Despite what you sometimes hear from eight-year-olds, pundits, lawyers, politicians, chat-room trolls, and UFOlogists, "proving a negative" is not just not "philosophically impossible" but often easily accomplished. One of the simplest ways to prove a negative is via a "proof by contradiction". Proving that a claim or assertion is false can be a simple matter of recognizing what would have to follow from that claim and also demonstrating that it could not or did not. We see examples of proof by contradiction regularly on Free Republic. If it had been true that "Tea Partiers spit on Emanuel Cleaver and called...