Just-So Stories

On this week’s episode of Skeptically Speaking, host Desiree Schell interviewed Mark Changizi about his book, The Vision Revolution. I listened to the live taping this past Sunday at what I believe George RR Martin would have referred to as the “hour of the eel” here in England.

Changizi is never short of interesting ideas, and a researcher should always make the strongest case for their ideas that they can. Unfortunately, I have some issues with the evidence supporting that “strongest case” and the way he presents it:

Assumption of natural selection. It is a common fallacy to assume that the existing features of any organism must be the product of natural selection. This is, in part, a result of the influence of the success Richard Dawkins’ books, such as The Selfish Gene, which focuses heavily on selection. Selection, however, is but one of several forces of evolution (i.e., drift, mutation, and migration) and should not be preferred without compelling evidence. Selection is not a legitimate null hypothesis. Starting from the position that every interesting feature requires a natural selection based explanation is not in accord with current evolutionary theory or the scientific method.

Natural selection as the “designer”. The language is evocative, and as such, is not technically flawed. It does have the effect of making one sound eerily like an employee of the Discovery Institute and suggests that the desire for selective explanations is motivated by a similar conviction that biological systems are too complicated to have evolved by chance.

Ask for evidence. In response to requests for evidence testing his theories, Changizi provides evidence that his theories are plausible. This is good, but not the same as direct testing. The theories are not truly predictive either. They are not predicting unobserved phenomena. They do have the feature of being consistent with previously observed phenomena. A predictive theory should suggest an experimental design we could use to evaluate it. His neurobiology brings to mind string theory. It is mathematically plausible. It is consistent with prior observations. We have no ability to test it.

Is “Why?” > “How?” I like “why” questions; but this is not an “either/or” situation. Understanding “how” a system works fundamentally constrains the set of reasonable answers to “why?”. Theories can get predictions right at a certain level of resolution, but may fall apart or impede progress as we learn more. Newton’s approach to physics remains wonderfully predictive for macro objects; but he got the “how” wrong. Learning more about the “how” (i.e., particle physics and quantum mechanics) is what enabled the microelectronic revolution and this post to be written.

Or, to be more on point, Darwin developed a great theory describing “why” we see the diversity of life that we do. He, however, got “how” variation was created and passed on terribly wrong. Initially, this was not that important to natural selection or evolutionary theory. Eventually, the insight provided by Mendel’s genetic discoveries was necessary to develop evolutionary biology as we know it today.

Just-So StoriesIt is one thing when an evolutionary biologist of Michael Lynch’s reputation lectures his fellow scientists about spinning evolutionary “Just-So Stories” to make their papers appear more interesting. It is another thing to have the critique come from someone who has published a theory that is actually one of Kipling’s* Just-So Stories.

In conclusion, I like a compelling and thought provoking idea. I like them presented with confidence. I liked them even better when they are based on a solid understanding of evolutionary theory and include ways to test them.
*Kipling is brilliant. He also hated camels, which is irredeemable. Camel’s are bad-asses of the first degree.

Author: Josh Witten


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