The February 2007 issue of First Things (www.firstthings.com) has a review of Is Nature Enough? Truth and Meaning in the Age of Science by John F. Haught.
(The review is by Michael Liccione.)
According to the review, Haught believes that theologians should not fear the theory of evolution because evolutionary biology is limited to observing facts and supplying theories based on those observations.
The idea that only what can be shown scientifically can be known at all is scientism, a specific epistemology; that is, it is a philosophical position, not a scientific one.
Haught uses the idea of a "layered explanation" to explain the limited domain of scientific knowledge. Science can explain what is happening and how it is happening, but it cannot explain why it happens. The theological answer to why does the cosmos exist is not a substitute for a scientific answer but exists on a higher layer.
This is related to the idea of causation (or causality), mentioned in the previous post.