Its just human nature to start from a position and investigate outwards looking for facts. It takes discipline and practice to avoid doing this ... unfortunately. And I doubt anyone really reaches that level of objectiveness, instead generally trusting their "intuition" even when they're a practiced scientist.
Ultimately that's why debate and varied opinions are important .. as long as we all meet on equal footing and good intent.
If tomorrow you found out that confessions under torture were mostly accurate, would that fact cause you to accept torture as a policing tool? Probably not.
The core insight of the Enlightenment--that we are all equal--is itself a statement of values rather than a factual observation. In truth, we are not equal.
But if we started with the fact that we are not equal and then tried to build a society out of that, we would end up with a pretty distopian and stratified civilization.
There are certainly things like "most humans value not torturing people" that are factual. Its quite exhausting to drag the lines between a strict definition of "physical law fact" and "known truths about humans" ad nauseam. People value their values, and that's a fact. Saying "we can't value facts as a primary source of judgement because we'll all turn into dispassionate torture robots" requires a suspension of disbelief.
Ultimately that's why debate and varied opinions are important .. as long as we all meet on equal footing and good intent.