The term Quid Pro Quo is an old Latin saying and “principle of law”. The meaning is: An equal exchange or substitution. Latin quid, what? + pro, for + quo, ablative of quid, what?.
Proof in Science & Philosophy
About Gravity: Charles Darwin in a letter to Charles Lyell 
With respect to Bronn's objection that it cannot be shown how life arises, & likewise to certain extent Asa Gray's remark that natural selection is not a vera causa. I was much interested by finding accidentally in Brewster's life of Newton, that Leibnitz objected to the law of gravity, because Newton could not show what gravity itself is. As it has chanced I have used in letters this very same argument, little knowing that anyone had really thus objected to Law of Gravity.
Newton answers by saying that it is philosophy to make out the movements of a clock, though you do not know why the weight descends to ground.
Leibnitz further objected that the Law of Gravity was opposed to natural Religion!
Is this not curious? I really think I shall use these facts for some introductory remarks for my bigger book.
We cannot live by scepticism alone
Harry Collins; Essay; 2009 — Publishe by Nature
Scientists have been too dogmatic about scientific truth and sociologists have fostered too much scepticism.
The term 'science studies' was invented in the 1970s by 'outsiders', such as those from the social sciences and humanities, to describe what they had to say about science. Science studies have been through what my colleagues and I at the Cardiff School of Social Sciences, UK, see as two waves. In wave one, social scientists took science to be the ultimate form of knowledge and tried to work out what kind of society nurtures it best. Wave two was characterized by scepticism about science.
This third wave will be resisted. Post-modernists have become comfortable in their cocoon of cynicism. And some natural scientists have become too fond of describing their work as godlike. Others are ready to offer simple-minded criticisms of deeply held beliefs. But the third wave is needed to put science back in its proper place.