Thoreau asserts that because governments are typically more harmful than helpful, they therefore cannot be justified. Democracy is no cure for this, as majorities simply by virtue of being majorities do not also gain the virtues of wisdom and justice. The judgment of an individual's conscience is not necessarily inferior to the decisions of a political body or majority, and so "[i]t is not desirable to cultivate a respect for the law, so much as for the right. The only obligation which I have a right to assume is to do at any time what I think right.... Law never made men a whit more just; and, by means of their respect for it, even the well-disposed are daily made the agents of injustice." He adds, "I cannot for an instant recognize as my government [that] which is the slave's government also."
The government, according to Thoreau, is not just a little corrupt or unjust in the course of doing its otherwise-important work, but in fact the government is primarily an agent of corruption and injustice. Because of this, it is "not too soon for honest men to rebel and revolutionize."
Political philosophers have counseled caution about revolution because the upheaval of revolution typically causes a lot of expense and suffering. Thoreau contends that such a cost/benefit analysis is inappropriate when the government is actively facilitating an injustice as extreme as slavery. Such a fundamental immorality justifies any difficulty or expense to bring to an end. "This people must cease to hold slaves, and to make war on Mexico, though it cost them their existence as a people."
Thoreau tells his audience that they cannot blame this problem solely on pro-slavery Southern politicians, but must put the blame on those in, for instance, Massachusetts, "who are more interested in commerce and agriculture than they are in humanity, and are not prepared to do justice to the slave and to Mexico, cost what it may... There are thousands who are in opinion opposed to slavery and to the war, who yet in effect do nothing to put an end to them." (See also: Thoreau's Slavery in Massachusetts which also advances this argument.)
He exhorts people not to just wait passively for an opportunity to vote for justice, because voting for justice is as ineffective as wishing for justice; what you need to do is to actually be just. This is not to say that you have an obligation to devote your life to fighting for justice, but you do have an obligation not to commit injustice and not to give injustice your practical support.
Paying taxes is one way in which otherwise well-meaning people collaborate in injustice. People who proclaim that the war in Mexico is wrong and that it is wrong to enforce slavery contradict themselves if they fund both things by paying taxes. Thoreau points out that the same people who applaud soldiers for refusing to fight an unjust war are not themselves willing to refuse to fund the government that started the war.
In a constitutional republic like the United States, people often think that the proper response to an unjust law is to try to use the political process to change the law, but to obey and respect the law until it is changed. But if the law is itself clearly unjust, and the lawmaking process is not designed to quickly obliterate such unjust laws, then Thoreau says the law deserves no respect and it should be broken. In the case of the United States, the Constitution itself enshrines the institution of slavery, and therefore falls under this condemnation. Abolitionists, in Thoreau's opinion, should completely withdraw their support of the government and stop paying taxes, even if this means courting imprisonment.
Under a government which imprisons any unjustly, the true place for a just man is also a prison.… where the State places those who are not with her, but against her,– the only house in a slave State in which a free man can abide with honor.… Cast your whole vote, not a strip of paper merely, but your whole influence. A minority is powerless while it conforms to the majority; it is not even a minority then; but it is irresistible when it clogs by its whole weight. If the alternative is to keep all just men in prison, or give up war and slavery, the State will not hesitate which to choose. If a thousand men were not to pay their tax bills this year, that would not be a violent and bloody measure, as it would be to pay them, and enable the State to commit violence and shed innocent blood. This is, in fact, the definition of a peaceable revolution, if any such is possible.
Because the government will retaliate, Thoreau says he prefers living simply because he therefore has less to lose. "I can afford to refuse allegiance to Massachusetts…. It costs me less in every sense to incur the penalty of disobedience to the State than it would to obey. I should feel as if I were worth less in that case."
He was briefly imprisoned for refusing to pay the poll tax, but even in jail felt freer than the people outside. He considered it an interesting experience and came out of it with a new perspective on his relationship to the government and its citizens. (He was released the next day when "someone interfered, and paid that tax.")
Thoreau said he was willing to pay the highway tax, which went to pay for something of benefit to his neighbors, but that he was opposed to taxes that went to support the government itself—even if he could not tell if his particular contribution would eventually be spent on an unjust project or a beneficial one. "I simply wish to refuse allegiance to the State, to withdraw and stand aloof from it effectually."
Because government is man-made, not an element of nature or an act of God, Thoreau hoped that its makers could be reasoned with. As governments go, he felt, the U.S. government, with all its faults, was not the worst and even had some admirable qualities. But he felt we could and should insist on better. "The progress from an absolute to a limited monarchy, from a limited monarchy to a democracy, is a progress toward a true respect for the individual.… Is a democracy, such as we know it, the last improvement possible in government? Is it not possible to take a step further towards recognizing and organizing the rights of man? There will never be a really free and enlightened State until the State comes to recognize the individual as a higher and independent power, from which all its own power and authority are derived, and treats him accordingly."
An aphorism sometimes attributed to either Thomas Jefferson or Thomas Paine, "That government is best which governs least...", was actually found in Thoreau's Civil Disobedience. Thoreau was paraphrasing the motto of The United States Magazine and Democratic Review: "The best government is that which governs least." Thoreau expanded it significantly:
I heartily accept the motto,—“That government is best which governs least;” and I should like to see it acted up to more rapidly and systematically. Carried out, it finally amounts to this, which I also believe,—“That government is best which governs not at all;” and when men are prepared for it, that will be the kind of government which they will have. Government is at best but an expedient; but most governments are usually, and all governments are sometimes, inexpedient.—Thoreau, Civil Disobedience