# Impressions: Freakonomics

On my flight Boston-Keflavik, I picked up *Freakonomics*, by Levitt and Dubner. It was a fun read that I highly recommend. But a few things struck me about it, so I figured I'd write them down rapid-fire.

There's also a much longer about-Christmas post in the works, but it might not be out until tomorrow.

**(1) "Despite [his] elite credentials, his approach is notably unorthodox."**

I'm not sure what bothers me more: the widespread stereotype that eliteness is inextricable from orthodoxy, or my sinking suspicion that it's not entirely false.

**(2) "He is ... an intuitionist."**

In mathematics, "intuitionism" is a bit of a dirty word. In layman's term's, an intuitionist rejects the idea that a double negative is a positive, and so considers as *invalid* the logic:

**1)** Either A or B is true.

**2)** A is false.

**3)** Therefore, B is true.

It's appealing, because disallowing proofs by contradiction of the negation (*i.e.* the above form) means that every proof of *"X exists"* necessarily gives a mathematical