You’ve probably seen at least one of those funny ads from DirecTV urging you to get rid of your cable television service. One of them goes something like this: When the cable company keeps you on hold, you feel trapped. When you feel trapped, you need to feel free. When you need to feel free, you try hang-gliding. When you try hang-gliding, you crash into things. When you crash into things, the grid goes down. When the grid goes down, crime goes up. When crime goes up, your dad gets punched for a can of soup. So, get rid of cable, change to DirecTV. The comedic element of the ads obscures the fact that they illustrate, albeit loosely, an effective method of argument or…