Experimenter's regress

In science, Experimenter's regress refers to a loop of dependence between theory and evidence. In order to judge whether evidence is erroneous we must rely on theory-based expectations, and to judge the value of competing theories we rely on evidence, but to detect errors in experiments we must be aware of theoretical predictions, etc. Cognitive bias affects experiments, and experiments determine which theory is valid. This issue is particularly important in new fields of science where there is no community concensus regarding the relative values of various competing theories, and where sources of experimental error are not well known.

If Experimenter's regress acts a positive feedback system, it can be a source of pathological science. An experimenter's strong belief in a new theory produces confirmation bias, and any biased evidence they obtain then strengthens their belief in that particular theory. Neither individual researchers nor entire scientific communities are immune to this effect, see N-rays and Polywater.