Last week, the Trump administration announced a forthcoming ban on e-cigarettes, following news stories of a spate of deaths from vaping. The Wall Street Journal, on Friday the 13th, published both an editorial and an op-ed piece suggesting that any harm from e-cigarettes is minor and unproven, and counterbalanced by the good they do in helping smokers quit. That e-cigarettes help smokers quit makes sense, and seems reasonable. The Journal opinion writers therefore accept it as fact, as we all do with many things that seem like they must be true. Surprisingly, though, the scientific evidence is that e-cigarettes don’t help smokers quit. A meta-analysis of 38 smoking-cessation studies found that, overall, the odds of quitting were 28% lower for e-cigarette users than for control groups (see last week’s Weekly Brief). As Will Rogers said, “it’s not the things we don’t know that hurt us, it’s the things we know for sure that ain’t so.”