Here is a brief quote:
Denialism: the employment of rhetorical tactics to give the appearance of argument or legitimate debate, when in actuality there is none. These false arguments are used when one has few or no facts to support one's viewpoint against a scientific consensus or against overwhelming evidence to the contrary. They are effective in distracting from actual useful debate using emotionally appealing, but ultimately empty and illogical assertions.
I think of Denialism as a strategy but also as a disease. Maybe a better name for it would be Inhofism, Hannity's Syndrome or Malkinosis. Whatever the name, I get extremely frustrated whenever I see an Allegedly Serious News Person discuss Global Warming (or torture, or health care reform, or labor rights, or regulation, or any other serious issue) with a Denier. The frustration comes from the ASNP seeming to challenge the Denier, but actually giving them undeserved credibility.
As those of us who have raised children remember, the problem with arguing with a two-year old is that, sooner or later, you may start arguing LIKE a two-year old. The same problem crops up when arguing with a Denier. The challenger usually attacks the Denier's false facts or defends his own real ones. The first and most serious flaw in that approach is that it raises the Denier's lies to the level of "opposing facts". The second is that it ignores Sun Tzu's dictum: "...the highest form of generalship is to balk the enemy's plans..."
The rhetorical tricks used by Deniers are hard for most listeners to detect, and require more mental energy than most people are willing to expend. That's why I keep hoping that a Chris Matthews, or a Campbell Brown, or a Bob Schieffer, or a David Gregory will start regularly dissecting the false logic in what Deniers say to them. The fact that they do it occassionally, and effectively, proves they can do it.
