Epidemiologists in the 1950s faced the criticism that their evidence was “only statistical.” There was allegedly no “laboratory proof.” But even a look at history shows that this argument was specious. If the standard of “laboratory proof” had been applied to scurvy, then sailors would have continued dying right up until the 1930s, because until the discovery of vitamin C, there was no “laboratory proof” that citrus fruits prevented scurvy.
