In these days of COVID-19, there are many contentious discussions about whether or not to wear masks, whether or not to lift shelter-in-place restrictions, and so on. Usually there's a "consensus" opinion and a "contrarian" position. Whichever will turn out to be right in retrospect, these can often be distinguished by one side having more evidence available to cite. The other side knows that they're fighting against that evidence, so let's look at why and how.

Why would someone want to argue a position other than that suggested by the generally accepted evidence? There are many reasons, none of which necessarily imply evil intent.

• Maybe that evidence does not match their own individual experience, so they think it's inaccurate. Cognitive bias is hard to overcome, and I'm not faulting anyone for it.
• Maybe they feel they have additional - even superior - information sources, that are unfairly excluded from consideration.
• Maybe they believe that the conclusions based on that evidence, while correct, conflict with some higher principle (most often individual liberty).

Often, contrarians are arguing not that the conclusions are wrong but that they're premature or too weak to justify associated policy decisions. Their goal, therefore, is not to refute but to sow doubt. This is almost exactly the same tactic preferred by information-warfare professionals, and the response should be the same.

Here's what doesn't work: long detailed responses pointing out every flaw in the contrarian's position. If their goal is to create an impression of equivalence between two views, nothing serves their purposes better than the tacit admission that their view is worth such effort. That's falling right into their trap. Furthermore, every word that you write gives them another "hook" on which to hang another follow-up, prolonging what shouldn't even be a debate and strengthening the appearance of equal weight. I've seen this time and time again in the last 35+ years of online discussion. If a contrarian makes a particularly weak post/comment full of obvious fallacies, incoherence, or ill will, let it stand. Let them have the last word, no matter how much it rankles. If you don't, here's what will happen.

• People already inclined to believe the contrarian will continue to do so.
• People already inclined to believe the consensus will continue to do so.
• Any fence-sitters (if there even are any) will see the continued back-and-forth, and conclude that the issue is still debatable.
• People on all sides who can no longer (or no longer wish to) follow the debate on facts will start to judge conduct instead. It's easier. If you're right on the facts but come off as condescending - easy to do when you're obviously right - then you've lost and the truth lost with you.

By all means, cite your facts and make your point, but keep it short. Resist the temptation to repeat or elaborate or get in that one zinger that you think will make your interlocutor crawl away in shame (they won't). With that, I'll take my own advice and end here.