John Rawls's Political Liberalism explained: overlapping consensus, public reason and shared institutions

John Rawls became famous in 1971 with A Theory of Justice, the book that made justice as fairness the starting point of modern political philosophy. Twenty-two years later he published a second major book that rethinks the first. Political Liberalism came out in 1993; Columbia University Press issued an expanded edition in 2005 that adds his essay "The Idea of Public Reason Revisited". In Spain, Crítica publishes it as El liberalismo político, translated by Antoni Domènech.

The reason for the rethink is honest and instructive. A Theory of Justice imagined a well-ordered society in which everyone accepted the same moral outlook, justice as fairness included. Rawls came to see that this can't happen in a free country. Give people freedom of thought and conscience and they will reach different conclusions about God, the meaning of life, right and wrong, and they will keep reaching them. He called this the fact of reasonable pluralism, and the Internet Encyclopedia of Philosophy summarises his view that it is a permanent feature of any liberal, non-repressive society.

So the book asks a new question, which Rawls states near the start: how is it possible for a just and stable society of free and equal citizens to exist over time when they remain profoundly divided by reasonable religious, philosophical and moral doctrines?

The burdens of judgment

Rawls's first move is to explain why reasonable people disagree. He calls the sources of that disagreement the burdens of judgment. In the Stanford Encyclopedia's summary, the deepest questions of religion, philosophy and morality are very hard to think through, and the Internet Encyclopedia of Philosophy adds that these burdens make reasoned agreement on whole worldviews very unlikely. Disagreement is what you should expect from free people thinking carefully, and treating opponents as fools or villains misreads the situation.

A political conception of justice

His second move is to separate two things. Each citizen has what Rawls calls a comprehensive doctrine, a whole view of life, religious or secular. A political conception of justice is narrower. It covers only the basic structure of society, the constitution and the main institutions, and it is freestanding: its content is set out independently of any comprehensive doctrine. It is built from ideas already present in a democracy's public political culture, starting with the idea of citizens as free and equal.

A Catholic, a secular humanist and a Muslim can then all accept it, each for reasons rooted in their own beliefs.

Overlapping consensus, not a truce

That is the overlapping consensus, the best-known idea in the book. In the Stanford Encyclopedia's phrasing, citizens all endorse a core set of laws for different reasons. Rawls contrasts it with a modus vivendi, a mere balance of power between rival camps. A truce holds while neither side can win; when the balance shifts, the stronger side rewrites the rules. An overlapping consensus is sturdier because each group supports the institutions on its own grounds, whoever happens to be winning.

From this comes his principle of legitimacy. Political power is fully proper only when it is exercised in accordance with a constitution whose essentials all citizens may reasonably be expected to endorse.

Public reason

The last piece is public reason. When citizens debate fundamental political questions, and above all when judges, officials and candidates do, they should justify their positions with reasons that others can reasonably accept, without resting everything on their own religion or philosophy. For Rawls this is a moral duty of civility, and the law doesn't enforce it.

This is the most contested part of the book. Jürgen Habermas argued in a 1995 exchange that Rawls did not take democratic autonomy seriously enough and gave liberal rights a priority that demoted the democratic process. Religious critics have argued that public reason is less neutral than it claims and asks believers to leave their deepest reasons at the door. Perfectionists hold that the state may legitimately promote some ways of life as better than others. The debate is still running, and the Stanford Encyclopedia's entry on public reason is the best map of it.

What radical centrism takes from Rawls

We have already set Rawls against Amartya Sen, who prefers comparing real options to designing ideal justice; that piece concluded that Rawls supplies the rules for deciding together and Sen the method for choosing reforms. Political Liberalism is the book that does the first job.

Each tradition finds itself in it. The left takes the conviction that citizens are free and equal and that the basic institutions must be fair to all of them, including the worst off. The right and the liberal tradition take a state that does not impose any single doctrine of the good life, with liberty of conscience and rule-bound government first. The idea that belongs to neither camp is the overlapping consensus: deep opponents can back the same institutions for their own different reasons, and that support lasts longer than a truce.

That matters for this week's subject. Spanish politics often runs like a modus vivendi between two blocs: rules for appointing judges or regulators that each side accepts only while it can win them. Rawls tells us what to aim for instead, institutions whose design both blocs can defend from inside their own convictions, the left because they protect equal citizens, the right because they limit government. We turn that into concrete rules in today's proposal on two iron blocs and rules that reward agreement.