When assessing the validity of a scientific theory, the available evidence should not be weighted equally as if it were equally valid. Rather, the evidence must be prioritized according to the level of confidence that it provides. Evidence that provides high confidence must be prioritized over evidence that only provides low confidence.
Guidelines for the practice of medicine and agencies like the Food and Drug Administration have long recognized that higher confidence evidence is:
1) repeatable, 2) obtained through prospective study (i.e., through experiments designed in advance to block out confounding factors, rather than through retrospective study), 3) directly measured (e.g., blood pressure measured directly via an arterial catheter, rather than indirectly measured via a cuff around the arm), 4) obtained with minimal bias, 5) obtained with minimal assumptions, and 6) summarized with sober
judgement, not amplified or extrapolated beyond the experimental conditions.
These 6 criteria can be applied to any field of science to indicate the relative level of confidence in the available evidence. The criteria are not black-and-white, but rather provide a spectrum of levels of confidence.
Applying these 6 criteria to the evidence for evolution results in a clear dichotomy between evidence that only provides very low confidence and evidence that provides very high confidence.
The commonly cited evidence for evolution (e.g., the fossil record, homology, and vestigial organs) do not meet any of the 6 criteria for high-confidence science.
For example, the process that produced the life-forms found in the fossil record cannot be repeated, cannot be directly measured, and cannot be studied prospectively.
Also, interpretations of the fossil record are replete with bias and are based upon many assumptions (for example, we are asked to assume that a life-form that is not found in a given layer of fossils did not exist at that time, yet we also are asked to assume that absence of
transitional fossils in the fossil record does not imply that they did not exist).
Finally, the interpretation of the fossil record (i.e., the effort to explain how the life-forms contained in the fossil record came to exist) extrapolates far from the actual evidence (fossilized bones) to try to explain the process responsible for the origination of the life-forms. The very low confidence provided by this type of evidence cannot provide clarity; it can only provide fuel for endless debate.
In stark contrast, experimental evolution studies like Richard Lenski’s Long Term Evolution Experiment (LTEE) meet all 6 criteria and provide very high confidence.
Experimental evolution can be repeated, can be studied prospectively and directly measured, with minimal bias and assumptions, and the results can be summarized with sober
The evidence from these high-confidence experimental evolution studies simply must be prioritized over the low-confidence evidence.
Yet, biology textbooks routinely prioritize the low-confidence evidence over the high-confidence evidence. The high-confidence evidence from experimental evolution studies
painta highly constrained picture of evolution.
For example, Lenski’s 70,000 generations of E. coli show that evolution is highly constrained – unable to produce the innovations necessary to change body plans over time or to produce new molecular machinery. The orphan genes that are prevalent in all life-forms cannot be explained by the evolution observed in these studies.
When high-confidence evidence is appropriately prioritized over low-confidence evidence, the result is a profound new view of evolution – one that they did not teach you in biology.
That’s all correct, of course, and the reader is invited to peruse Stadler’s 2016 book. But the reality is, few people of consequence care for the actual science. Most want to be seen as “pro-science,” even if that requires them to endorse what they know to be falsehoods or suspect to be nonsense. The alternative is to be seen as “anti-science,” for relying on a reasonable interpretation of the available evidence.
Dedicated political operatives can usually produce far more grief by intention than evidence can produce by its mere existence. Why should we be surprised when we see nonsense proliferating year after year, even despite clear patterns of evidence?