There's something I notice about typical blog-comments advocates of "Gay Rights", Global Warming legislation and PETA members: They typically all so fucking frantic and emotional.
In the Gay Rights case, merely saying you're against gay marriage or that you think homosexual acts are immoral too often quickly turns into screams about phobia and how you're the reason homosexually inclined teens commit suicide and how you're personally responsible for some "good ol' boy" (it's always the southerners) tying someone to the back of his truck.
In the Global Warming case it's this frantic declaration that the world is doomed unless we take action *this year* and the only reason people don't is because they're greedy and they know the world is doomed and don't care and... etc. Incidentally, this frantic insistence that we have to act *right now or we're doomed* has been going on for years. You'd think at this point anyone who really believed in the direst AGW forecasts would say "Too late for preventive measures. We should be preparing for the warming itself." Oddly, never comes up.
And of course the PETA case is simply one melodramatic, emotional display after another. People whose imaginations are askew and now they're very convinced that their housecat "really hopes they pass their biology test" because clearly the cat can tell this is important to them and so on.
I think the common thread winding up all three is this: Frantic emotional investment. There is no stepping back and evaluating the questions reasonably, because a reasonable evaluation is the exact opposite of the point. It's all about the drama, the story-book nature of the evils being committed, the good guys and the bad guys and the unsung heroes and so on. To actually pull back and discuss the topic rationally is almost seen as insulting - why, that would sap the emotional high of CARING so damn much. People love their drama, after all - and if they need melodrama to get it, that's just the price to pay.
There's a place for emotion, of course. But when it's the driving force of thought, when too much of your argument comes down to "I just feel so STRONGLY about this!", it's time for either a reality check.