You wonder how to prove that survival is ‘our great quest without circular reasoning’ I wonder what led you to ask this question. The answer provided by ScepticX seems perfectly reasonable to me, in fact it seems quite intelligent and succinct. Yet you dismiss it as the type of response you were hoping not to get. You say ‘scientism’ will not do you any favors. I ask what sort of favors do you expect from a word, particularly one that I don’t believe is really a word?
Personally, I don’t agree with the premise that human survival is ‘our great quest’ as you put it. Humans, as a species, seem far more interested in death and destruction than survival. It is only a small minority of humans that are truly interested in doing anything beneficial for our species survival. And even they sometimes screw up it up - despite their best intentions.
If you want to actually understand survival, I’d suggest you try doing something truly dangerous, and life threatening and see if you survive. For it is only through surviving that one can truly come to understand what survival really means. And if perchance you don’t survive? One less mouth to feed, then, i suppose.
If, on the other hand you merely want to debate the philosophy of survival – whatever that means - with people intelligent enough to make you think, and challenge you to think for yourself, then I suppose you have come to the right place, but perhaps to the wrong forum. Try reposting you question in the Philosophy forum. ScepticX’s’ response is surely the right one from a scientific point of view.