the mathematician's power play

Interesting post at the blog The Truth Makes Me Fret.

Here is an article by Max Tegmark about mathematical reality.
Tegmark wants to argue from the existence of an external reality to the existence of a mathematical external reality-- basically that math is all there is. I admit that this "math is all there is" idea is pretty appealing to me. I think that while possibly true in some sense, at the same time it is less powerful than it seems at first.

I go through this mental excercise sometimes: suppose I spend much of my time studying X. Now here is why X is the most important thing in the world. Now repeat this exercise for Y.

For example, economics: We can't survive without resources. Study of exchange and management of resources is thus absolutely crucial.
Now try psychology: obviously thinking is important. We spend much of our time thinking and much of our existence is manifest through our thoughts. Thus, the study of the structure of thinking and its resultant behavior is clearly of the utmost importance, dare I say, crucial?
Repeat.


Ponder Stibbons shows in her post that Tegmark gets his result by a confusing use of the word "baggage".
I suppose Tegmark might find a way around this critique by claiming he didn't quite mean this or that, and I want to read his article more carefully, but as a document, it strikes me as an attempt for mathematical physics to regain the throne (in case it ever lost it).