A jury needs “proof beyond a reasonable doubt” in order to convict a defendant of a crime. The standard is vexingly difficult to pin down, but some legal epistemologists have given this account: knowledge is the standard of legal proof. On this account, a jury should deliver a guilty verdict just in case they know that the defendant is guilty. In this paper, I’ll argue that legal proof requires more than just knowledge that a defendant is guilty. In cases of (...) “merely predictive evidence,” a jury knows that the defendant is guilty but does not have legal proof. What are they missing? Evidence that is causally downstream from the crime. Legal proof requires a “smoking gun.” The point generalizes outside of the courtroom. A professor needs to read a term paper before assigning a grade, even if she knows the student will produce A + work. You may know that your roommate will forget to water the plants while you are away—she is scatterbrained and always forgets these things—but you can’t blame her until you get back home and see that the plants are wilting. In order to have appropriate reactions or reactive attitudes, we must respond causally to what other people have done. (shrink)