Suppose that determinism is true. Then determinism guarantees that scientists will believe the hypotheses they do believe them whether they're true or not. If determinism guarantees that each person believes what he does believe whether his belief is true or not, why should I trust any scientist's scientific judgment any more than I trust my own scientific judgment when he and I draw opposite conclusions under the same conditions? On the same supposition, deterministic factors force him to believe what he believes, the same factors force me to believe the opposite conclusion. They may even guarantee that no one can know whether either conclusion is true. Sometimes science undermines its own credibility with its own theories.
That's why scientists need to know some philosophy because they need to reason about truths that are more general than scientific ones. Richard Weaver writes:
The theory of empiricism is plausible because it assumes that accuracy about small matters prepares the way for valid judgment about large ones. What happens, however, is that the judgments are never made. The pedantic empiricist, buried in his little province of phenomena, imagines that fidelity to it exempts him from concern with larger aspects of reality-in the case of science, from consideration of whether there is reality other than matter (Weaver 60)
Weaver believes that sensory experience is only an indirect source of knowledge because we need to know first principles before we can know any other truths. For him, we abstract from particular objects, too. So I think he would he would agree with St. Thomas Aquinas and me. For the saint and me, people abstract completely general ideas from what experience tells us. After you experience enough trees, you'll know what all trees have in common that distinguishes them from every other kind of object. You'll know an essence. You'll discover what you might call "tree-ness," and tree-ness is what you describe in a real definition, a definition that defines a thing rather than a word.
Weaver, Richard M.
Ideas Have Consequences. Chicago: University of Chicago Press, 1948.
Oh how I love the semantics game.