Communitarianism emerged in the 1980s as a critical response to Rawlsian liberalism. Its charge is that liberal political philosophy rests on an implausibly abstract conception of the self, detached from the communities, attachments and moral traditions that in fact constitute human identity, and that a politics built on that abstraction erodes the very goods it depends on.
Its founding texts arrived within a few years of each other. MacIntyre's After Virtue (1981) argued that modern moral discourse is the wreckage of an older Aristotelian framework, retaining the vocabulary of virtue while having lost the shared account of human purpose that gave it sense. Sandel's Liberalism and the Limits of Justice (1982) pressed directly on Rawls's unencumbered self, arguing that people do not choose their deepest commitments from behind a veil but discover themselves already situated within them. Walzer's Spheres of Justice (1983) argued that distributive principles are internal to the shared meanings of particular goods in particular societies. Taylor traced how the modern self came to seem natural.
Most of these figures rejected the label, and the disagreements among them are large. MacIntyre's Thomism, Taylor's Catholic phenomenology, Walzer's democratic socialism and Sandel's civic republicanism are not one position. What unites them is a claim about method and not a political program, which is why communitarian arguments have been taken up by both left and right.
The standing objection is that the tradition has no account of which community's standards should govern, and that grounding justice in shared meanings gives the majority a veto over the dissenter and the outsider. A settled tradition can be settled in favor of some at the expense of others. Communitarians generally answer that liberalism's neutrality is itself a substantive tradition unaware of its own particularity, which sharpens the question without resolving it.