Civil Disobedience opens by accepting a libertarian motto: 'That government is best which governs least,' and pushing it to its logical limit. Thoreau does not call for anarchy, but he insists that government is at best an expedient, and that most governments allow themselves to be abused. The immediate context is the United States in 1848: a nation waging what Thoreau regards as an unjust war against Mexico, and one that has built its prosperity partly on chattel slavery.
The essay's philosophical core is the claim that the majority has no right to decide questions of conscience. Majority rule rests on physical strength, not on justice. A government that asks a citizen to act as an agent of injustice, whether as a soldier in an unjust war or as a taxpayer funding one, has lost the right to that citizen's compliance. The duty, Thoreau argues, is to be a man first and a subject afterward.
From argument, the essay turns to autobiography. Thoreau spent one night in Concord jail for refusing to pay the poll tax. His account of that night is sharp and ironic: the walls seemed a great waste of stone, since the state could confine his body but not his thoughts or his moral independence. He was released the next morning, after someone had paid the tax on his behalf without his consent, and he noticed that a change had come over his view of his neighbors and his town. They were more concerned with comfort than with justice.
The practical proposal is peaceable withdrawal. Thoreau does not call for violence but for the refusal of allegiance: stop paying taxes, resign from institutions that enforce injustice, and accept the jail that follows. If a thousand, or even one honest person, were to be locked up for refusing to hold slaves, it would force the question in a way that petitions never could. A minority is powerless when it conforms; it is irresistible when it refuses.
The essay ends with a vision of a higher state that has not yet appeared anywhere. Such a state would recognize the individual as a higher and independent power from which all its authority is derived. Until then, Thoreau offers no comfortable middle ground: the just man under an unjust government belongs in prison, on the only ground the state has provided for those who are against it.