Karl R. Popper. 1968. The Logic of Scientific Discovery, 2d ed. New York: Harper & Row. Chapters 1.0-1.1, 1-3-1.8, 3.0, 3.12, and 3.16.
Intellectual honesty does not consist in trying to entrench or establish one’s position by proving (or probabilifying) it—intellectual honesty consists rather in specifying precisely the conditions under which one is willing to give up one’s position. The history of science has been and should be a history of competing research programs/paradigms, which is good for progress.