Un-Priori

My physical therapist told me I'd need to ice my knee for a few days. I asked if it would need more than one icing per day. "More than once per day? I should hope so!" she chortled. It was ridiculous to imagine any therapeutic effect at all from a mere single application. I was told to ice three times.

I'm sure she was right, and I of course followed her direction, but here she was making an a priori argument in a situation that couldn't support it. If 5 icings were required, or 20 or 150, one might just as easily ridicule the notion of three daily icings.

Years earlier, a friend invited me along to a Wayne Shorter concert. He had an extra ticket. As we filed into our seats for the performance, I asked how much I owed him. "$100" he said. My mouth fell agape. "A hundred dollars? Really?" He looked at me like I was a boob. "It's Wayne Shorter! A legend! Would you really argue that Wayne Shorter isn't worth $100?"

"Why not $13,000?" I replied. Is Wayne Shorter not worth $13,000? Honestly, a mere thirteen grand sounds like a steal to hear one of the all-time greats!

Ice is therapeutic and Wayne Shorter is great. In these cases, they're indisputable assertions. But neither assertion, on its own, supports a particular numerical conclusion.

I hereby coin the term “Un-Priori Argument” for arguments where the conclusion is presumed to ride along on the self-evidence of an undisputed premise. It’s a form of non sequitur (where the conclusion doesn’t follow from the premise), in which the conclusion tries to borrow authority from the premise. And now that I've pointed it out, you'll see this everywhere.