At stake is a question of the quality of information that should be taken seriously in public discourse and how that information should be communicated. Science may be the most powerful engine for grasping reality, but it suffers a rhetorical disadvantage. In science, the burden of proof falls on the one aiming to overturn the “null hypothesis”—the default position that one thing doesn’t cause another. But conspiratorial thinking is fuelled by the inverse: self-assured conjecture that demands a level of refutation no amount of evidence can offer. Proving the absence of a connection will always be harder than speculating about its existence. The language of science is measured and provisional; the language of politics is declarative and bombastic. In September, President Donald Trump told pregnant women to “fight like hell” not to take Tylenol, because of a potentially increased risk of autism in children; his Food and Drug Administration clarified that “a causal relationship has not been established and there are contrary studies in the scientific literature.” Tylenol, the agency wrote, remains “the safest over-the-counter” option for treating fever or pain.