Under hard line statism, such as centrally planned socialism and absolute monarchy, everyone belongs to society – there are no individuals, no privacy, no private property, etc. Thus, for instance, in Marxism all vital property is collectively owned and administered by the state/government. Since the most vital of all property is human productive labor, everyone's productive labor belongs to the society and must be administered by the state/government. (The late Robert Heilbroner, the author of The Worldly Philosophers, a book that for many decades was required reading for many incoming college freshmen, is one Western Marxist who acknowledged this in his book Marxism: For and Against.) It follows from it that those who tried to escape from East Germany were officially taken to be stealing the state's property, taking it to the West, and this had to be opposed and prevented. Shooting those who tried to scale the Berlin Wall amounted to shooting thieves!
Given Marx's labor theory of value, it follows that a socialist system involves public ownership of human labor. And that pretty much implies the public ownership of human beings.
Yet it isn't only Marxists who are philosophically committed to the idea that people belong to society. Charles Taylor, the Canadian communitarian philosopher from McGill University holds that people belong to their communities. Just what counts as one's community is difficult to be sure about – in one sense everyone belongs to innumerable communities, such as families, neighborhoods, professions, political parties, drivers of Volkswagens, joggers, twenty-somethings and on and on. None of these have a claim on any human beings beyond being associated with many, many others who share in a common purpose or in some common activities. All are associations that are voluntarily entered into or continued and are easily ended.
The kind of belonging Taylor and others have in mind is more forceful, coercive, the sort one cannot unilaterally end. Like being from a certain country or being a member of an age group or, again, having a given ethnicity. These communities are part of what some would call one's identity and by the communitarian account have a claim on one's life, labor, resources and such. One might even say that one belongs in such cases as one might belong to a proprietor. It calls to mind slavery or at least serfdom. It comes, as communitarians such as Harvard University's famous Professor Michael J. Sandel (the host of the program Justice on PBS TV and author of a book by that title) holds, with unchosen obligations, duties that government may enforce, like doing military service to the country or paying taxes.
It is this element of communitarianism that qualifies it as mainly a statist political position and indeed there are some conservative champions of the doctrine as well. Even the avowed individualist conservative, the late William F. Buckley, Jr., advocated national service for teens! In either case it is the source of hostility toward individualism, be that the mild one according to which everyone has the basic right to choose on his or her own initiative what kind of life he or she will live, or the more radical type which holds that we are all self-sufficient, independent persons. The extreme version of the communitarian idea is that we all belong to society or humanity or humankind. And here the "belong" is meant in the proprietary sense.
The most forceful statement of this collectivist view was put forth by Auguste Comte, the French "father of sociology" in the following passage:
"Everything we have belongs then to Humanity…Positivism never admits anything but duties, of all to all. For its social point of view cannot tolerate the notion of right, constantly based on individualism. We are born loaded with obligations of every kind, to our predecessors, to our successors, to our contemporaries. Later they only grow or accumulate before we can return any service. On what human foundation then could rest the idea of right, which in reason should imply some previous efficiency? Whatever may be our efforts, the longest life well employed will never enable us to pay back but an imperceptible part of what we have received. And yet it would only be after a complete return that we should be justly authorized to require reciprocity for the new services. All human rights then are as absurd as they are immoral. This ["to live for others"], the definitive formula of human morality, gives a direct sanction exclusively to our instincts of benevolence, the common source of happiness and duty. [Man must serve] Humanity, whose we are entirely." Auguste Comte, The Catechism of Positive Religion (Clifton, NJ: Augustus M. Kelley Publ., 1973), pp. 212-30. (It was Comte who coined the term "altruism"!)
What was unique in the American political tradition, which drew on John Locke instead of the likes of Comte, is the rejection of this reactionary idea! That is what made America exceptional, albeit, sadly, incompletely so.