We philosophers of science have long debated the issue of what counts as evidence for a scientific theory or hypothesis. Today there is as much disagreement as ever. We argue about whether evidence or confirmation should be understood by reference to probability, whether it is quantitative, whether it is inductive, hypothetico-deductive, or neither, whether predictions of new phenomena provide stronger evidence than explanations of old one, whether there are universal standards of evidence or whether such standards vary from one person or community to the next, and even over whether scientists believe hypotheses on the basis of evidence or solely because of interactions with peers.