In the midst of a global crisis, scientists are trying to solve an epistemologically intractable question. Defining whether a drug “works” has never been easy, a task vexed by methodological uncertainty, commercial pressures, statistical errors, or sometimes straight-out bad practices. Facing a new disease, researchers have to rethink what success even means. Is it lower mortality? Less disability upon recovery? Faster recovery? The answers are cryptic because the questions are just educated guesses.