Scientists don't, when they do science. All they need is calipers, methodology, and math.
I'd add something else to this list: assumptions.
I'm often reminded of something Einstein said about his development of Special Relativity, to the effect that the first and most important step in his work was to scrutinize the assumptions underlying Newtonian physics; as I recall it, the culprit was a Newtonian assumption that rate of passage of time is invariant.
Once I started looking for this sort of thing, I was surprised how many "scientific" statements are actually statements of what scientists currently assume, and which have attained in their minds the status of physical laws. (Such was the case for Newtonian physics, for example.)
Well said, r9etb!
And if you keep digging long enuf, and you'll often (usually) find some kind of metaphysical presupposition at the root.
Thanks so much for writing!
The investigation into such things by Roger Patterson in Evolution Exposed and his rejoinder to each individually excite me to the purchase of his book.
Ladies, his work was published and is well marketed by Answers in Genesis, BTW.
Then again, maybe Free Republic should/would/could create a subsidiary publishing house! A-G, you're the one with the stats on who among us is uniquely gifted for such things, for every aspect of such a money-making, knowledge-spreading endeavor! (I'd personally delight to be involved in such a project!)