If arguing against those beliefs worked then by your own arguments we should see the amount of believers dwindling over time. Yet as they gain exposure even when people attempt to debate them in good faith, their numbers grow.
How do you explain this?
So to me, your comment comes across as “But what about those cases where what GP said is true?”
But can you be more specific? What consequences can you name, especially in the US? I'm not aware of there being almost anything in the US, except that they might not be allowed into some schools, which barely even counts as a punishment.
And yet the idea proliferates wildly.
But Bredow fell foul of the law because she reneged on agreements with her former spouse dating back to November 2016 to have the boy immunised."
Sounds like an edge case that's more about custody than legal rules over vaccination.
The consequences for people not vaccinating their kids goes beyond just belief. Even then in America we're incredibly lax on those people despite the fact that it seems to be growing movement fueled by quackery.
I think we can, and indeed should argue against such ideas. The goal is not to convince a zealot that his views are wrong, but rather convince the majority of those on the sidelines that those ideas are stupid and will lead to no good. If the ideas are outlandish, arguing against them on merits is easier, not harder. As long as the vast majority of the society sees those ideas as crazy, arguing them stays pretty harmless.
And what is the alternative to arguing on merits? It is tempting to be able to silence unpopular views, but that can backfire -- tomorrow control could change and someone might deny us the ability to speak. "I know the world is flat" needs a better answer than "No! It is round, end of discussion".