Political Theory: Justice, Power, Legitimacy and Liberty

A traffic light turns red at 3 a.m. on an empty street, and you stop. Nobody is watching. Why? Because it is the law, because it is sensible, because everyone else stops, because someone could be coming. Now scale that up: why do millions of people hand over a slice of their pay every year, accept a verdict from a stranger in a robe, or send their sons and daughters to fight when an official signs a paper? Political theory is the study of that ordinary miracle, and of whether it is justified.

It is not the same as political science that counts votes. It asks what a government is for, when it has the right to command, and what we owe each other. The strongest answers come from every continent, and a good course reads them side by side rather than treating Europe as the default.

Why have a state at all? Nature, contract and the fish

Start from a thought experiment: no government. What would life be like? Thomas Hobbes, writing during the English civil war, said in Leviathan (1651) it would be a "war of all against all", with life "solitary, poor, nasty, brutish, and short". Not because people are wicked, but because they fear each other, and the safest move against a fearful neighbour is to strike first. The only escape is to give up your freedom to a sovereign strong enough to keep everyone in awe.

The same worry appears elsewhere. The Indian tradition of statecraft speaks of matsya-nyaya, "the law of the fishes", where the big fish eat the small. Kautilya's Arthashastra (attributed to the Mauryan minister of about 300 BCE; Patrick Olivelle's 2013 translation argues the text took its present shape around the first century CE from older material) makes the king, and his rod of punishment, the cure. Ibn Khaldun, in the Muqaddimah (1377), argued that people need a restraining authority because aggression is natural to them. Aristotle in his Politics disagreed in a different way: humans are by nature political animals who flourish only in a community, so the state is not an invention but a fulfilment.

The social contract tradition says a state is justified by an agreement, real or imagined. John Locke (Second Treatise, 1689) thought people in nature already have rights to life, liberty and property, and form governments to protect them, so a government that violates them may be resisted. Jean-Jacques Rousseau (The Social Contract, 1762), opening with "Man is born free, and everywhere he is in chains", argued legitimacy comes only from the general will of the people governing themselves. Hobbes wanted a strong sovereign; Locke a limited one; Rousseau a self-governing one.

Hobbes's logic is a game you can run. Each person chooses to keep the peace or to grab. If everyone keeps the peace each gets 3; a grabber facing a peaceful person takes 4 and leaves them 0; two grabbers fight and each get 1. Grabbing wins in every pairing, so peace collapses. Now add a sovereign who punishes grabbers. How much punishment is enough?

The answer is neat: an expected penalty above 1 is enough, whatever the starting mix, because it removes the temptation exactly. But notice what the toy leaves out. Who punishes the sovereign? That is Locke's question, and the reason constitutions limit power.

Who should rule, and for whose sake?

Plato's Republic (about 375 BCE) answered: those who know. Rule should belong to philosopher-guardians trained to see the good, as a ship should be steered by a navigator, not by a vote of the crew. Aristotle's Politics asked two more practical questions of every regime. How many rule: one, few or many? And for whose benefit: the common good, or the rulers' own? Combine them and you get six constitutions, three good and three corrupted.

Notice the question under Aristotle's grid: not "who is in charge?" but "is power used for everyone?" Other traditions ask the same. Confucius (551 to 479 BCE) held that government begins with the ruler's own conduct; a leader who is himself upright needs few orders. Mencius, his follower, said the people matter most, the state next, the ruler least, and that a ruler who abuses the people loses the Heaven-given mandate to rule, an idea that justified rebellion in Chinese history. Kautilya's king serves the welfare of his subjects, whose happiness is his, though the Arthashastra is frank about spies, deception and war in a way that Confucian texts avoid. Machiavelli, centuries later, separates what rulers should be from what they must do to keep power. Each of these is a view about the same two variables.

Why people obey: power, legitimacy and the tipping point

Power is the ability to make others do things. Legitimacy is the belief that the power is rightful. Max Weber, in lectures of 1919 (Politics as a Vocation), defined the state as the body that claims the monopoly of legitimate force within a territory, and gave three sources of legitimacy: tradition ("it has always been so"), charisma (a leader's personal appeal) and legal-rational rules (offices and procedures). Ibn Khaldun added a cycle: a dynasty rises on asabiyya, the solidarity of a tight group, then its rulers grow comfortable, solidarity fades, and after about three generations, which he counted as roughly 120 years, a hardier group replaces it.

Legitimacy is not only a feeling. It works as a prediction about everyone else. Mark Granovetter's threshold model (1978) says each person has a threshold: they will join a protest if enough others already have. Some people join first at nothing; some join at ten others; some need half the street. Whether a crowd tips depends on the whole distribution, not the average. The economist Timur Kuran used this idea to explain why East Germany's regime seemed stable until the autumn of 1989 and then fell.

The moral of the model is that a regime's support can be much thinner than it looks, and also that a crowd's size can hide how fragile it is. Legitimacy lives in expectations about other people, which is why regimes work hard at appearing strong, and why sudden changes surprise even the people living through them.

Liberty: where does my freedom end?

John Stuart Mill's On Liberty (1859) gave the most famous rule: the only purpose for which power can rightfully be used against a member of a community, against their will, is to prevent harm to others. Their own good, physical or moral, is not a sufficient warrant. This is the harm principle. Isaiah Berlin (1958) sorted freedom into negative liberty (freedom from interference) and positive liberty (the capacity to run your own life), warning that talk of the "real self" can excuse tyranny. Philip Pettit and the republican tradition, from Rome to Madison, defined freedom as non-domination: you are unfree if someone merely can interfere at will, even if they are kind. Confucian thought sees the person as made by relationships and duties, so freedom detached from role and community seems thin. Nozick treats each person as the owner of their body and property.

These lenses give different answers to concrete questions. Choose a case below. The answers are how a thinker in each tradition would typically reason, our extrapolation, not quotations.

The point is not to find the winning lens but to see that people who agree on "freedom is important" can disagree on a helmet law for honest reasons: they are counting different things.

Justice: the veil, the entitlement and the flute

John Rawls (A Theory of Justice, 1971) asked what rules we would choose for society if we did not know our place in it: rich or poor, clever or slow, man or woman, believer or not. Behind this veil of ignorance, he argued, we would choose equal basic liberties and allow inequalities only if they work to the benefit of the least advantaged: the difference principle. He thought a cautious chooser would follow the "maximin" rule, maximising the worst outcome. John Harsanyi replied that a rational chooser would maximise the average instead. The truth may lie between, and your own fear of the bottom sets where.

Robert Nozick, in Anarchy, State, and Utopia (1974), objected from another direction. Justice is not a pattern of shares but a history of how they came about: if holdings were acquired fairly and transferred freely, the result is just, whatever it looks like. His example: start from any distribution you like, and suppose a million fans each freely pay 25 cents to watch the basketball star Wilt Chamberlain play. He ends up rich. To keep the pattern you would have to keep stopping free exchanges. Critics replied that markets rest on rules the community sets (Rawls's "background justice"), and that G. A. Cohen argued the freedom of the poor is also reduced by the property system.

Amartya Sen (The Idea of Justice, 2009) came at it from a third angle. We do not need a perfect blueprint of a just society to know that famine or slavery is unjust; we need ways to compare real options. He asks what people are actually able to do and be (their capabilities), not only what they own. His example: three children quarrel over a flute. The first can play it, the second is poor and has no toys, the third made it. A utilitarian, an egalitarian and a libertarian each have a good reason to pick a different child, and none is simply wrong. Sen's moral is that plural, reasoned argument matters more than a single formula.

Whose voices were left out of the contract?

Great theories have blind spots, and some of the best political theory is the critique of the blind spots. Mary Wollstonecraft's A Vindication of the Rights of Woman (1792) argued that women's supposed unfitness for citizenship was produced by an education built to make them pleasing instead of rational, so the argument for equal rights applied to them too. Mill's The Subjection of Women (1869) made the same case from liberal premises. Karl Marx and Friedrich Engels (Communist Manifesto, 1848) argued that the question "what is a fair contract?" hides that workers must sell their labour to survive, so political equality can coexist with deep economic unfreedom; defenders of markets reply that Marx's predictions failed and that voluntary exchange raises the poorest. (31 Political Economy covers that debate.)

Carole Pateman (The Sexual Contract, 1988) and Susan Moller Okin (Justice, Gender, and the Family, 1989) asked why theories of justice rarely examined the household. Charles Mills (The Racial Contract, 1997) argued that the social contract was in practice a contract among whites that excluded others. Communitarians such as Michael Sandel (Liberalism and the Limits of Justice, 1982) said Rawls's chooser, stripped of identity, is not a real person. Gandhi's Hind Swaraj (1909) questioned whether modern states, even self-governing ones, deliver freedom. These challenges did not end the older traditions, which have replies; they widened the conversation about who counts.

What a graduate just sees

• Every government answers four questions (who rules, why we obey, how free, how fair), whether it says so or not.
• A state can be justified as nature's fulfilment (Aristotle), a bargain (Hobbes, Locke), a general will (Rousseau), or a protector (Kautilya). Each carries a different limit on power.
• Ask "how many rule, and for whom?" before arguing about names. Aristotle's two questions still sort most regimes.
• Legitimacy is a belief about what others believe. Regimes can look stable and be brittle, as in a threshold cascade.
• "Freedom" has at least three meanings (no interference, capacity, no domination), and people can honestly disagree while using the same word.
• Justice theories answer differently: a fair procedure (Rawls), a fair history (Nozick), or fair real options (Sen). Ask which one an argument is using.
• A thought experiment is a tool for isolating a variable, and its strength depends on what it assumes away.
• Who is left out of a theory is as informative as who is in it.

Where it shows up next

• Comparative Politics (35/13): Aristotle's grid becomes the study of presidential and parliamentary systems, democracies and autocracies; Weber's legitimacy becomes the question of why some regimes last.
• Constitutional Law (35/03) and International Law & Human Rights (35/10): Locke's limits and Mill's harm principle live on in bills of rights and proportionality tests.
• Political Economy (35/17): Rawls, Nozick and Marx are the three poles of the argument about markets and fair shares.
• In the world and in books: every constitutional debate, every tax argument, and every novel about a tyrant or a rebellion. Literature students find these arguments in dystopias and in epics from the Mahabharata to Orwell.

If you want to go deeper

• 📘 Textbook. Will Kymlicka, Contemporary Political Philosophy: An Introduction (Oxford, 2nd edition, 2002). The classic survey of utilitarianism, liberal equality, libertarianism, communitarianism, feminism and multiculturalism.
• 📘 Textbook. Adam Swift, Political Philosophy: A Beginners' Guide for Students and Politicians (Polity; later editions). Clear and problem-led.
• 📘 Gentler. Michael Sandel, Justice: What's the Right Thing to Do? (2009). Everyday dilemmas leading into the big theories.
• 🌐 Free course. Yale Open Courses, PLSC 114 Introduction to Political Philosophy (Steven B. Smith): Plato to Rawls, with lectures and transcripts. Also Sandel's Justice course from Harvard.