The definition of liberalism has long been the source of disagreement. The tension between its various strands—such as American progressivism, libertarianism and the classical tradition can seem irreconcilable.

Goal was not necessarily to create a comprehensive list of familiar liberal names, but to showcase the ways in which liberalism is, and has always been, a broad church spanning country, party and political affiliation. Also tried to provide a foundation for an illuminating discussion, rather than a merely rancorous one.

Jane Addams, a mainstay of American schoolbooks and a radical social reformer who remains conspicuously absent from the pantheon of liberalism’s most recognisable thinkers; Salvador de Madariaga, a leading post-war architect of the European project; and Ibn Khaldun, who wrote of the importance of the specialisation of labour fully 400 years before Adam Smith. It also prompted us to re-examine the ideas of some of favourites, such as Friedrich Hayek and John Rawls.

Putting Ayn Rand, William Beveridge and Immanuel Kant into conversation with one another has led to consider what such divergent writers have in common. In other words, what makes them liberal? A few themes emerge: a commitment to individual rights, an aversion to the status quo and a faith in progress. Liberalism has evolved, and will continue to do so. That ability to adapt and encompass a range of beliefs is a great strength. But only because it exists alongside a second critical component: an insistence on open debate and self-examination. It is this second feature that enables liberalism’s bad ideas to be pruned and the good to be cultivated.

1. Thomas Hobbes (1588-1679)

Main work: “Leviathan”, 1651

Known for: Among the earliest of a handful of writers to set out principles for liberalism.
Because the natural state of man is “solitary, poor, nasty, brutish and short,” liberty for an individual is tied to the power of a sovereign, administering through laws, within a commonwealth. His detailed construction became the foundation for numerous other works examining the proper role and structure of government.

2. John Locke (1632-1704)

Main works: “A Letter Concerning Toleration”, 1689, and “The Second Treatise of Government”, 1689

Known for: Expanded on Hobbes to provide the architecture for a modern liberal state. In “A Letter” Locke argues, contrary to Hobbes, for the state to tolerate different religious beliefs. In his “Second Treatise”, he echoes Hobbes’s view of the need for strong government, writing: “where there is no law, there is no freedom”. But, rather than endorse Hobbes’s all-powerful Leviathan, Locke thought that the system should separate those who make laws from those who execute them.

3. Charles de Secondat, Baron de Montesquieu (1689-1755)

Main work: “The Spirit of the Laws”, 1748

Known for: Montesquieu devised the tripartite structure of government adopted by America. His monumental work provides guidance on how governments should be structured “by fallible human beings” to serve “the people for whom they are framed” with the most liberty that would be feasible. To accomplish this requires limits: “Liberty is a right of doing whatever the laws permit, and if a citizen could do what they forbid he would no longer be possessed of liberty.”

Influenced: Many citations in the Federalist Papers in essays by James Madison and Alexander Hamilton.

4. Thomas Paine (1737-1809)

Main work: “Common Sense”, 1776

Known for: In just a few dozen pages of argument, Paine creates the intellectual catalyst for the American Revolution. The work received immediate, widespread circulation in America and then in other countries. “Government,” Paine argues, “is a necessary evil”, inevitably restricting liberty. He attacked both hereditary rule and monarchy, proposing instead a government of elected representatives and a limited, rotating presidency.

Influenced: Revolutionaries in America and elsewhere—until they become the government themselves.

5. Adam Smith (1723-1790)

Main work: “The Wealth of Nations”, 1776

Known for: Smith laid the intellectual foundation of modern economics, markets and free trade. His assertion that an “invisible hand” is at the heart of the market is among the most cited phrases in economics. But he also explored the division of labour, the benefits of trade, the mobility of capital, the rigging of markets by businesses and government, and public goods (notably universal education).

6. Olympe de Gouges (Marie Gouze) (1748-1793)

Main Work: “Declaration of the Rights of Woman and the Female Citizen”, 1791

Known for: Gouges is often heralded as a founder of modern feminism. Her “Declaration” is a response to “The Declaration of the Rights of Man and of the Citizen”, drafted by the Marquis de Lafayette, Thomas Jefferson, and Honoré Mirabeau, which did not extend the natural rights of the citizen to women as well as men. Gouges was a prolific defender of free speech, women’s rights and political dialogue, as well as an abolitionist and pacifist. She was executed by guillotine for her support of constitutional monarchy at the beginning of Maximilien Robespierre’s “reign of terror” in 1793.

Influenced: Mary Wollstonecraft, Sophie and Nicolas de Condorcet and the Girondins, a group of French republicans during and after the revolution.

7. Mary Wollstonecraft (1759-1797)

Main Work: “A Vindication of the Rights of Woman”, 1792

Known for: Wollstonecraft’s treatise is considered by many to be the first feminist manifesto. Others grapple over whether her writings, which critique excessive emotion and female sexuality, are indeed feminist. “A Vindication” contains endless references to the paragon of rational thought, and a vehement defence of the importance of equal educational opportunities for men and women.

Influenced: Thomas Paine, Elizabeth Cady Stanton, Susan B. Anthony, Virginia Woolf.

8. John Stuart Mill (1806-1873)

Main Work: “On Liberty”, 1859

Known for: Mill has become a reference point for liberalism. “On Liberty” is a defence of individual freedom with a caveat: “The only purpose for which power can be rightfully exercised over any member of a civilized community, against his will, is to prevent harm to others.” Mill views even a society under representative government to threaten liberty, notably, in a term he popularised, the “tyranny of the majority”.

Influenced: An inevitable citation in debates about liberalism.

9. Baruch (Benedict) de Spinoza (1632-1677)

Main political work: “Theological-Political Treatise”, 1670

Known for: A polymath beloved today but often reviled in his own time, Spinoza earned his living grinding lenses and his fame by changing how people saw the world. While accepting the existence of an absolute sovereign, he argued that freedom of thought, speech and academic inquiry should not only be permitted by the state, but were essential for its survival.

Influenced: Jean-Jacques Rousseau, Friedrich Nietzsche.

10. Alexis de Tocqueville (1805-1859)

Main work: “Democracy in America”, 1835

Known for: His study of America remains at the heart of ongoing debates over questions with vast importance, including how to ensure democracy and individual liberty coexist. His conclusion was that America’s success stemmed from devolving responsibility to the most local of all organisations, often voluntary, an approach now threatened by the centralisation of resources and authority in Washington, DC.

Influenced: John Stuart Mill, Friedrich Hayek.

11. Frédéric Bastiat (1801-1850)

Main work: “The Law”, 1850

Known for: “Everyone wants to live at the expense of the state,” Bastiat wrote. “They forget that the state lives at the expense of everyone.” He was an incisive debunker of flawed reasoning in support of government policies that come at the cost of individual freedom. His definition of “legal plunder” (if the law takes from one to give to another) remains a living sentiment for those who resist state expansion, as does his definition of what comprises good economic policy: it must be judged on not only what would be produced but what would be lost—the innovations and activities that do not occur.

Influenced: Gustave de Molinari, Ludwig von Mises, Libertarians.

12. Harriet Taylor Mill (1807-1858)

Main work: “The Enfranchisement of Women”, 1851

Known for: Though little was published under Taylor Mill’s own name, her second husband, John Stuart Mill, readily admitted the influence she had on him and his work. They were an intellectual duo to be reckoned with. Taylor Mill wrote anonymously or under a pseudonym on the nature of marriage, sex and domestic violence. She was a fierce advocate of women’s suffrage, writing along with her husband, “It is neither necessary nor just to make imperative on women, that they shall be either mothers or nothing.”

Influenced: John Stuart Mill, suffragists.

13. Jane Addams (1860-1935)

Main work: “Democracy and Social Ethics”, 1902

Known for: An important voice during the progressive era and a radical for her time, Addams would probably feel at home among American liberals today. She argued that democratic processes should not belong to a separate, elite political sphere, and that democracy is, at its core, local, accessible and integral to everyday life. Addams wanted to scale up the idea of liberty so that it encompassed entire societies. “Surely the demand of an individual for decency and comfort”, she wrote, “may be widened until it gradually embraces all the members of the community.”

Influenced: John Dewey, George Herbert Mead and “pragmatic liberalism”.

14. Salvador de Madariaga y Rojo (1886-1978)

Main work: A principal author of the Oxford Manifesto, 1947

Known for: Madariaga led a group of representatives from 19 countries in drawing up a charter laying out the fundamental principles of liberalism, as they defined it: a commitment to individual liberty, economic freedom, the free exchange of ideas and international coalition-building. Madariaga and his contemporaries worried that the death and destruction of the world wars were caused largely by the abandonment of these ideals. But he believed equality and liberty did not necessarily go hand in hard, writing in 1937 that “inequality is the inevitable consequence of liberty,” which may explain why “security” and “opportunity” were written into the manifesto as “fundamental rights”.

Influenced: The founders of the European Union.

15. Immanuel Kant (1724-1804)

Main works: “Critique of Pure Reason”, 1781; “Perpetual Peace: A Philosophical Sketch”, 1795

Known for: Kant favoured republican governments over majoritarian ones. He worried that rule by majority could undermine the freedom of individuals, and called direct democracy a kind of “despotism” of the masses. He argued that lasting international peace could only be realised through a “political community” of countries committed to what came to be known as “Rechtsstaat”, or the constitutional state. Kant’s faith in the supremacy of law and the social contract seems to be derived from his thinking on moral philosophy. Kant says that free will requires individuals to “self-legislate”, or police themselves, so that they act morally. If we scale up that idea, then having political freedom means entire societies must do the same, preferably—if it were up to Kant—with a constitution.

Influenced: Karl Leonhard Reinhold, G.F.W. Hegel, Michel Foucault, Jürgen Habermas, John Rawls and too many others to list.

16. José María Luis Mora (1794-1850)

Main work: “Political Catechism of the Mexican Federation”, 1831

Known for: A priest, journalist and politician in newly independent Mexico, the “father of Mexican liberalism” advocated for religious freedom and secular education. He believed individual liberties needed protecting from the state—and from the people. Perhaps most importantly, his ideas helped spark La Reforma, a sweeping reform movement that began in the 1850s with the principle aims of reducing the privileges enjoyed by the church and the army, and transforming Mexico into a modern “representative republic”.

Influenced: 19th-century Mexican liberals.

17. Harriet Martineau (1802-1876)

Main works: “Illustrations of Political Economy”, 1832-1834; “Society in America”, 1837

Known for: Half-way between a novel and a political treatise, Martineau’s “Illustrations” argued that economics was the least understood science and the one most integral to the wellbeing of society. Initially a non-interventionist, Martineau came to believe that governments should intervene in the interest of curbing inequality—unsurprising conclusions if one considers her reputation as a feminist and abolitionist. Like Tocqueville, she made one of the first sociological studies of America.

Influenced: John Stuart Mill, Harriet Taylor Mill, Émile Durkheim, James Madison.

18. John Maynard Keynes 1883 - 1946

Main political work: “The General Theory of Employment, Interest and Money”, 1936

Known for: The father of the economic theory that bears his name, Keynes belonged to a new breed of 20th-century liberal that believed in accomplishing collectively what could not be achieved individually. In his “General Theory”, Keynes lays the case for heavily guided capitalism and comprehensive economic planning by government. In a turn away from laissez-faire liberalism, Keynesianism became a central organising principle of developed economies following the Great Depression.

Influenced: Economic planning after the Great Depression, and everything from the New Deal to post-2008 stimulus packages.

19. William Beveridge (1879-1963)

Main Work: The Beveridge Report, 1942

Known for: Beveridge’s report provides the initial outline of Britain’s National Health Service, intended, he said, to provide each person with care to the limits of what science could provide. With the support of the state, he believed people would be free to have full lives and contribute in greater ways—a true liberty and benefit for society. His commitment to the welfare state, and background in the Liberal Party, made Beveridge the archetype of the benign interventionist. Others saw his work as mere socialism. Adding to the debate was his nuanced view of the ownership—or non-ownership—of private property. Beveridge justified private control of productive assets not on principle, but because that had been effective in the past. He noted that the value of private property can be overstated, and in his productive career, the only private property he found to be necessary was a fountain pen.

Influenced: Britain’s Liberal Party, European social democracy.

20. Ayn Rand (1905-1982)

Main works: “The Fountainhead”, 1943; “Atlas Shrugged”, 1957

Known for: Rand launched a brutal attack on the morality of a Western liberalism that criticises self-interest. “Atlas Shrugged”, a political screed presented as a romance, remains a staple of best-seller lists and perhaps the single most influential clarion call for anti-state individualism. Her uncharitable view of human frailty and the trials imposed by the unfairness of life makes her an incendiary figure on the left. But echoes of her writing are heard in the endless political obfuscation about causes and solutions. Her thesis, that a cynical pursuit of altruism undermines self-esteem, innovation, evolution and broad prosperity, resonates as—or perhaps because—public support for socialism grows.

Influenced: American conservatives and libertarians.

21. Friedrich Hayek (1899-1992)

Main works: “The Road to Serfdom”, 1944; “The Fatal Conceit: The Errors of Socialism”, 1988; “The Constitution of Liberty”, 1960

Known for: Hayek was the person most cited by readers after the publication of our initial bibliography. This reflects how powerfully he continues to resonate in the political debate about government. Hayek was not an absolute libertarian, and he allowed for government to provide some assistance, but he remains a controversial figure on the left because of how marginal those concessions were. He argued that the expanded presence of the state created a corrosive force that ended in the loss of individual freedom and prosperity. The strongest antipathy to his views, however, may be found among his fellow economists, because he argued that information was too scattered for either a state or an individual to make realistic assumptions or centralised plans. Read more about Hayek in our series on great liberal thinkers.

Influenced: John Maynard Keynes, Thatcherism.

22. Ibn Khaldun 1332-1406

Main work: The Muqaddimah, 1377

Known for: In his magnum opus, Khaldun made a careful study of sociology, politics, urban life, economics and knowledge. His career spans cities (Tunis, Seville, Granada, Fez, Cairo, Damascus) empires and disciplines. He is widely credited for his theory on the cyclical nature of empires in which “asabiyyah”, social cohesion or tribalism, plays a role in bringing groups to power and then tearing them apart—a phenomenon that was true in the 14th century and remains true in modern party politics. Some 400 years before Adam Smith, Khaldun warned that excessive bureaucracy could hamper labour specialisation. His early influence and writings on the political economy have caused some academics to call Khaldun the “father of economics” in Smith’s stead.

Influenced: Ottoman historians, Enlightenment thinkers, Joseph Schumpeter.

23. Anders Chydenius (1729-1803)

Main political work: The National Gain, 1765

Known for: A priest and philosopher, Chydenius’s work included pamphlets and reports on freedom of speech, freedom of religion and free trade. In “The National Gain” he outlined a comprehensive case for free markets—eleven years before Adam Smith’s “The Wealth of Nations”. Society functioned at its best when it was allowed to operate freely, Chydenius reasoned. This philosophy also gave rise to one of the world’s first laws ensuring freedom of the press, which, as a member of Sweden’s parliament, Chydenius helped introduce in 1776.

Influenced: Nordic liberalism.

24. Hannah Arendt (1906-1975)

Main work: The Origins of Totalitarianism, 1951

Known for: In a chapter of Arendt’s “Origins”, she lays out a paradox that divides liberals of all stripes even today. Especially today. “The Decline of the Nation-State and the End of the Rights of Man”, explores the tensions between “natural rights”, or human rights which are supposedly inalienable, and “civil rights”, which depend on citizenship. To Arendt, the gap between the two is obvious when examining the plight of refugees. Stateless people, she argues, must rely on others’ respect for human rights to secure their safety. But the maltreatment of refugees beginning after the first world war, in Arendt’s telling, would suggest that these natural rights are meaningless when pitted against the sovereignty of the states that would host them. In short, borders matter.

Influenced: Jürgen Habermas, 20th-century political philosophy.

25. Isaiah Berlin (1909-1997)

Main political work: Two Concepts of Liberty, 1958

Known for: Berlin defined a crucial faultline in liberal thinking when it came to individual freedom. He recognised that the gulf between “positive” and “negative” liberty would lead to divergent definitions of liberalism—and indeed it has. Negative liberty is best defined as freedom not to be interfered with. Positive liberty empowers individuals to live fulfilling lives, even if that requires interference from government; for example, in the form of education provided by the state. But positive liberty is ripe for exploitation, Berlin reasoned, and may allow government to force its goals upon citizens in the name of freedom—enabling totalitarianism.

Influenced: John Rawls, Judith Shklar.

26. John Rawls (1921-2002)

Main work: A Theory of Justice, 1971

Known for: One of the most influential political philosophers of the 20th century, Rawls used a thought experiment, “the veil of ignorance”, to make the case for a philosophy he dubbed “justice as fairness”. If you were dreaming up an ideal society, Rawls argued, but didn’t know what lot you would be dealt, it would be in everyone’s self-interest to ensure equality of opportunity and shared wealth. Today, the veil of ignorance is commonly used to argue for more redistribution, but Rawls noted an important caveat: that inequality in distribution was permissible if it benefited the least well off in society. That sentiment would be shared by many who resist the growth of redistributive policies that undermine economic vitality, and hence the opportunities of the most vulnerable.

Influenced: Judith Shklar, Robert Nozick, big-government American liberalism.

27. Robert Nozick (1938-2002)

Main work: “Anarchy, State and Utopia”, 1974

Known for: Though they are both considered liberals, Nozick was the anti-Rawls. He found much to dislike in Rawls’s theory of redistributive justice, arguing that people owned their talents. Successes belonged only to the individuals to whom they were attributed, not to society writ large. Nozick’s small-government liberalism was echoed in the policies of Margaret Thatcher and Ronald Reagan in the 1980s. Liberty, Nozick said, disrupts patterns. Justice cannot demand some preferred distribution of wealth. Read more on Berlin, Rawls and Nozick in our series of philosophy briefs.

Influenced: Modern small-government conservatives.

28. Judith Shklar (1928-1992)

Main work: The Liberalism of Fear, 1989

Known for: Shklar viewed limited, democratic government as a necessary defence that shields people, especially the poor and weak, from the abuses of the state and its agents—such as the armed forces and the police. She saw freedom from cruelty and the division of powers as the twin pillars of her “liberalism of fear”. In her attempts to define this slippery ideology, she argued that a “liberal era” that truly upheld the notion of equal rights did not really exist in America until after the civil war. Liberalism, Shklar wrote, “was powerful in the United States only if black people are not counted as members of its society.” As a rebuke to critics who called her theory reductionist, Shklar asked why, in discussions of political philosophy, emotions must always play second fiddle to “causes”.

Influenced: John Rawls (her colleague at Harvard), Amy Gutmann, Patrick T. Riley.