2011-01-25
Explanation
This comic is titled "Know Your Logical Proofs" and presents a humorous taxonomy of proof techniques. It begins with three legitimate logical proof methods: Direct Proof (if P then Q; P; therefore Q), Proof by Contraposition (if P then Q; not Q; therefore not P), and Proof by Contradiction (if not P then contradiction; therefore P). Each is shown with both a plain-English description and its formal logical notation.
The comedy kicks in as the comic then introduces increasingly absurd "proof" methods that have nothing to do with actual logic. "Proof by Tradition" argues Q is true because the prover'''s father, grandfather, and great-grandfather all believed Q. "Proof by Intimidation" threatens violence against anyone who asserts "not P." "Proof by Distraction" simply yells "Hey, look at THAT!" and then declares Q while no one is paying attention. "Proof by Extortion" uses a thinly veiled mob-style threat against the listener'''s family, complete with the sound effect of a gun being cocked. Finally, "Proof by Erection" observes that P and Q look like breasts, laments loneliness, and concludes with the emoticon (.Y.) representing cleavage.
The joke works on multiple levels: it satirizes how people actually argue in real life (appealing to tradition, threatening, distracting) while also poking fun at the dry formalism of mathematical logic by rendering these absurd arguments in proper symbolic notation. The votey panel adds a further gag about "Proof by Tradition," noting that the chain of Qs pointing backward can be expressed as a single symbol called "Angry Bearded Q" -- a visual pun on how the symbol resembles an angry face with a beard.