"It should be no news to anyone that the perceptual judgements of individuals can be unreliable for a range of reasons. The challenge, in science, is to arrange the observable situation in such a way that the reliance on such judgements is minimised if not eliminated."

“Science describes not just the observable world but also the world that lies beyond the appearances. This is a rough statement of realism with respect to science.”

“A mature science is governed by a single paradigm.”

“Empiricism and positivism share the common view that scientific knowledge should in some way be derived from the facts arrived at by observation.”

“Scientists are typically good at making scientific progress, but not particularly good at articulating what the progress consists of.”

“Which facts are relevant and which are not relevant to a science will be relative to the current state of development of that science.”

“A far as perception is concerned, the only things with which an observer has direct and immediate contact are his or her experiences.”