"Fight bad ideas with better ideas." The idea is appealing because it satisfies at least two virtuous constraints. The censor is denied entry. The errant belief simply gets cut out by the sharp blades of logic and reason.
Epistemic hygiene: ✔️
Free speech: ✔️
As far as ideals go, it's not a bad one to hold. All things being equal, the free exchange of ideas is preferable to their restriction; less wrong beliefs are better than more wrong ones. But, in some cases, the rule — fight bad ideas with better ideas — is the exact Siren's call that allows for the former's reproduction because a lot of bullshit is prionic.
You've probably at least heard mention of prions before in their particular variants (e.g. "mad cow disease," Creutzfeldt–Jakob disease, etc). But for those unfamiliar (and with the IANAB[iologist]) caveat),
A virus uses cell machinery to reproduce more of itself. Prions encounter good (read: correctly functional) versions of themselves, then bend them into dysfunctional shapes.
Replication by contact.
I think a lot of ideas are like this, too, which may offend a lot of people's enlightenment sensibilities and popular delusions. The counter-argument goes something like,
If I expose myself to bad ideas, I will resist them, no harm done. Meanwhile, by ensuring my intellectual promiscuity, I'll also (re-)discover great ideas, which I'll subsequently adopt.
Rationality acts as a ratchet.
And it is! Or, at least can be. Again, this is not a bad way to look at the world — it's a good one. But, trouble generally arises when we imagine ourselves invulnerable even though we can readily observe others obviously suffering upon exposure.
And some ideas really do seem to fuck people up.
I don't mean this in the sense of "this true idea cripples something vital." It's more like: exposure to this idea reshapes how you see the problem in a mistaken way that recreates it.
Many such cases.
Setting aside Enlightenment romanticism, it's also challenging from a progressive perspective. For those not enthralled by explicit censorial passions, to do something (in the context of expressed, repugnant beliefs) still feels like it must be superior to doing nothing. I've certainly felt that way. (And acted upon the impulse.) But there is nothing which demands that must be true.
Sometimes, "sunlight is the best disinfectant." Sometimes people do foolishly choose to ignore things merely because they are unflattering. But neither case precludes the other very real possibility: sometimes the reaction itself is what provides the raw material for the context's continued propagation. Own goals are actions, too.
The analogy breaks down once you notice that the misshapen ideas animating people seem to manifest as differing forms. (Which is why this one about toxoplasmosis gondii also works very well.) Still, I like it because it highlights a case where there isn't an immunological fix. Your best and only option for prionic diseases?
Avoid exposure.
No, there isn’t a fast and frugal rule that makes it easy to delineate prionic contexts from others which are simply unpalatable or noisy or adversarial. The point is merely to admit the possibility, if only so you can ask yourself: is this one worth the exposure risk? (Think: whatever cultural war issue is currently trending on twitter.) Prionic contexts are insidious in that they seem capable of not only rendering your answer momentarily less than sober — they seem to perpetuate the intoxication in some fundamental, structural way. And since it's your perception that’s influenced, you may not notice the deleterious effects.
Related stuff
This post is just this tweet,
decadently expanded after I realized in some other tweets that I still wanted to spend some time with it. It’s also probably influenced by The Toxoplasma of Rage (which I finally read recently) and There is No Antimemetics Division (which I read recently after learning about it in this substack post, Variant Xi). Semi-related in that my brain thought of it while writing: Derek Lowe’s Things [Chemicals] I Won’t Work With series.