It's a methodology, not a philosophy. There is no declaration that the universe is an impersonal place, only that it should be treated as an impersonal place unless and until that assumption leads to some contradiction or otherwise proves inadequate. In large part, this is because ascribing material effects to non-material causes doesn't carry much explanatory power along with it. You can easily say "God did it", or "because that's how God wants it" about virtually any aspect of the natural world, but that doesn't really tell you anything you didn't already know. If the question is, for example, "Where does lightning come from?", and the answer is "God did it," well, you're done - your investigation is over, because there's no hook to investigate material causes for this material phenomenon, and hence you don't ever learn anything about the material world beyond the bare fact that it exists and that God is responsible for said existence.
Now, when I said much the same thing on another thread, someone pointed out that you could undertake to investigate how God did these things, and thereby come to investigate the material world. Of course, such an assumption of an external entity does not appear to me to be necessary, nor do I find it plausible that such an assumption would necessarily result in better science, but I think you can do that and still be an honest scientist.
It's a hell of a narrow road to walk, though, because science demands a certain amount of objectivity and intellectual honesty, which may or may not be conducive to maintaining your particular worldview. If you, as a scientist, set out to discover how God brought about the diversity of life on earth, and it begins to look to you like "evolution" is the answer to your question...well, at that point, it may be decision time for you - revise your worldview, or abandon science. Or maybe your worldview is such that evolution being the "how" isn't a problem in the first place - personally, I don't like to tell God what he can and can't do, but that's just me ;)
If some evidence exists that indicates that a higher intelligence is necessary to design life forms...
Here's the problem with all such hypotheticals in this area - nobody has yet managed to explain what the hypothetical evidence would look like. How do we know evidence of ID when we see it? How do we spot intelligent design - especially nonhuman intelligence - in biological structures?
It's one of those questions that looks easy enough to answer at first, but upon closer examination, it proves exceedingly difficult - intractably difficult, in my personal opinion. Maybe you'll have better luck, but the track record thus far is not promising.