Scientists and historians can cite many cases of scientific and technological claims, hypotheses, and proposals that, viewed in retrospect, have apparently taken an unaccountably long time to be recognized, endorsed, or integrated into accepted knowledge and practice. Indeed, some have had to await independent formulation. (Hook 2002, 3)
(….) One may classify at least five grounds on which scientific claims or hypotheses—even those later achieving widespread recognition or endorsement—may be rejected at first offering. In addition to prematurity …, investigators may reject or choose to not follow up on a scientific report or hypothesis because (1) they are unaware of it, (2) having reviewed it, they judge it to be of no immediate relevance to their current work and therefore ignore it, (3) they harbor inappropriate prejudice against some aspect of the claim or its proponent, or (4) it appears to clash directly with their observation or experience. (Hook 2002, 4)
(….) Less readily overcome obstruction may stem from strong social forces—religious, ideological, political, and economic—that lead to challenge, rejection, or suppression. In practice, the only remedy may be to seek expression and circulation of the unrecognized, inhibited, or suppression ideas, proposals, and interventions in areas and social climates where the prohibitive factors do not reign. But in principle, in an enlightened society one may suggest some goals, some general social solutions to overcome the barriers. As obvious as they may be, I believe it worthwhile to list some of them: limitation of economic suppression of new inventions or useful technology, encouragement of ideological tolerance, opposition to implacable doctrinaire social forces, and most important tactically, attempts to disconnect the apparent implications of scientific discoveries from the feared ideological consequences. (Hook 2002, 6)
Factors related to but distinct from more global social forces concern resistance at the individual level. New scientific and technical discoveries may threaten not one’s economic welfare or ideological persuasion but rather the “psychic capital” invested in current scientific views—some involving one’s own work—challenged implicitly or explicitly by a new report. Of course the longer one has held views and invested energy in them, the more reluctant one may be to alter them. This inevitably results in conceptual inertia that some have associated with aging. And ranker reasons than those produced by hardening of cerebral arteries or of scientific beliefs may arise from prejudices of culture, nation, gender, ethnicity, or race. (Hook 2002, 6-7)
All these sources of resistance to discovery originate in what some have termed the “externalist” factors influencing science. And for all the above factors, one may, in principle, suggest some types of science policies to address them. For instance, the review of work by referees without knowledge of its authors, as currently practiced by some journals, clearly diminishes effects of some types of prejudices that inappropriately inhibit publication. Editors close scrutiny of reviewers’ judgements may enable them to distinguish opinions based on wounded psychic capital from legitimate methodological objections. (Hook 2002, 7)
 For those not familiar with the term, it refers to factors extrinsic to the putative value-free application of the scientific method. Economic and/or social factors influencing scientific inquiry are externalist. This is opposed to an “internalist approach,” which focuses on those aspects of scientific inquiry seen traditionally as free of values except for the search for truth. The image most scientists have of the ideal working of science is of course the latter. Concern with issues of acceptance of a theory based on replication, falsification, and so on may be regarded as primarily internalist, and concern with those of class and economic factors as primarily externalist. But as has been pointed out on many occasions, it is really not possible to separate those absolutely. See, for example, Nagel 1950, esp. p. 22.