Bradbury stated that "Fahrenheit 451" is not about censorship, but Captain Beatty cites censorship as one of the main reasons books ended up banned.
This is a very topical subject for the world of today. On the one hand, globalisation has resulted in an unprecedented level of information and an unprecedented level of access to that same information. Yet at the same time there are more options to subvert, manipulate or completely distort that information through the same medium that has given us that information. Here is a disturbing question for you - how do we know, with all the many different news channels and newspapers that there are in the world, that we are actually hearing the news as opposed to someone's take on it? Who controls those networks of information and for what reason?
Obviously, as others have commented, there is a necessary level of censorship - we would not be happy with our children being exposed to sights they should not see on the TV for example, but who draws that line, and where do they do it?
It is a slippery slope from censorship to “shameless destruction of information.” There are of course certain times when censorship is appropriate; some things that are fit for adult audiences should not be viewed by children. Nevertheless, the definition of “appropriate” varies depending on one’s religious, moral, ethical, and cultural background. In a democracy, there is a balance of power to prevent any one entity from hijacking the right to censor material. The United States has the executive, legislative, and judicial branches of government, along with the Fourth Estate, a free press. The tension among these entities serves to help define the limits of censorship. Frequent turnover of positions in the government also help to temper any individual or party’s tendencies.
Society accepts censorship if it is generally agreed that the reason is truly valid. For instance, no reasonable person would advocate the publishing of information that would lead their country to military destruction or defeat. Beyond that, censorship becomes impossible to defend because it limits the flow of information according to someone's particular agenda. A censor denies the individual's right to know, to think, and to judge. I am reminded of Inherit the Wind and the efforts of some to prevent the reading of Darwin's work. In that play Rachel says that some ideas will prevail, while the weak ones will wither away. Censorship derails the process of separating strong ideas from weak ones, the search for truth and understanding.
Ray Bradbury did in fact write Fahrenheit 451 about his concerns with censorship and conformity, published during the hysteria of the McCarthy Era.
There is no appropriate place to draw the line on censorship. And as far as the destruction of information, such as in the novel, where the burning of books is seen as a duty to the state, it invokes a frightening image where a government would determine what the citizen would be allowed to read.
In Fahrenheit 451, reading and learning have been banned because people supposedly lost interest in pursuing education, all institutions of learning have been closed. That is why when Montag meets Faber, a displaced English Professor, he finds his presence so inspiring. The death of reading, the banning of books, censorship have no place in a free society.
Learning is essential to the survival of the species, learning and education are the cornerstones of the future. In Fahrenheit 451, there is no future except one that continues to deprive the people of the basic elements of life. You will note, that Montag becomes part of the resistance movement, the keeper of books and expects to emerge victorious one day.
The themes of "Fahrenheit 451," deal with isolation, loneliness, apathy, and change. The Government has taken complete control of Montag's society. Censorship is part of that control. They do not censor writing, they have completely banned all books and all writing from the society. At one point Beatty says that if you don't let people read then there isn't anything for them to argue, think, or complain about. They will simply do as they are told. Montag is one of the few characters we meet in the novel who truly questions what is going on in his society. Everyone tunes into the wall screens and just does as they are told. Censorship is never right as far as I am concerned.
"Censorship supervision and control of the information and ideas that are circulated among the people within a society. In modern times, censorship refers to the examination of books, periodicals, plays, films, television and radio programs, news reports, and other communication media for the purpose of altering or suppressing parts thought to be objectionable or offensive."
The firemen in Montag's society went beyond this type of censorship. They eliminated the written word completely by the willful destruction of information and destroyed work that has been created for mass consumption. If a government or ruling body destroys something that gives people the freedome to look at that information and draw their own conclusions then they are destroying work.
The novel is about control of society and how different characters responded to that control. The novel is about the change that Montag faces because of moral decisions he must make.
This is one of the fundamental issues raised out of Bradbury's work. It seems that he is articulating a vision of a world where government believes that perfection, some idyll of a world, is possible. In that name, in that purpose, and in accordance with that vision, there is a desire to destroy books and literature. While the book might not be about censorship, according to Bradbury, he is forcing this issue to be debated and discussed. I think that you want to answer it in two ways. The first way would be how the book addresses it in terms of the situations presented and the structures of power offered. The second way would be in how you personally feel about it. In terms of the former, I think the book raises some very intense issues about what happens when government or a social body begins to be the agent that determines "what is appropriate." We see this idea in Orwell's "1984" and the "thought police." It is a similar, if not same, principle here. Does government or any external body have a natural or fundamental right to engage in the destruction of information that it deems as "inappropriate" for its people? Where is that line? If citizens have freedom, then don't that have a natural or fundamental right to be able to determine for themselves what they deem as appropriate and what isn't appropriate? Sometimes, governments and social orders have a vision of how to appropriate the world in accordance to their own senses of subjectivity. In this name, they step into the domain of curtailing and limiting individual freedom. Perhaps Bradbury is giving a vision of what happens when this individual freedom is limited. It becomes scary, indeed.
Taking the second part of your question, I think that the line that is drawn is something that Bradbury would say is up to the individual. His vision of Captain Beatty burning books is the result of when this discretion is ignored. Individuals must be able to determine for themselves where this line is because in any democratic setting, when the social or governmental order makes this demarcation, bad things cannot be far behind.