Truth versus usefulness

Alvin Plantinga

As I said in a previous post, natural selection is the statistical observation that, in general, individuals better adapted to their environment tend to leave more descendants than those less adapted. It is, therefore, a question of usefulness. A trait that will increase the reproduction of an individual is, in principle, statistically favored by natural selection.

In my popular science book published in Spanish (Biological evolution and cultural evolution in the history of life and man) I mentioned that 

Evolution acts in the same way, both on life and on culture, although its way of acting is adapted to the specific environment on which it is applied (genes, nervous systems or cultural elements). 

This means that natural selection does not act only on the physical characteristics of living beings, but also on cultural characteristics (such as ideas), which apply especially and uniquely to man. If ideas are useful, they will in principle be favored by natural selection and will reproduce (that is, they will be adopted by more individuals).

But in the case of ideas, in addition to their usefulness, another criterion can be applied: are they true or false? Obviously, the two criteria are not identical. It is true that a useful idea can be true, but it also may not be true. We have two distinct sets of ideas, those that are true, and those that are useful, as in the following graph:

It is obvious that there are useful but untrue ideas. To see this, just look at how our politicians exploit many false ideas, which are obviously useful to them, even though they are false.

In science, the criterion of truth has (or should have) priority over the criterion of utility. In other words, facts must take priority over theories. For example, Newton’s theory of gravitation proved its usefulness when it led to the discovery of planet Neptune, but it failed when it was used to predict the existence of planet Vulcan. During 60 years, astronomers tried to find this planet without success. In the end, it was recognized that Newton’s theory, although very useful for making calculations in the solar system from the distance of planet Venus, was not valid in the vicinity of the sun, so a theory more in line with the truth had to be found (Einstein’s General Relativity). In short: in science, to be useful, a theory must also be true.

Consider the following reasoning:

1. The materialist interpretation of the theory of evolution claims that all our reasoning and beliefs have been favored by natural selection. They are therefore useful, but they don’t have to be true, for truth and utility are independent criteria.
2. The theory of evolution is a belief obtained as a result of reasoning. Therefore, if materialism is true, the theory of evolution does not have to be true.
3. Therefore, materialism and the theory of evolution are incompatible.

C.S. Lewis

This is the EAAN argument (Evolutionary Argument Against Naturalism) of Alvin Plantinga, who proposed it in his debate with Daniel Dennett. Dennett answered with a classic fallacy: the appeal to ridicule, arguing that believing in God is the same as believing in the existence of Superman or space spaghetti. This reaction is relatively frequent in debates between atheists and believers. Another often used fallacy is sidestep the issue, as when someone tries to discredit Christianity by arguing that a crowd of Christians murdered Aspasia.

The EAAN argument develops an earlier one put forward by C.S. Lewis in chapter 3 of his book Miracles, which was later expanded by the philosopher Victor Reppert in his book C.S. Lewis’s Dangerous Idea: In Defense of the Argument from Reason.

The same post in Spanish

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Manuel Alfonseca