There are two basic strategies for arguing with someone who you disagree with.
The first is to presume good faith on the person you disagree with, presume them to be a mostly honest truth-seeker, and employ logical reasoning, facts, figures, mathematics, and statistics to convince them. This strategy requires that you check your emotions and refrain from morally judging the person with whom you argue.
The second strategy is to claim the moral high-ground as soon as the argument begins, and get very upset at the person who holds an unapproved opinion. You presume (or at least *act* as though you presume) bad faith on the part of the person you disagree with. And you cast them as culturally backwards, or otherwise stupid or wicked.
I think the second strategy is sometimes called for. I see it as a commitment strategy. Sometimes you have to get something done and there is no time for the niceties of an open inquiry. Suppose you are standing up to the king of the most powerful nation on earth. You could write “A Philosophical Treatise Defending Novel Moral Claims of the Signatories.” Or you could write, “We hold these truths to be self-evident…” and berate the king for his misbehavior. You commit strongly to a position, and you signal that you are unwilling to reconsider. It’s perfectly rational to do this in some contexts. If someone proposes a return to state-sponsored racial segregation or the death penalty for marijuana use or mandatory licensure for the act of becoming a parent, there is no reason to take them seriously. If a proposal is self-evidently morally despicable, it’s sometimes appropriate to simply shout it down.
The problem arises when you jump the gun too early. You may commit to the *wrong* proposals, and it might turn out that the people you are insulting actually have something meaningful to say. If you always use the emotional commitment strategy, you end up looking silly. Because half the time you’re probably wrong, which poisons your credibility for the other half of the time. There are people who are willing to change their minds and who respond to information and logical arguments; I’ve seen people change their minds very quickly when they realized they were mistaken about something. On the other hand, few people respond well to being scolded about their misguided values. You may manage to shut someone up by making certain ideas unwelcome, but you are very unlikely to change hearts and minds with this approach. In fact, this strategy is likely to leave a silent majority seething with indignation, but still lurking in the background. They don’t publicly air their unwelcome ideas anymore, but they still hold onto them. They may even vote a walking avatar of their bigotry into office.
Personally, I’d like to see quite a bit more of the first approach. Be a little more willing to consider ideas you don’t like. People who hold them aren’t all stupid or evil. At least understand the arguments of their more articulate proponents. Nothing important is going to change unless we all do this a little more often. Moral progress happens because some of those “morally despicable” ideas turned out to be right.
(I wrote most of this post over a year ago. With Donald Trump now a stone's-throw from the Oval Office, I couldn't resist sharing.)