I argue that ridicule is a bad means of communication, whether you want to persuade or just inform. It only makes people angry.
I assumed, for a long time, that satire was a good way to make a point. You know Jonathan Swift's essay "A Modest Proposal", in which he criticizes English treatment of the Irish by advocating absurdly terrible treatment? I was required to write my own satire in the same style in high-school English. So proud was I of the result that I posted it on a web forum. It was received badly, which didn't surprise me too much. What surprised me was that people thought it was in earnest, even though it was written in an obviously humorous tone. I had run afoul of Poe's law: there are people who believe things that are so crazy that one can't assume apparent lunacy is in fact satire.
Poe's law is the most obvious threat to satire as an effective means of communication. If people don't get the joke, they'll definitely miss the point. But even if they do get the joke, the nature of satire makes it unlikely that they'll understand the details of what you, the author of the satire, really believe. The problem is that satire relies on hyperbole. And hyperbole precludes expressing the finer details of your own views. You can't readily acknowledge ways in which you agree with your rhetorical opponents, or distinguish between opinions you're sure of and opinions you have only a slight preference for, when you're exaggerating. Satire, no matter how much cleverness goes into it (and I don't deny that satire can be very clever), is a brute-force weapon. It is conducive not to calm, intellectually rich debate, but to shouting matches.
On that note, satire shares a problem with other forms of ridicule, which is that it hurts people's feelings. Now, I recognize that many ideas that are controversial enough to be worth discussing are also controversial enough to offend people (or "trigger" people, as the young folk say). Deep ecology and eugenics are good examples from opposite ends of the left–right axis. But it's a bad idea to unnecessarily hurt people's feelings by how you present an idea, assuming you're trying to have a real argument, or otherwise engage with the people you might offend. Compare
I can't imagine the profound lack of empathy it must take to believe eugenics makes any kind of sense, let alone to promote it in a public forum.
You actually believe in eugenics? Do you have a swastika pin for your fedora?
Ja! Ve vill make der master race! Heil Arthur Jensen!
But eugenics is unethical. Reproduction is a fundamental human right.
The first three examples do not suggest a genuine interest in a mutually enlightening dialogue. They suggest anger and hatred, to various degrees. (Presumably, this is part of the reason the invocation of Godwin's law is said to terminate debates.) They also carry superfluous possible sources of offense, particularly as the degree of irony increases from mere hyperbole (the first example) to ridicule (the second) to full-blown satire (the third): heaven forbid you like fedoras, or you're German, or you admire Arthur Jensen (who had some very dubious beliefs about genetic explanations for racial differences in intelligence but not, to my knowledge, about eugenics, and presumably wouldn't appreciate being compared to Hitler even if he was pro-eugenics). The final example might not be a good argument (its second sentence is arguably begging the question), but it's civil and it makes the speaker's actual view on the matter clear. "Reproduction is a fundamental human right." is by no means the only justification one could have for opposing eugenics, so we couldn't assume this was the writer's opinion in the other cases. On the contrary, in the first three examples, we can see the writer is against eugenics, but not why.
In any case, hurting your opponents' feelings may feel gratifying, but in the context of a serious discussion, it's antisocial. If your opponent started it (i.e., was mean-spirited first), that makes it no better: two wrongs don't make a right. You ought to keep your higher ground. If you've lost hope for any possibility of a mutually productive discussion (which, as a more cynical person than I was when I first wrote this essay in 2013, I recognize is often not in the cards), then just leave. If you're going to keep participating, on the other hand, try to defuse the situation. The angrier people are, the worse they'll be at reasoning and the less willing they'll be to acknowledge when they're wrong. These qualities are obviously poisonous to productive debate.