Most political philosophers at some point refer to something called "society". "We owe a debt to society." "The basic structure of a society must be justifiable to all people in that society on terms they can reasonable accept." "We should provide a universal basic income to all people in our society." "A society is just only if the 'distribution' of income matches this particular pattern I concocted last night.' "Our society is racist." That kind of thing.
Philosophers almost always uncritically assume that "society" is coextensive with some nation-state or other.
On its face, this seems clearly false.
For instance, consider the Ralwsian-style arguments for prioritizing co-nationals in welfare payments, or for holding that principles of distributive justice hold for people inside nation-states but not between them: Rawls would say that we have special obligations to those within the same society, because we are involved in a web of cooperation from which we as individuals derive great benefit.
Here, the argument is that your own personal welfare depends in large part on your membership in and belonging to a particular society. You depend upon various background institutions, past rates of capital accumulation, and so on. In virtue of receiving such benefits, you owe more to fellow participants who helped create and sustain the social conditions that make you so well off.
However, there’s no clear way in which the “society” in question here just so happens to be co-extensive with the modern nation-state. Each of us is connected to billions of others in complex webs of cooperation, with some people close and others distant, with some strands thick and others thin, all organized by various overlapping formal and informal institutions, most of which regulate parts of the web but not the whole thing. Each of our webs is different and different parts of our individual webs are governed by different institutions. Your web does not match the borders of your nation-state, and indeed, you are more highly connected to, dependent on, and aided by many people outside your borders than many/most people inside.
Similarly, suppose Rawls says, "We owe more to co-nationals because we have to justify the rules of the game to them. The institutions of our society won’t be legitimate unless each member has a sufficient stake in those rules, and sufficiently benefits from them, that it’s reasonable to demand they play along by those rules.”
But, again, there’s no plausible interpretation of “society” which equates it with any modern-nation state. You are part of a web of cooperation and influence, with different institutions regulating and influencing different parts of your web. Even the institutions that directly regulate you are not co-extensive with your nation-state. They involve more both more local and more international laws, rules, customs, and norms. Your web of cooperation overlaps with but is different from mine.
Rawls has no response to this objection, because he explicitly imagines away this complexity. In A Theory of Justice, for the ease of constructing his theory, he asks us to imagine an isolated autarkical nation-state, which people enter only by birth and leave only by death, in which all norms, customs, and laws are more or less uniform across the entire state. In Rawls’s imaginary example, he stipulates that society is equivalent to all the members of a state and we are all indeed subject to the same basic structure. But this has little to do with the real world. In the real world, nation-states do not have a uniform basic structure and there is no “society” co-extensive with the nation-state.
It's not as though the real world is simply a complicated departure from Rawls's thought experiment or model. Rather, Rawls's thought experiment fails to model or capture the important aspects of real-life social interaction. The reality is--a reality which any serious political philosophy must acknowledge--that we are each in complex webs of interaction and influence, each with slightly different webs, with some strands thicker than others, and with the webs not matching the boundaries of our modern nation-states.
If you're reading a book or article on political or social philosophy which makes this mistake, throw it in the trash can. It's trying to analyze or solve a fake problem while ignoring the real problem.
Society ≠ all the people subject to a particular national government.