Newton said many things, none of which were taken on faith, and all of which were only believed insofar as they could be proven by evidence. When environments and situations were found where they did not match the evidence, they were superseded by more general ideas that did match the evidence, and also still matched the evidence in those places where Newton's ideas did.
In an ideal world perhaps; historically, the process has not been nearly so tidy. Thomas Kuhn's Structure of Scientific Revolutions speaks extensively, and elegantly, to this process -- one which is not, in fact, dissimilar from the process of change in many places outside of science. The first section of the Emory outline I linked to earlier, has a (very) bare bones intro which doesn't really do Kuhn justice, but might be useful here:
Quote:
A. A scientific community cannot practice its trade without some set of received beliefs (p. 4).
1. These beliefs form the foundation of the "educational initiation that prepares and licenses the student for professional practice" (5).
2. The nature of the "rigorous and rigid" preparation helps ensure that the received beliefs exert a "deep hold" on the student's mind.
C. Normal science "is predicated on the assumption that the scientific community knows what the world is like" (5)—scientists take great pains to defend that assumption.
D. To this end, "normal science often suppresses fundamental novelties because they are necessarily subversive of its basic commitments" (5).
E. Research is "a strenuous and devoted attempt to force nature into the conceptual boxes supplied by professional education" (5).
F. A shift in professional commitments to shared assumptions takes place when an anomaly "subverts the existing tradition of scientific practice" (6). These shifts are what Kuhn describes as scientific revolutions—"the tradition-shattering complements to the tradition-bound activity of normal science" (6).
1. New assumptions (paradigms/theories) require the reconstruction of prior assumptions and the reevaluation of prior facts. This is difficult and time consuming. It is also strongly resisted by the established community.
2. When a shift takes place, "a scientist's world is qualitatively transformed [and] quantitatively enriched by fundamental novelties of either fact or theory" (7).
Kuhn's basic point is that rather than evolving or moving forward incrementally, science progresses explosively. One only has to look at the global warming brouhaha to see a Kuhnian confluence of science, pseudo-science, believers, apostates, politics, and economics working up to what may, or yet may not, be a paradigm shifting moment. Scientists are not always the bastion of rationality in that mix.
