Post Hoc, Ergo Procter Hoc

The fallacy known as post hoc, after the Latin term post hoc, ergo propter hoc, meaning "after this therefore because of this," rests on the simplistic idea that if event B came after event A, then A somehow must have caused B. The brain has a natural tendency to associate events that happen close together in time sequence, so this fallacy can easily arise in complex situations. Mark Twain once commented, "When the (civil) war broke out and commerce on the Mississippi River ceased, my occupation was gone. So I joined the Confederacy. I served for two weeks, and then deserted. The Confederacy fell."