A highlight of the new book from Discovery Institute Press, The Magician’s Twin: C. S. Lewis on Science, Scientism and Society, is its clear presentation of Lewis’s argument from reason. The argument shows that any rational proposition advanced to support materialism undermines itself. John West summarizes in Chapter 7 (page 155):

…Lewis argued that reason cannot be accounted for by an undirected material process of chance and necessity such as natural selection acting on random mutations. If reason could be accounted for in this way, according to Lewis, we would have no reason to trust the conclusions of our minds, including the conclusion that our minds are the products of a material process of chance and necessity.

This argument becomes almost self-evident the more you think about it. In the book, the comeback arguments are addressed in detail, leaving no escape for the materialist: affirm materialism, and you abandon rationality. Let’s see how the argument works in a real-world example from Nature, “Biology and ideology: The anatomy of politics,” by Lizzie Buchen. She advances the proposition that, “From genes to hormone levels, biology may help to shape political behavior.” (Emphasis added.)
It’s a nuanced case, because Buchen does not try to defend the notion that genes and hormones determine political beliefs; they just shape them. Her focus is clearly on the evolutionary processes that make humans act like such weird political animals. From the outset, it looks like she will have a challenge exempting herself from the rest of humanity — otherwise her readers could turn the argument against her and claim her evolutionary notion was shaped by hormones and genes.

An increasing number of studies suggest that biology can exert a significant influence on political beliefs and behaviours. Biological factors including genes, hormone levels and neurotransmitter systems may partly shape people’s attitudes on political issues such as welfare, immigration, same-sex marriage and war.

Right away, two problems leap out: (1) the fact that members of the same family often split on political issues, and (2) the fact that some people drastically change their political orientations when exposed to convincing arguments, without their genes and neurotransmitter systems changing. Buchen continues:

“People are proud of their political beliefs,” says John Hibbing, a political scientist at the University of Nebraska-Lincoln. “We tend to think they’re the result of some rational responses to the world around us.” But in fact, a combination of genes and early experiences may predispose people to perceive and respond to political issues in certain ways.

In a discussion of “Innate Ideology,” Buchen gives a short history of studies reinforcing the idea that biology shapes of political beliefs. In a 1986 study, for instance, Nicholas Martin found more similarity in the beliefs of identical twins than between fraternal twins. The time was apparently not ripe for acceptance of the implications:

Although Martin’s study had obvious implications for political science, researchers in that field ignored the work. The eugenics movement in the early part of the twentieth century and Nazi theories about the biology of human differences had made political scientists extremely wary about topics that examined genetic differences among people.

It’s interesting to note at this point that the scientists became wary for rational reasons — not because their collective hormones were altered. The wariness slowly wore off, Buchen continues, with follow-up studies apparently yielding similar results. She is fair to point out, though, that some studies were not definitive, and that opposition remains strong in some quarters. Fortunately, she does not push the deterministic thesis too hard:

If other complex behaviours and traits are any indication, the answer is not going to be simple. Even for traits known to have a very large genetic component, such as height, the evidence points to the influence of thousands of genes, each applying a feather-light force. So it seems unlikely that a small number of genes can push someone towards being a liberal activist, a social conservative or a libertarian.

Even so, whether it’s thousands of genes or a few, her argument is going to have to face Lewis’s “argument from reason” challenge. Buchen next examines whether personality, hormones, or “visceral reactions” can help explain people’s political orientations. Each of these are non-rational, physiological influences potentially undermining Buchen’s proposition.
Her final hypothesis is that the emotional “disgust” response might shape political orientation, especially the influence of negative ads. In the end, she leaves the reader with no clear defense of biological determinism:

Regardless of whether biology shapes political choice, it may affect a person’s likelihood of voting in the first place. In an as-yet unpublished study, [John] Hibbing has found that people with high levels of the stress hormone cortisol are much less likely to vote than are demographically similar people who have lower cortisol levels.

Hormones again — but even here, they only influence the voter. A supporter of her proposition might argue that influences could potentially be overcome with rational arguments. Buchen ends on a conciliatory note, suggesting that the studies might help people:

[John] Alford says that the biggest impact of all this research may be to make political discourse more civil and accepting of differences. “It would be nice if political science made dinner tables a little more humane,” he says.

Notice that she spelled it “nice,” not N.I.C.E. (In his novel That Hideous Strength, N.I.C.E. was Lewis’s wonderfully named dystopic vision of a scientific oligarchy run amok, the National Institute for Coordinated Experiments.)
Buchen does not suggest that a scientific elite should take the knowledge of biological influences on politics and use it to forge a new political science. She even makese value judgments on what would be “nice” and “humane.” So far so good. But why, then, even conduct experiments on humans to find biological influences on their rationality?
We know that history’s most destructive ideologies sometimes started with good intentions (eugenics being a prime example). If scientists after World War II were rightly wary about experiments that explored genetic differences between people, why give good press to those who run such experiments today? Scientists might well want to understand genetic and biological differences between athletes, but seeking to reduce people’s ideology to biology runs the risk of supporting a scientific oligarchy that Lewis feared would lead to the Abolition of Man.
It’s time to run Buchen’s analysis through the “argument from reason” test. She wisely gives herself some outs: biology might shape political beliefs, not determine them; the biological influences might be too complex for science to figure out. She provides a tip-off to her own ideological perspective, however, in this sentence about early qualms against genetic experiments:

Modern politics seemed too divorced from basic human biology, too recent an innovation in human evolutionary history, to be influenced by genetic material.

The fact that Buchen goes on to describe experiments in a favorable light that did (at least partly) show biological influence on reason leaves the reader with the feeling that biological determinism may, some day, be established by scientists. “Many of the hormone studies done so far have come under attack, because they often rely on small samples and the reported effects are sometimes weak.” That phrase “so far” suggests she believes confirmation of biological determinism lies in the future with continued experimentation. Remember how she quoted Hibbing: “We tend to think [political beliefs are] the result of some rational responses to the world around us.” But in fact…. she responded.
Furthermore, Buchen never defends the proposition that people choose their beliefs through rational arguments.
For these reasons, her article fails the test. If Buchen and the editors of Nature believe that biology is capable in principle of explaining our rationality, then there is no reason to believe that biology explains anything — including the proposition that our reason arose from biology. We encourage readers to run this test on the next materialist argument they encounter. For further insights, read The Magician’s Twin.