In Western usage, the term "communist state" is often used in reference to single-party socialist states governed by parties adhering to a variant of Marxism–Leninism, though these states officially refer to themselves as "socialist states" or states that are in the process of building socialism and do not describe themselves as "communist" or as having achieved communism. Aside from the "communist states", a number of other states have described their orientation as "socialist" in their constitutions. A socialist state is to be distinguished from a multi-party liberal democratic state governed by a self-described socialist party, where the state is not constitutionally bound to the construction of socialism. In such cases, the political system and machinery of government is not specifically structured to pursue the development of socialism.
The concept of a socialist state is closely related to "state socialism", the political view that a socialist system can be established through the use of state action or government policies. As such, the concept of a socialist state is usually advocated by Leninists and Marxist–Leninists, but rejected as being either unnecessary or counterproductive by some classical Marxists, libertarian socialists and political thinkers who view the modern state as a byproduct of capitalism which would have no function in a socialist system and as a result cannot be used to construct socialism. In the Marxist–Leninist view, a "socialist state" is a state under the control of a vanguard party that is organizing the economic, social and political affairs of the country toward the realization of socialism. The vanguard party presides over a state capitalist economy structured upon state-directed capital accumulation, with the goal of building up the country's productive forces and promoting worldwide socialist revolution, with the eventual long-term goal of building a socialist economy.
The pre-Marxist Utopian socialist thinker Henri de Saint-Simon believed that the nature of the state would change under socialism from that of political rule (via coercion) over people to a scientific administration of things and a direction of processes of production. Specifically, the state would become a coordinating entity for production as opposed to a mechanism for political control. According to Friedrich Engels, Saint-Simon foreshadowed the classical Marxist notion of the development of the state in a socialist society.
Karl Marx understood the state to be an instrument of the class rule, dominated by the interests of the ruling class in any mode of production. Although Marx never referred to a "socialist state", he argued that the working-class would have to take control of the state apparatus and machinery of government in order to transition out of capitalism and to socialism. This transitional stage would involve working-class interests dominating government policy (the "Dictatorship of the proletariat"), in the same manner that capitalist-class interests dominate government policy under capitalism (the "Dictatorship of the bourgeoisie"). Friedrich Engels argued that as socialism developed, the state would change in form and function: under socialism it is not a "government of people, but the administration of things"; and thus would cease to be a state by the traditional definition.
One of the most influential modern visions of a socialist state was based on the Paris Commune, in which the workers and working poor took control of the city of Paris in 1871 in reaction to the Franco-Prussian War. Karl Marx described the Paris Commune as the prototype for a revolutionary government of the future, "the form at last discovered" for the emancipation of the proletariat. Friedrich Engels noted that "all officials, high or low, were paid only the wages received by other workers... In this way an effective barrier to place-hunting and careerism was set up". Commenting on the nature of the state, Engels continued: "From the outset the Commune was compelled to recognize that the working class, once come to power, could not manage with the old state machine". In order not to be overthrown once having conquered power, Engels argues, the working class "must, on the one hand, do away with all the old repressive machinery previously used against it itself, and, on the other, safeguard itself against its own deputies and officials, by declaring them all, without exception, subject to recall at any moment."  Such a state would be a temporary affair, Engels argued. A new generation, he suggested, brought up in "new and free social conditions", will be able to "throw the entire lumber of the state on the scrap-heap."
The Leninist conception of a socialist state is tied to Vladimir Lenin's theory of the revolutionary party and organizational principles of democratic centralism. Adapted to the conditions of semi-feudal Russia, Lenin's concept of the "dictatorship of the proletariat" involved a revolutionary vanguard party acting as representatives of the proletariat and its interests. According to Lenin's April Theses, the goal of the revolution and vanguard party is not the introduction of socialism, which could only be established on a worldwide scale, but to bring production and the state under the control of the Soviets of Workers' Deputies. Following the October revolution in Russia, the Bolsheviks consolidated their power and sought to control and direct the social and economic affairs of the state and broader Russian society in order to safeguard against counterrevolutionary insurrection, foreign invasion, and to promote socialist consciousness among the Russian population.
These ideas were adopted by Vladimir Lenin in 1917 just prior to the October Revolution in Russia and published in The State and Revolution, a central text for many Marxists. With the failure of the worldwide revolution, or at least European revolution, envisaged by Lenin and Trotsky, the Civil War, and finally Lenin's death, war measures that were deemed to be temporary, such as forced requisition of food and the lack of democratic control, became permanent and a tool to boost Stalin's power, leading to the emergence of Marxism–Leninism and Stalinism, as well as the notion that socialism can be created and exist in a single state.
Vladimir Lenin argued that as socialism is replaced by communism, the state would "wither away" as strong centralized control progressively reduces as local communities gain more empowerment. As he put succinctly: "So long as the state exists there is no freedom. When there is freedom, there will be no state."
Most theories assume widespread democracy, and some assume workers' democratic participation at every level of economic and state administration, while varying in the degree to which economic planning decisions are delegated to public officials and administrative specialists. States where democracy is lacking, yet the economy is largely in the hands of the state, are termed by orthodox Trotskyist theories as "workers' states" but not socialist states, using the terms "degenerated" or "deformed" workers' states.
States run by Communist parties that adhere to Marxism–Leninism, or some variation thereof, refer to themselves as socialist states. The Soviet Union was the first to proclaim itself a "socialist state" in its 1936 Constitution and a subsequent 1977 Constitution. Another well-known example is the People's Republic of China, which proclaims itself to be a "socialist state" in its 1982 Constitution of the People's Republic of China. In the West, such states are commonly known as "communist states" (though they do not use this term to refer to themselves).
"Socialist state" is widely used by Leninists and Marxist–Leninists in reference to a state under the control of a vanguard party that is organizing the economic, social, and political affairs of said state toward the construction of socialism. This often includes at least the "commanding heights" of the economy to be nationalized, usually operated according to a plan of production, at least in the major production and social spheres. Under the Leninist definition, the socialist state presides over a state capitalist economy structured upon state-directed accumulation of capital, with the goal of building up the country's productive forces and promoting worldwide socialist revolution, with the eventual long-term goal of building a socialist economy.
These "Communist states" often don't claim to have achieved socialism in their countries; rather, they claim to be building and working toward the establishment of socialism (and the development towards communism thereafter) in their countries. For example, the preamble to the Socialist Republic of Vietnam's constitution states that Vietnam only entered a transition stage between capitalism and socialism after the country was re-unified under the Communist party in 1976, and the 1992 Constitution of the Republic of Cuba states that the role of the Communist Party is to "guide the common effort toward the goals and construction of socialism (and the progress toward a communist society)".
The Democratic People's Republic of Korea (North Korea) used to be a Marxist–Leninist state. In 1972, the country adopted a new constitution, which changed the official state ideology to "Juche", which is held to be a distinct Korean re-interpretation of the former ideology. Similarly in Laos, direct references to communism are not included in its founding documents, though it gives direct power to the governing ruling party.
The preamble to the 1976 constitution of Portugal states that the Portuguese state has as one of its goals opening "the way to socialist society".
India, Algeria, Congo Brazaville, Sri Lanka, have directly used the term "socialist" in their official constitution and name, respectively.
In these cases, the intended meaning of "socialism" can vary widely, and sometimes the constitutional references to socialism are left over from a previous period in the country's history. In the case of many Middle-Eastern states, "socialism" was often used in reference to an Arab-socialist/nationalist philosophy adopted by specific regimes, such as that of Gamal Abdel Nasser and that of the various Ba'ath Parties.
Examples of countries directly using the word "socialist" in their names include the Democratic Socialist Republic of Sri Lanka, and the Socialist Republic of Vietnam, while a number of countries make references to socialism in their constitutions but not in their names. These include India and Portugal. In the constitutions of Hungary, Poland, and Croatia, direct condemnation is made to the respective, past socialist regimes. The autonomous region of Rojava, which operates under the principles of democratic confederalism, has been described as a socialist state. In addition, countries like Spain, Belarus, Colombia, and Russia use the varied term 'Social' state, leaving a more ambiguous meaning.
In the post-war period, when nationalisation of large industries was relatively widespread, it was not uncommon for commentators to describe some European countries as "socialist states" seeking to move their countries toward a socialist economy.
In 1956, for example, leading British Labour Party politician and author Anthony Crosland claimed that capitalism had been abolished in Britain, although others—such as Welshman Aneurin Bevan, Minister of Health in the first post-war Labour government—disputed the claim that Britain was a socialist state. For Crosland and others who supported his views, Britain was a socialist state. For Bevan, Britain had a socialist National Health Service which stood in opposition to the hedonism of Britain's capitalist society. He stated:
The National Health service and the Welfare State have come to be used as interchangeable terms, and in the mouths of some people as terms of reproach. Why this is so it is not difficult to understand, if you view everything from the angle of a strictly individualistic competitive society. A free health service is pure Socialism and as such it is opposed to the hedonism of capitalist society.— Aneurin Bevan, In Place of Fear, p. 106
When the Socialist Party was in power in France in the post-war period, some commentators claimed that France was a socialist country, although, as in the rest of Europe, the laws of capitalism still operated fully and private enterprises dominated the economy. In the 1980s, the Mitterrand government aimed to expand dirigisme and scheduled to nationalize all banks but this attempt faced opposition of the European Economic Community. Now applied to nordic countries with the Nordic model.
Reformist socialists, exemplified by Eduard Bernstein, take the view that a socialist state will evolve out of political reforms won by the struggle of the socialists. "The socialist movement is everything to me while what people commonly call the goal of Socialism is nothing." These views are considered a "revision" of Marxist thought.
Revolutionary Marxists, following Marx, take the view that the working class grows stronger through its battle for reforms (such as, in Marx's time, the ten-hours bill):
"Now and then the workers are victorious, but only for a time. The real fruit of their battles lies, not in the immediate result, but in the ever expanding union of the workers... it ever rises up again, stronger, firmer, mightier. It compels legislative recognition of particular interests of the workers, by taking advantage of the divisions among the bourgeoisie itself. Thus, the ten-hours’ bill in England was carried."— Marx and Engels, Manifesto of the Communist Party, Chapter I. Bourgeois and Proletarians
Nevertheless, according to the orthodox Marxist conception, these battles of the workers eventually reach a point at which a revolutionary movement arises. A revolutionary movement is required, in the view of Marxists, to sweep away the capitalist state, which must be smashed, so as to begin to construct a socialist society:
"In depicting the most general phases of the development of the proletariat, we traced the more or less veiled civil war, raging within existing society, up to the point where that war breaks out into open revolution, and where the violent overthrow of the bourgeoisie lays the foundation for the sway of the proletariat."— Marx and Engels, Manifesto of the Communist Party, Chapter I. Bourgeois and Proletarians
In this view, only through revolution can a socialist state be established.
A variety of non–state socialist positions—such as social anarchism, libertarian socialism, and council communism—reject the concept of a "socialist state" altogether, believing that the modern state is a byproduct of capitalism and cannot be used for the establishment of a socialist system. They reason that a "socialist state" is antithetical to socialism, and that socialism will emerge spontaneously from the grassroots level in an evolutionary manner, developing its own unique political and economic institutions for a highly organized stateless society. Anarcho-communists likewise reject the concept of a "socialist state" for being antithetical to socialism, but they believe that socialism—and, thus, communism—can only be established through revolution.
Within the socialist movement, a number of criticisms are maintained towards the use of the term "socialist states" in relation to countries such as China and previously of Soviet Union and Eastern and Central European states before what some term the 'collapse of Stalinism' in 1989. Democratic socialists, left communists, anarchists, and some Trotskyists claim that the so-called "socialist states" or "people's states" actually presided over state capitalist economies and thus cannot be called "socialist".
Other Trotskyists, while agreeing that these states could not be described as socialist, deny that they were state capitalist. They support Trotsky's analysis of (pre-restoration) Soviet Union as a workers' state that had degenerated into a "monstrous" bureaucratic dictatorship which rested on a largely nationalized industry run according to a plan of production, and claimed that the former "Stalinist" states of Central and Eastern Europe were deformed workers' states based on the same relations of production as the Soviet Union.
Certain other countries simply use the self-defining term 'Social' state in their founding documents open to interpretation.
Contrary to Western usage, these countries describe themselves as ‘Socialist’ (not ‘Communist’). The second stage (Marx’s ‘higher phase’), or ‘Communism’ is to be marked by an age of plenty, distribution according to needs (not work), the absence of money and the market mechanism, the disappearance of the last vestiges of capitalism and the ultimate ‘whithering away of the state.
Among Western journalists the term ‘Communist’ came to refer exclusively to regimes and movements associated with the Communist International and its offspring: regimes which insisted that they were not communist but socialist, and movements which were barely communist in any sense at all.
Ironically, the ideological father of communism, Karl Marx, claimed that communism entailed the withering away of the state. The dictatorship of the proletariat was to be a strictly temporary phenomenon. Well aware of this, the Soviet Communists never claimed to have achieved communism, always labeling their own system socialist rather than communist and viewing their system as in transition to communism.
But there are still others (concepts and institutions) which by virtue of their nature cannot stand transplantation and always carry the flavor of a particular institutional framework. It is extremely dangerous, in fact it amounts to a distortion of historical description, to use them beyond the social world or culture whose denizens they are. Now ownership or property – also, so I believe, taxation – are such denizens of the world of commercial society, exactly as knights and fiefs are denizens of the feudal world. But so is the state (a denizen of commercial society).
In 1816, he declares that politics is the science of production, and foretells the complete absorption of politics by economics. The knowledge that economic conditions are the basis of political institutions appears here only in embryo. Yet what is here already very plainly expressed is the idea of the future conversion of political rule over men into an administration of things and a direction of processes of production.