‘Canonicity’: the Book or the Reader?

[The Saucepan Man]

If the "freedom of the reader is boundless" then does this mean that there is no such thing as a wrong or incorrect interpretation?

Of course there isn't, as far as an individual's personal thoughts are concerned. The reader is free to think what he or she chooses. Any other analysis would come close to conjuring up the "thought police" of 1984.

But, as I said, where the individual interacts with others (for example by entering a discussion or publishing his or her views), then that individual's freedom may be circumscribed by the circumstances of the interaction. Such circumscription might be legal, by application of laws such as those relating to defamation or race relations (for example, it recently became a criminal offence in the UK to incite others to racial hatred). Or it might be by means of censorship, editorial discretion, self-selection or even simply social pressure.

what about people -- who do exist, sadly -- who interpret the novel as supporting white supremacy?

I am unfortunately aware of the "white supremacy" issue (there is a thread concerning a site devoted to this view somewhere around here). To answer you, these people are free to think what they want and, subject to the legal issues that I mention above, they are free to disseminate their views to others. Indeed, it appears that they set the agenda on their own site and censor any posts which do not accord with their views (as Findegil said, they don't want to have to deal with dissenting opinions). Thus, the freedom of those who seek to point out the fallacies in the white supremacists' interpretation is, in these circumstances, circumscribed by censorship/editorial discretion.

If, on the other hand, these people were to try to make the "white supremacist" argument on this forum, I would expect a flurry of well-argued points refuting their position by reference to Tolkien's writings (both published and unpublished). They choose not to do so because they don't want to hold themselves up to ridicule in this way (self-selection/social pressure). In other situations, the dissemination of their views may well be restricted by means of censorship or editorial discretion. So, in effect their freedom to argue for their interpretation will also be circumscribed in certain circumstances.

What if I want to interpret the novel as an allegory about the rise of Communism (Sauron) in the early 20th century and the reprisal against that by bourgeouis, middle-class humanism (hobbits) and the remnants of a European aristrocratic society (Gondor)?

Again, you are free to think this. And you are free to make your interpretation known to others. You would have to accept that Tolkien did not intend this allegory, since he made clear that his novels were not intentionally allegorical. But, as a personal interpretation, it may still be of interest and/or value to others.