The ideal of completely correct knowledge is a concept. Scientific knowledge keeps changing, and our ideas about truth change too.’ Dr. Terry Halwes
There are many philosophical and historical theories as to how scientific consensus changes over time. The history of scientific change is extremely complicated, and there is a tendency to project "winners" and "losers" onto the past in relation to our current scientific consensus, it is very difficult to come up with accurate and rigorous models for scientific change. This is made exceedingly difficult also in part because each of the various branches of science functions in somewhat different ways with different forms of evidence and experimental approaches.
Most models of scientific change rely on new data produced by scientific experiment. Karl Popper proposed that since no amount of experiments could ever prove a scientific theory, but a single experiment could disprove one, science should be based on falsification. Whilst this forms a logical theory for science, it is in a sense "timeless" and does not necessarily reflect a view on how science should progress over time.
Among the most influential challengers of this approach was Thomas Kuhn, who argued instead that experimental data always provide some data which cannot fit completely into a theory, and that falsification alone did not result in scientific change or an undermining of scientific consensus. He proposed that scientific consensus worked in the form of "paradigms", which were interconnected theories and underlying assumptions about the nature of the theory itself which connected various researchers in a given field. Kuhn argued that only after the accumulation of many "significant" anomalies would scientific consensus enter a period of "crisis". At this point, new theories would be sought out, and eventually one paradigm would triumph over the old one – a cycle of paradigm shifts rather than a linear progression towards truth. Kuhn's model also emphasised more clearly the social and personal aspects of theory change, demonstrating through historical examples that scientific consensus was never truly a matter of pure logic or pure facts. However, these periods of 'normal' and 'crisis' science are not mutually exclusive. Research shows that these are different modes of practice, especially as ethics and technology adapts with cultural changes.
'The wrong view of science betrays itself in the craving to be right; for it is not his possession of knowledge, of irrefutable truth, that makes the man of science, but his persistent and recklessly critical quest for truth. Sir Karl Popper
The Logic of Scientific Discovery'