nature requires, as on Is an unjust law still a law? Ancient Chinese Legalism, with Han Feizi, built order on clear, impartially applied standards rather than the ruler’s virtue that Confucians relied on. Feminist philosophy, from Mary Wollstonecraft to Sally Haslanger, asks whom political categories have left out, and the Latin American philosophy of liberation begins from the excluded.

Religious and theological schools

Many schools grew up to reason about God, scripture and salvation. Scholasticism — Anselm, Aquinas, Duns Scotus, Ockham — used Aristotle’s logic to treat faith and reason as distinct but compatible, the harmonising answer to Can something be known because it was disclosed rather than discovered? Rival answers on that card subordinate reason to revelation, or revelation to reason.

Religious schools also divide on How does a command create an obligation? Does obligation flow from God’s will, from God’s nature, or from a structure that reason can read for itself? And Pure Land Buddhism, with Shinran, holds that liberation comes through the other-power of Amida’s vow rather than one’s own effort, a parallel scholars have often drawn with Christian ideas of grace.

Asian schools of philosophy

Indian, Chinese and Japanese schools are often shelved under “religion” in Western bookshops, but each makes arguments and answers the same kinds of question as any other.

• Vedanta interprets the Upaniṣads on What is there? Adi Shankara’s Advaita says only Brahman is fully real; Rāmānuja makes Brahman a personal God with selves and world as its body; Madhva holds five real and eternal differences.
• Nyaya is the school of logic and debate: four means of knowledge, a five-step model of inference, and Udayana’s argument that the world, being an effect, needs an intelligent maker, on Can argument alone settle whether God exists?
• Madhyamaka, Nagarjuna’s middle way, holds that everything is empty of intrinsic nature because everything arises in dependence on other things. Emptiness is not nothingness.
• Yogacara — Asaṅga, Vasubandhu, Xuanzang — holds that what appears as an external world is given only in consciousness. Whether that is idealism in the Western sense is debated.
• Confucianism is an ethics of roles, ritual and humaneness; its quarrel between Mencius and Xunzi over human nature still sits on Are people naturally good, naturally selfish, or naturally neither?
• Daoism — Laozi, Zhuangzi and later Guo Xiang — speaks of a Dao prior to every name, of spontaneity, and of the limits of any fixed standpoint.
• Mohism, Mozi’s school of impartial care judged by benefit to all, is often called the first systematic consequentialism.
• Neo-Confucianism, from the eleventh century, built a Confucian metaphysics of principle (li) and vital stuff (qi) in answer to Buddhism: Zhu Xi stressed the investigation of things, Wang Yangming innate moral knowing.
• Chan & Zen is Buddhism of direct practice in China and Japan; Dōgen made “just sitting” the heart of practice, and Sen no Rikyū carried its taste for simplicity into the tea ceremony, on Is a mountain beautiful in the same way a painting is?

Smaller schools repay attention: Jainism, with non-injury to all living beings; Abhidharma; Huayan; the School of Names; the Kyoto School. See the guides to Indian and Chinese philosophy.

Islamic schools: Ash’arism, Mu’tazila, falsafa, Illuminationism

• Mu’tazila, the rationalist theologians of the eighth to eleventh centuries, held that moral truths are knowable by reason and bind independently, and that a just God does not command what is wrong.
• Ash’arism, founded by Al-Ash’ari against the Mu’tazila, holds that moral status depends on God’s determination and that created things have no causal power of their own; Fakhr al-Din al-Razi later tested Ibn Sina’s arguments premise by premise.
• Falsafa is philosophy in the Greek manner, written in Arabic: Al-Kindi, Al-Farabi, Ibn Sina and Ibn Rushd, who held that demonstrated truth and revealed truth cannot genuinely conflict.
• Illuminationism is Suhrawardi’s philosophy of light, in which self-knowledge is knowledge by presence rather than by representation.
• Transcendent philosophy is Mulla Sadra’s synthesis, in which existence, not essence, is primary and comes in degrees.

Beside them stand Kalam more broadly, including al-Māturīdī, who allowed reason to recognise some goods without revelation; Sufism, with Ibn Arabi and Rumi; and Islamic jurisprudence, whose reading of law through its purposes appears on How does a command create an obligation? See the guide to Islamic philosophy.

Every school of philosophy on the site

All the schools of philosophy with pages on the site, A–Z, each with its thinkers and conversations:

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