Left-wing politics, leftist politics, and leftism are descriptions within the left–right political spectrum for a range of political ideologies that generally support and seek to achieve social equality and egalitarianism. Left-wing politics typically involve a concern for those in society whom its adherents perceive as disadvantaged relative to others as well as a belief that there are unjustified inequalities that need to be reduced or abolished.

Ideologies considered to be left-wing vary greatly depending on the placement along the political spectrum in a given time and place. At the end of the 18th century, upon the founding of the first liberal democracies, the term Left was used to describe liberalism in the United States and republicanism in France, supporting a lesser degree of hierarchical decision-making than the right-wing politics of the traditional conservatives and monarchists. In modern politics, the term Left typically applies to ideologies and movements to the left of classical liberalism, supporting some degree of democracy in the economic sphere.

Today, ideologies such as social liberalism and social democracy are considered to be centre-left, while the Left is typically reserved for movements more critical of capitalism, including the labour movement, socialism, anarchism, communism, Marxism, Leninism and syndicalism, each of which rose to prominence in the 19th and 20th centuries. In addition, the term left-wing has also been applied to a broad range of culturally liberal and progressive social movements, including the civil rights movement, feminist movement, LGBTQ rights movement, abortion-rights movements, multiculturalism, anti-war movement, and environmental movement, as well as a wide range of political parties.‌

Name The terms left and right that make up the left–right political spectrum were coined during the French Revolution, referring to the seating arrangement in the French National Assembly. The political groups opposed to the royal veto privilege (Montagnard and Jacobin deputies from the Third Estate) generally sat to the left of the presiding member's chair in parliament, while the ones in favour of the royal veto privilege sat on its right.Michel Winock, La Droite, hier et aujourd'hui, tempus, 2012, p. 12.

Usage of the term left became more prominent after the restoration of the French monarchy in 1815, when it was applied to the Independents. The word wing was first appended to left and right factions in the late 19th century, usually with disparaging intent, and left-wing was applied to those who were unorthodox in their religious or political views.

Positions Political philosopher Marius Ostrowski argues that, despite various differences among factions, the left is primarily concerned with who wields power in society and with fighting for "those without" against "those with" who harm "those without". Ostrowski argues that the central value of the left is social equality, which is expressed in fighting for empowerment and against oppression, for parity and against hierarchy, for social recognition of marginalized groups and against discrimination, and for cooperation and against competition. Related concepts include justice, solidarity, cultural pluralism, social progress, and freedom from forceful control or coercion.

Economics

Left-leaning economic beliefs range from Keynesian economics and the welfare state through industrial democracy and the social market to the nationalisation of the economy and central planning, to the anarcho-syndicalist advocacy of a council-based and self-managed anarchist communism. Left-wing politics are typically associated with popular or state control of major political and economic institutions. According to emeritus professor of economics Barry Clark, supporters of left-wing politics "claim that human development flourishes when individuals engage in cooperative, mutually respectful relations that can thrive only when excessive differences in status, power, and wealth are eliminated." From the time of the Industrial Revolution, leftists have often supported trade unions.

Some leftists believe in Marxian economics, named after the economic theories of Karl Marx, but drawing from a range of Marxist and non-Marxist sources. Some distinguish Marx's economic theories from his political philosophy, arguing that Marx's approach to understanding the economy is independent of his advocacy of revolutionary socialism or his belief in the inevitability of a proletarian revolution.

The political relevance of farmers has divided the left. In , Marx scarcely mentioned the subject, though posthumous studies of his notebooks indicate that he was interested in studying the works of agricultural chemists to critique international agricultural trade and natural resource exploitation under capitalism. In other works, including The Communist Manifesto, the Critique of the Gotha Programme, and The Eighteenth Brumaire of Louis Bonaparte, Marx asserts the revolutionary potential of the peasant class through a transfer into the proletariat. Mikhail Bakunin thought the lumpenproletariat was a revolutionary class, while Mao Zedong believed that it would be rural peasants, not urban workers, who would bring about the proletarian revolution.

At the beginning of the 20th century, many leftists advocated strong government intervention in the economy. In contrast, Left-libertarians, anarchists and libertarian socialists believe in a decentralised economy run by trade unions, workers' councils, cooperatives, municipalities and communes, opposing both state and private control of the economy, preferring social ownership and local control in which a nation of decentralised regions is united in a confederation.

Leftists continue to criticise the perceived exploitative nature of globalisation, the "race to the bottom" and unjust lay-offs and exploitation of workers. In the last quarter of the 20th century, the belief that the government (ruling in accordance with the interests of the people) ought to be directly involved in the day-to-day workings of an economy declined in popularity amongst the centre-left, especially social democrats who adopted the Third Way. From the 1990s, the global justice movement, also known as the anti-globalisation movement and the alter-globalisation movement, protests against corporate economic globalisation due to its negative consequences for the poor, workers, the environment, and small businesses.

Environment

One of the foremost left-wing advocates was Thomas Paine, one of the first individuals since left and right became political terms to describe the collective human ownership of the world, which he speaks of in Agrarian Justice. This principle is reflected in much of the historical left-wing thought and literature that came afterwards, although there were disagreements about what this entailed.

Karl Marx and the early socialist philosopher and scholar William Morris had a concern for environmental matters. According to Marx, "[e]ven an entire society, a nation, or all simultaneously existing societies taken together, are not the owners of the earth. They are simply its possessors, its beneficiaries, and have to bequeath it in an improved state to succeeding generations". Following the Russian Revolution, environmental scientists such as revolutionary Alexander Bogdanov and the Proletkult organisation made efforts to incorporate environmentalism into Bolshevism and "integrate production with natural laws and limits" in the first decade of Soviet rule, before Joseph Stalin attacked ecologists and the science of ecology, purged environmentalists and promoted the pseudoscience of Trofim Lysenko during his rule up until his death in 1953. Similarly, Mao Zedong rejected environmentalism and believed that based on the laws of historical materialism, all of nature must be put into the service of revolution.

From the 1970s onwards, environmentalism became an increasing concern of the left, with social movements and several unions campaigning on environmental issues and causes. In Australia, the left-wing Builders Labourers Federation, led by the communist Jack Mundy, united with environmentalists to place green bans on environmentally destructive development projects. Several segments of the socialist and Marxist left consciously merged environmentalism and anti-capitalism into an eco-socialist ideology. Barry Commoner articulated a left-wing response to The Limits to Growth model that predicted catastrophic resource depletion and spurred environmentalism, postulating that capitalist technologies were the key cause responsible for environmental degradation, as opposed to human population pressures. Environmental degradation can be seen as a class or equity issue, as environmental destruction disproportionately affects poorer communities and countries.

Several left-wing or socialist groupings have an overt environmental concern and several green parties contain a strong socialist presence. For example, the Green Party of England and Wales includes an eco-socialist group, the Green Left, founded in June 2005. In Europe, several green left political parties such as the European United Left–Nordic Green Left combine traditional social-democratic values such as a desire for greater economic equality and workers rights with demands for environmental protection. Democratic socialist Bolivian president Evo Morales has traced environmental degradation to capitalist consumerism, stating that "[t]he Earth does not have enough for the North to live better and better, but it does have enough for all of us to live well". Noam Chomsky and Naomi Klein are among those who hold similar views.

In climate change mitigation, the Left is also divided over how to effectively and equitably reduce carbon emissions as the center-left often advocates a reliance on market measures such as emissions trading and a carbon tax while those further to the left support direct government regulation and intervention in the form of a Green New Deal, either alongside or instead of market mechanisms.

Nationalism and anti-nationalism

The question of nationality, imperialism and nationalism has been a central feature of political debates on the Left. During the French Revolution, nationalism was a key policy of the Republican Left. The Republican Left advocated for civic nationalism and argued that the nation is a "daily plebiscite" formed by the subjective "will to live together". Related to revanchism, the belligerent will to take revenge against Germany and retake control of Alsace-Lorraine, nationalism was sometimes opposed to imperialism. In the 1880s, there was a debate between leftists such as the Radical Georges Clemenceau, the Socialist Jean Jaurès and the nationalist Maurice Barrès, who argued that colonialism diverted France from liberating the "blue line of the Vosges", in reference to Alsace-Lorraine; and the "colonial lobby" such as Jules Ferry of the Moderate Republicans, Léon Gambetta of the Republicans and Eugène Etienne, the president of the Parliamentary Colonial Group. After the antisemitic Dreyfus Affair in which officer Alfred Dreyfus was falsely convicted of sedition and exiled to a penal colony in 1894 before being exonerated in 1906, nationalism in the form of Boulangism increasingly became associated with the far-right.