“"But," it will be asked of the Anarchists at this point in the argument, "what shall be done with those individuals who undoubtedly will persist in violating the social law by invading their neighbors?" The Anarchists answer that the abolition of the State will leave in existence a defensive association, resting no longer on a compulsory but on a voluntary basis, which will restrain invaders by any means that may prove necessary.”

Individual Liberty (1926), Liberty and Politics

Individual Liberty (1926), Liberty and Politics

Chap. 3 : The Chronology of Cooperation
Proposition 7.
The Evolution of Cooperation (1984; 2006)

Anarchism : A History of Libertarian Ideas and Movements (1962)
Context: Like such titles as Christian and Quaker, "anarchist" was in the end proudly adopted by one of those against whom it had been used in condemnation. In 1840, Pierre-Joseph Proudhon, that stormy, argumentative individualist who prided himself on being a man of paradox and a provoker of contradiction, published the work that established him as a pioneer libertarian thinker. It was What Is Property?, in which he gave his own question the celebrated answer: "Property is theft." In the same book he became the first man willingly to claim the title of anarchist.
Undoubtedly Proudhon did this partly in defiance, and partly in order to exploit the word's paradoxical qualities. He had recognized the ambiguity of the Greek anarchos, and had gone back to it for that very reason — to emphasize that the criticism of authority on which he was about to embark need not necessarily imply an advocacy of disorder. The passages in which he introduces "anarchist" and "anarchy" are historically important enough to merit quotation, since they not merely show these words being used for the first time in a socially positive sense, but also contain in germ the justification by natural law which anarchists have in general applied to their arguments for a non-authoritarian society.

Anarchism And Other Impediments To Anarchy (1985)

The Moon Is a Harsh Mistress (1966)
Context: A rational anarchist believes that concepts, such as "state" and "society" and "government" have no existence save as physically exemplified in the acts of self-responsible individuals. He believes that it is impossible to shift blame, share blame, distribute blame... as blame, guilt, responsibility are matters taking place inside human beings singly and nowhere else. But being rational, he knows that not all individuals hold his evaluations, so he tries to live perfectly in an imperfect world... aware that his efforts will be less than perfect yet undismayed by self-knowledge of self-failure.

Man and Socialism in Cuba (1965)

Letter, while US Congressman, to his friend and law-partner William H. Herndon, opposing the Mexican-American War (15 February 1848)
1840s
Context: Allow the President to invade a neighboring nation, whenever he shall deem it necessary to repel an invasion, and you allow him to do so, whenever he may choose to say he deems it necessary for such purpose, and you allow him to make war at pleasure. Study to see if you can fix any limit to his power in this respect, after having given him so much as you propose. If, to-day, he should choose to say he thinks it necessary to invade Canada, to prevent the British from invading us, how could you stop him? You may say to him, "I see no probability of the British invading us" but he will say to you, "Be silent; I see it, if you don't."
The provision of the Constitution giving the war making power to Congress was dictated, as I understand it, by the following reasons. Kings had always been involving and impoverishing their people in wars, pretending generally, if not always, that the good of the people was the object. This, our Convention understood to be the most oppressive of all Kingly oppressions; and they resolved to so frame the Constitution that no one man should hold the power of bringing this oppression upon us. But your view destroys the whole matter, and places our President where kings have always stood.

Source: Lectures on The Industrial Revolution in England (1884), p. 219. "Are Radicals Socialists?",
Context: The Radical creed, as I understand it, is this: We have not abandoned our old belief in liberty, justice, and Self-help, but we say that under certain conditions the people cannot help themselves, and that then they should be helped by the State representing directly the whole people. In giving this State help, we make three conditions: first, the matter must be one of primary social importance; next, it must be proved to be practicable; thirdly, the State interference must not diminish self-reliance. Even if the chance should arise of removing a great social evil, nothing must be done to weaken those habits of individual self-reliance and voluntary association which have built up the greatness of the English people. But — to take an example of the State doing for a section of the people what they could not do for themselves — I am not aware that the Merchant Shipping Act has diminished the self-reliance of the British sailor. We differ from Tory Socialism in so far as we are in favour, not of paternal, but of fraternal government, and we differ from Continental Socialism because we accept the principle of private property, and repudiate confiscation and violence. With Mazzini, we say the worst feature in Continental Socialism is its materialism. It is this indeed which utterly separates English Radical Socialists from Continental Socialists — our abhorrence and detestation of their materialistic ideal. To a reluctant admission of the necessity for State action, we join a burning belief in duty, and a deep spiritual ideal of life. And we have more than an abstract belief in duty, we do not hesitate to unite the advocacy of social reform with an appeal to the various classes who compose society to perform those duties without which all social reform must be merely delusive.
To the capitalists we appeal to use their wealth, as many of their order already do, as a great national trust, and not for selfish purposes alone. We exhort them to aid in the completion of the work they have well begun, and, having admitted the workmen to political independence, not to shrink from accepting laws and carrying out plans of social reform directed to secure his material independence.
To the workman we appeal by the memory and traditions of his own sufferings and wrongs to be vigilant to avoid the great guilt of inflicting upon his fellow-citizens the injustice from which he has himself escaped.