The ideal of anarchism is a society in which all individuals can do whatever they choose, except interfere with the ability of other individuals to do what they choose. This ideal is called anarchy, from the Greek anarchia, meaning absence of government.
Anarchists do not suppose that all people are altruistic, or wise, or good, or identical, or perfectible, or any romantic nonsense of that kind. They believe that a society without coercive institutions is feasible, within the repertoire of natural, imperfect, human behaviour.
Anarchists do not “lay down blueprints for the free society”. There are science-fiction stories and other fantasies in which anarchies are imagined, but they are not prescribed. Any society which does not include coercive institutions will meet the anarchist objective.
It seems clear, however, that every conceivable anarchy would need social pressure to dissuade people from acting coercively; and to prevent a person from acting coercively is to limit that person’s choices. Every society imposes limits, and there are those who argue, with the air of having an unanswerable argument, that this makes anarchism impossible.
But anarchy is not perfect freedom. It is only the absence of government, or coercive establishments. To show that perfect freedom is impossible is not to argue against anarchism, but simply to provide an instance of the general truth that nothing is perfect.
Of course, the feasibility of anarchy cannot be certainly proved. “Is anarchy practicable?”, is a hypothetical question, which cannot be answered for certain, unless and until anarchy exists. But the question, “Is anarchy worth striving for?”, is an ethical question, and to this every anarchist will certainly answer yes.