Numerous scholars have grappled with the problem of censorship, and historically, the arguments against it have fallen into several different categories. First, some have argued that open and free discussion is crucial for the discovery of truth, or from a more pragmatic standpoint, the best possible conclusion. This argument, perhaps first expressed by John Milton in Areopagitica, was echoed by John Stuart Mill and later Oliver Wendell Holmes. By this way of thinking, society as a whole is hurt by censorship.
Others, including Mill, simply argue that democracy is based on debate, and if the people are to make political decisions, then they must be free to discuss their options without certain ideas being censored. Mill argued in On Liberty:
If all mankind minus one were of one opinion, and only one person were of contrary opinion, mankind would be no more justified in silencing that one person, than he, if he had the power, would be justified in silencing mankind.
Still others have asserted that free speech and expression is a natural right, to be protected rather than usurped by government. They interpret the First Amendment broadly as the instrument by which protection is provided.
These arguments have historically clashed with what some have deemed to be the public interest, and some of the most famous censorship cases that have reached the United States Supreme Court have involved censorship not of speech but of art or literature that has been deemed obscene. Here, the problem with censorship is that it is difficult to ascertain exactly what, exactly is obscene, and whether the public interest in free expression and speech is outweighed by its interest in maintaining these standards through censorship.
While the material in these cases has not typically been political in nature, some have made a "slippery slope" argument in demonstrating another problem with censorship in any form. Censoring one type of literature, thought, or art can be used as precedent to censor another.