Remember how we used to laugh about flat earthers and climate sceptics? Yeah, me neither. It was hard to pay them much attention when you knew hardly any credible scientist shared their views.
But in the Covid-era, anti-vaxxers and pandemic denialists pose an existential threat.
Some of them protest outside vaccination centres, trying to scare people who are trying to protect their health and the health of their friends and whānau.
The denialists tell us the pandemic is a mirage created by governments and pharmaceutical companies worldwide.
Despite millions of deaths, some claim there's nothing to see here. To them, masks are silly and scanning is for dopes.
I've tried, but you can only change the subject so many times before your head feels like it might explode. How should we talk to science deniers? Do we even bother trying?
Lee McIntyre, a researcher at Boston University's Center for Philosophy and History of Science, and author of How to Talk to a Science Denier: Conversations with Flat Earthers, Climate Deniers, and Others Who Defy Reason says the answer to the last question is yes.
And the good news is, you don't have to be an expert. You just have to be empathetic. And gently point out flaws in reasoning.
In his book, McIntyre analyses science deniers' (who often call themselves sceptics) signature reasoning styles.
He explains the five tropes of science denial reasoning:
Selectivity bias: This involves cherry-picking isolated papers that support an unconventional viewpoint or discrediting a few flawed papers to cast doubt on an entire field of science.
Belief in conspiracy theories: This includes the claim scientists are engaged in a complex and secretive conspiracy.
Illogical reasoning: Including the use of straw men, where the opposing argument is misrepresented, making it easier to refute.
Use of fake experts: People who purport to be experts but whose views are inconsistent with established knowledge. (Learn whether these experts are selling something).
Impossible expectations: The belief that if your opponent isn't perfect, then you're right.
A 2019 study reported in Scientific American showed "technique rebuttal" - pointing out fallacies in these tropes - was effective for laypeople to talk science deniers out of their wrong beliefs.
In essence, technique rebuttal is all about gently indicating where a friend's reasoning is going astray, rather than trying to correct their errant beliefs with more new facts.
Researchers said understanding the five tropes of denialists was more effective than "topic rebuttal", which requires a vast knowledge of science.
The internet has only fuelled science denial, and it takes very few people to sow disinformation.
The Center for Countering Digital Hate earlier this year reported 12 anti-vaxxers were responsible for almost two-thirds of anti-vaccine content circulating online.
McIntyre suggests keeping our conspiracy theorist friends and family close to us. It doesn't help to shut them out.
If we're not getting pushback from people who disagree with us, we can start seeing the other side as the enemy.
He told BU Today in October that science denial is not just about doubt, it's about distrust.
We can't overcome distrust simply through sharing accurate information; we also need face-to-face conversation. "Having the right attitude is the only thing that gives hope of success," he says.
If you listen to the stories of science deniers who have altered their beliefs, writes McIntyre, they "universally report the positive influence of someone they trust".
This person built a personal relationship with the denier, took their doubts seriously, then shared the evidence. "Facts alone were not enough."
He cites the example of an American woman who wrote of her conversion regarding vaccines in a Washington Post op-ed titled: I Used to Be Opposed to Vaccines. This Is How I Changed My Mind.
She explained her old stance stemmed mostly from misunderstanding the ingredients in the vaccines and how they worked.
What changed her mind? "... finding a group of people who were strongly in favour of vaccines and willing to discuss the topic with me."
She writes that those people corrected misinformation and responded with credible research.
It won't always work, of course. By the time someone has ventured down the rabbit hole, they might be too far gone to save.
Questioning someone's anti-vaxx status can be like questioning their faith or their identity.
Still, McIntyre says it's worth planting a seed of doubt in a science denier, even if it takes months or years before they decide to climb out of the hole.
McIntyre thinks we all need to help and rescue. "If you can make progress, that's terrific. If not, at least you tried. We need millions of oars in the water on this problem."
It's not about convincing someone they're wrong. It's about starting the conversation in a way that's empathetic and respectful. Without the right approach, facts are useless.