Worth a read
The raw data consisted of the comment sections of various online news
articles. Samples were taken from news articles posted between July 1st
and December 31st, 2011, on four mainstream news websites: ABC (American
Broadcasting Company) News, CNN, the Independent, and the Daily Mail.
This date range was chosen because of the large number of 9/11-related
articles around the time of the tenth anniversary of the attacks, and
these four news sites were selected on the reasoning that an ideal
sample would not be restricted to a single country, journalistic style,
or ideological position, as well as for more practical reasons such as
search capabilities, comment archiving, and unpaid access.
I do have an alternate explanation for this observation:
We also found that hostility was higher in persuasive arguments made by
conventionalists than in those by conspiracists. As 9/11 conspiracism is
by and large a minority viewpoint in the West (WorldPublicOpinion.org, 2008),
this makes sense: conventionalists, rather than focusing on presenting
novel information, instead attempt to enforce conformity to the majority
viewpoint (Latané, 1981).
There's an element of truth in that; keeping people in line lends itself more to denigrating the opposition, whereas converting people requires gentler persuasion. But there's another dynamic as well. In general, Truthers know a great deal more of the minutiae of 9-11 than those debating them. I have been at this for over 7 years now, and I'll freely admit that many if not most Truthers know more about that day than I do (although on the important issues I have them cold). This is probably true for most conspiracy theories for an obvious reason; if you are into a conspiracy theory you are going to spend a lot more time studying up on the event than if you believe in the conventional explanation.
But of course, what happens when a conventionalist without a lot of background knowledge runs up against a conspiracy theorist who can provide a lot of detail? He gets frustrated and angry; he knows he's right, but he cannot provide the evidence to support his opinions and hence tends to lash out. There's an old joke about how lawyers work: When you have the facts on your side, pound the facts. When you have the law on your side, pound the law. When you have neither, pound the table.