14 April 2012

Pedophilia, the brain, and cause-and-effect

One of the questions I commonly receive about MRI research on pedophilia is: How do we know what causes what?  Comparing the brain scans of pedophiles with non-pedophiles gives us a correlation, and correlation does not necessarily mean causation.

It is true that correlation does not equal causation, but that does not mean we are powerless about it either.  To understand how to attack this kind of problem, we need to recall a few important (but pretty rarely discussed) principles of science:

First, no scientific statement will ever be 100% proven.  There is no such thing as a perfect study.  That is, anyone will always be free to reject any result, claiming the lack of perfection of whatever study(ies).

Next is parsimony: Because we cannot prove anything, the best science can do is explicate each of the possibilities and to pick the best answer available. In science, the best means the most parsimonious; that is, the simplest explanation for the data.