"Only when they must choose between competing theories do scientists behave like philosophers."

"I suggest that scientific knowledge, though logically more articulate and far more complex, is of this sort. The book…"

"To my complete surprise, that exposure to out-of-date scientific theory and practice radically undermined some of my …"

"Somehow, the practice of astronomy, physics, chemistry or biology normally fails to evoke the controversies over fund…"

"History, if viewed as a repository for more than anecdote or chronology, could produce a decisive transformation in t…"

"Out-of-date theories are not in principle unscientific because they have been discarded. That choice, however, makes …"

"Normal science, the activity in which most scientists inevitably spend almost all their time, is predicated on the as…"

"Men whose research is based on shared paradigms are committed to the same rules and standards for scientific practice…"

"Ever since prehistoric antiquity one field of study after another has crossed the divide between what the historian m…"

"If a demarcation criterion exists (we must not, I think, seek a sharp or decisive one), it may lie just in that part …"