Thoreau was strongly against the Mexican-American war and slavery. To express his view he refused to pay taxes to the government and was shortly incarcerated for this. In Civil Disobedience Thoreau details why and how he will oppose the government. He supports the saying "That government which is best governs least" but adds "That government which is best governs not at all". He says that people should do more than merely express their views, but should actively pursue change in the government..,"even voting for the right thing is doing nothing for it".
"Let your life be a counter friction to stop the machine". Even if your opinion may be a minority and many disagree with you, you can still become a "majority of one" if you stay true to yourself it doing what is right.
Thoreau believes that becoming wealthy can limit our choices, influence and opportunities because we have become dependent on the system that has given us our wealth. A rich man is "sold to the institution which makes him rich...the more money, the less virtue...The opportunities of living are diminished in proportion as what are called the "means" are increased. The best thing a man can do for his culture is when he is rich is to endeavour to carry out those schemes which he entertained when he was poor".
In A Plea for Captain John Brown Thoreau comments on how people have said that John Brown "threw his life away" by his violent support of the abolitionist movement. Thoreau says that people throw away their lives everyday, yet keep living. At least John Brown got something in return. Thoreau expresses his deep disdain for slavery calling it inhumane and unholy.
Now - here is the great controversy in my mind. Thoreau asks "Is it not possible that an individual may be right and the government wrong? Are laws to be enforced simply because they were made? ..are judges to interpret the law according to the letter, and not the spirit?"
Thoreau's writings make one wonder when we can consider a law unjust. Can we choose to disobey laws we do not agree with? The other essays of Thoreau that I read included Slavery in Massachusetts, Walking, and Life Without Principle.
Thoreau's opposition to unjust laws is an interesting contrast to Socrates (in Crito) where the ancient philosopher feels he must obey all laws, even ones that sentence him to death.