There is no need for the scientist to go into whether an observation was made, nor into the who, what, when, or where. The data on which scientific theorizing is based are rather the propositional contents of the instrument readings recorded, or the facts detected thereby.
Ernest SosaLowered reliability obviously yields a lesser competence. But lowered breadth does so as well.
Ernest SosaIn arriving at the relevant theory about the specifics of our faculty of vision we will presumably use our eyes to gather relevant data. Based on such data we come to know about the optic nerve, the structure of our eyes, the rods and cones, etc., so as to explain how it is that vision gives us reliable access to the shapes and colors of objects around us. In reliably arriving at that theory we thus exercise the very faculty whose reliability is explained by the theory. There is no vice in this sort of circularity.
Ernest Sosa