It is profound and earth shaking...
2009-11-09 · Original WordPress address
... every time I run into a statement like this: "But all interesting models involve unrealistic simplifications, which is why they must be tested against data."
We can know things a priori, but we can't know how important those things are a priori. A model can tell us how a particular mechanism operates, but it can't tell us how important that mechanism is. Effect size can only be determined by looking at the data.
I'm sure there's something wrong with my brain that can't internalize this fact. I just read Landsburg's Big Questions and this was his major theme. (BTW, I liked the book and here's a review at /.)