To have the burden of proof is to be rationally required to argue for or provide evidence for your position. To have a heavier burden than an opponent is to be rationally required to provide better evidence or better arguments than they are required to provide. Many commentators suggest that differential or uneven distribution of the burden of proof is ubiquitous. In reasoned discourse, the idea goes, it is almost always the case that one party must prove the claim at (...) issue to prevent the opposing view winning by default. The following passage is typical of the sort of thing one finds in critical thinking textbooks. (shrink)