Mechanistic vs. Teleological Explanations?

Because you can substanciate mechanistic explanations more than teleological ones, which makes for better science, as opposed to philosophy.

With teleological explanations how do you ascribe and measure intent or purpose?

I don't believe the two are mutually exclusive. Physiological processes (eg, osmoregulation) are strictly definable from a mechanistic point-of-view, and they are also understood to be teleologically oriented, unlike the broader aspect of, say, evolutionary processes, which are not teleological. It really depends on what specific processes one is dealing with and one's interpretation of "mechanistics."

This is just my brief opinion (and I'm more into hard science than philosophical interpretation), but I would be interested in knowing *who* said that mechanistic terms are more desirable...