Correction to Mark Twain on evidence based practice
This Endpiece attributed the quotation “It ain't what people don't know that hurts them it's what they know that ain't so” to Mark Twain (25 January, p 211). However, a reader has corrected us, confirming that this quotation is attributable not to Mark Twain but to Josh Billings (and in support has cited various sources, including the Penguin Dictionary of Modern Humorous Quotations, Penguin, 1987). A trawl of the web, however, has revealed that people often get it wrong, attributing the quotation in question not to Josh Billings but to Mark Twain—or to Will Rogers or Herbert Stein (or possibly others). The quotation always appears in slightly different forms; indeed, the one cited in the Penguin dictionary is not exactly the same as the one we published.