> Your brain is a structure for learning structures.

And it does so by having specialized structures.

> It doesn't need to have a built-in module for recognizing faces; it wires up a face-recognition system on the fly, from visual data.

Except it does appear to have such a special structure, the Fusiform Face Area. If it did not, people with prosopagnosia wouldn't just have problems with recognizing faces, but would have more general pattern recognition problems.