The explosion of disinformation about COVID has been a defining aspect of the pandemic. Alongside the virus itself, we’ve been shadowed by what the World Health Organization has called an infodemic. This is widely known, of course, but much less discussed is the role of ostensible “experts” in perpetuating dangerous fictions. Since the dawn of the crisis, a disconcerting number of eminently qualified scientists and physicians have propagated falsehoods across social media, elevating themselves to the status of gurus to lend a veneer of seeming scientific legitimacy to empty, dangerous claims. And these bogus claims, like their pathological namesake, have gone uncontrollably viral.

In March 2020, for example, physician Thomas Cowan insisted that COVID was caused by 5G radio frequencies. This assertion was both devoid of evidence and physically impossible, but that proved no impediment to its widespread acceptance, with anti-5G sentiment accounting for at least 87 arson attacks on cell-phone towers in the U.K. alone. The ostensible documentary Plandemic, starring Ph.D. virologist Judy Mikovits, ratcheted up millions of views with the central thesis that the novel coronavirus is a planned hoax.

Even Nobel laureates in medicine have been culpable; a statement from the late virologist Luc Montagnier that COVID was probably manufactured earned him both the enthusiastic embrace of conspiracy theorists and the enmity of scientific peers who refuted the conjecture as utterly false.

Ineffective treatments ranging from hydrochloroquine to ivermectin to vitamin D and alternative medicine have thrived, too, endorsed by a rogues’ gallery of doctors and researchers. Even as the lifesaving impact of vaccination began to be felt across the globe, a new cohort of impressively credentialed contrarians emerged, spreading mistruths about immunization. The grandiosely named “World Doctors Alliance” is a potent example, boasting among its membership physician Vernon Coleman (an anti-vaxxer activist and author of a book insisting COVID is a hoax) and Dolores Cahill, the once respected Irish scientist whose conspiratorial proclamations became a staple of lockdown protests and COVID denialist disinformation across Europe.

In slickly produced videos shared relentlessly online, these fringe scientists are lauded as experts unafraid to speak truth to power. But it is crucial to note that these individuals, for all their formal credentials, extol a narrative completely at odds with reality, readily refuted by public health bodies the world over. These pseudoscientific, conspiratorial claims are archetypal arguments from authority in which a perceived expert’s support is used to justify positions unsupported by data. Scientific claims derive their authority not by virtue of their coming from scientists but from the weight of the evidence behind them. Pseudoscience, in contrast, tends to focus on ostensible gurus rather than consensus opinion. The only authority a scientist can ever truly invoke is a reflected one, dependent on accurate representation of the evidence base. If they embrace fringe positions and jettison the principles of scientific skepticism, then their qualifications, education and prestige mean absolutely nothing.

Were these claims merely vapid, that would be bad enough. But they are also uniquely damaging to public understanding. Scientists and physicians occupy an extremely trusted position in society, and an imprimatur of scientific legitimacy is a powerful one. This is a trust utterly abused by fringe figures who present qualifications as a proxy for scientific validity. This is superficially convincing to the point that it does not matter that these videos originated in conspiratorial circles; the intrinsic aura of “science” afforded by apparent experts enables them to metastasize far beyond this odious origin. This in turn casts a specter of doubt over the advice of public health bodies, distorting public understanding by presenting rank fictions in the stolen robes of science.

The rise of pseudoexperts is perhaps symptomatic of a change in how we access information. As we become curators of our own media, the traditional gatekeepers and fact-checkers once implicit in most reporting have been increasingly sidelined. This in turn has made us more polarized and reduced our ability to differentiate fact from opinion. Motivated reasoning, our human bias toward cherry-picking only arguments that chime with what we wish were true, most certainly plays a role. The impositions of COVID are manifold; it is not surprising that fringe scientists are inevitably invoked as sources for those with strong feelings against lockdowns, masks and vaccination. Even if we are not ideologically predisposed to such positions, these claims undermine public understanding, blurring perceptions of scientific consensus, nudging us collectively toward fear and distrust.

The dark irony is that these fringe figures weaponize the societal trust afforded to science, unduly amplifying their capacity to unleash serious harm. To mitigate this, we need to keep in mind the vital distinction between “science” and “scientists.” Individual scientists are far from infallible; they can be fooled by subtle mistakes, be haunted by spurious conclusions or even become so ideologically wedded to a belief they bend facts to fit that preconception. Their motivations are human; they can be seduced by the lure of money, infamy or admiration. Science, in contrast, is a systemic method of inquiry whereby positions are formed on the totality of evidence. Crucially, to be labeled “scientific,” ideas should be testable, and those that fail to withstand dispassionate investigation should be duly discarded.

For all their qualifications, fringe scientists fail to uphold this basic tenet of science, as they are united in their willingness to embrace conspiracy theory when their claims are refuted. Lack of evidence for their position is airily dismissed as a cover-up by everyone from the WHO to the entire medical establishment. But this performative outrage is so much sound and fury to distract from the inescapable reality that their positions are completely contradicted by the overwhelming weight of scientific evidence. This is scientifically reprehensible, and staggeringly irresponsible, conduct.

It is entirely understandable that many people are left confused and uneasy by the vocal assertions of fringe figures, but the onus of proof is always on those making grand claims. The history of science and medicine is littered with the hubris of the arrogant and misguided, and mere credentials are no impediment to being wrong; only evidence truly matters. When confronted with the pronouncement of fringe figures, the motto of the Royal Society should always be at the forefront of our mind: “Nullius in verba” (“take nobody’s word for it”).