Re: Materialism will always turn on itself
You are using a non-evolutionary concept of fitness here. In evolution, fitness is an analytic concept, defined tautologically as seen from the successful genes of cumulative adaptation. Therefore just because we imagine that a trait is adaptive, we do not in fact know this to be the case for the future, since something that seems adaptive in the absence of a threat can prove maladaptive when the facts change.
An example is the belief that low-fat diets are healthy. People imagine they become fit by eating food labelled as low fat, but modern medicine is suggesting that the traditional high carb food pyramid fails to address how sugars and fats metabolise differently. But that just illustrates that an idea about fitness is untrue, if the science is that high sugar and starch diets produce worse results with heart disease and cancer and obesity and diabetes.
The same principle applies in genetic evolution: megafauna of the Americas and Australia seemed to have high fitness, but were not adapted to the emergence of human hunters – a new reality - and went extinct. The point is that apparent fitness may not be real fitness. So for humans, if we wish to remain fit to live on earth, it is essential to study reality and adapt to it, not complacently imagine that our dreams are true.
Consider ant’s quote that he sees as a refutation of materialism: "Given an arbitrary world and arbitrary fitness functions, an organism that sees reality as it is will never be more fit than an organism of equal complexity that sees none of reality but that is just tuned to fitness."
The concept of "an organism that sees none of reality but that is just tuned to fitness" is logically absurd. To be tuned to fitness is to see reality.
Materialism essentially argues that nothing trumps the laws of physics. Arguing otherwise suggests there is a supernatural power that could prove human knowledge of physics is incorrect. It is reasonable to say knowledge is partial, but it is fanciful speculation to assert that scientific knowledge is incorrect, since the evidentiary methods of science provide the highest available standard of knowledge. The real problem of "an organism that sees none of reality but that is just tuned to fitness" applies far less to materialism than to religious mythology, which develops ideas that seem to be fit but which often conflict with evidence.
As well, for materialism, “fitness functions” are not “arbitrary”, but are assessed methodically against evidence to develop a consistent explanation of the evolutionary fossil record. Evolutionary biology is materialist, and presents our best available framework to assess what traits are fit. If anything "will always turn on itself", popular religious ideology will, since its values are determined more by popularity than by accuracy.