Two Logical Fallacies That We Must Avoid - What Is Evolutionary Psychology?

The Intelligence Paradox: Why the Intelligent Choice Isn't Always the Smart One - Satoshi Kanazawa 2012

Two Logical Fallacies That We Must Avoid
What Is Evolutionary Psychology?

In any discussion of evolutionary psychology, or human sciences in general, it is very important to avoid two logical fallacies. They are called the naturalistic fallacy and the moralistic fallacy.

The naturalistic fallacy, which was coined by the English philosopher George Edward Moore14 in the early 20th century, though first identified much earlier by the Scottish philosopher David Hume,15 is the leap from is to ought—that is, the tendency to believe that what is natural is good; that what is, ought to be. For example, one might commit the error of the naturalistic fallacy and say, “Because different groups of people are genetically different and endowed with different innate abilities and talents, they ought to be treated differently.”

The moralistic fallacy, coined by the Harvard microbiologist Bernard Davis16 in the 1970s, is the opposite of the naturalistic fallacy. It refers to the leap from ought to is, the claim that the way things ought to be is the way they are. This is the tendency to believe that what is good is natural; that what ought to be, is. For example, one might commit the error of the moralistic fallacy and say, “Because everybody ought to be treated equally, there are no innate genetic differences between groups of people.” The science writer extraordinaire Matt Ridley calls it the reverse naturalistic fallacy.17

Both are logical fallacies, and they get in the way of progress in science in general, and in evolutionary psychology in particular. However, as Ridley astutely points out, political conservatives are more likely to commit the naturalistic fallacy (“Nature designed men to be competitive and women to be nurturing, so women ought to stay home to take care of the children and leave business and politics to men.”), while political liberals are equally likely to commit the moralistic fallacy (“The Western liberal democratic principles hold that men and women ought to be treated equally under the law, and therefore men and women are biologically identical and any study that demonstrates otherwise is a priori false.”). The evolutionary psychologist Robert O. Kurzban concisely captures the common attitude among political liberals when he quips, “It's only ’good science’ if the message is politically correct.”18

Since academics, and social scientists in particular, are overwhelmingly left-wing liberals, the moralistic fallacy has been a much greater problem in academic discussions of evolutionary psychology than the naturalistic fallacy. Most academics are above committing the naturalistic fallacy, but they are not above committing the moralistic fallacy. The social scientists’ stubborn refusal to accept sex and race differences in behavior, temperament, and cognitive abilities, and their tendency to be blind to the empirical reality of stereotypes, reflect their moralistic fallacy driven by their liberal political convictions.

The left-wing denial of certain inconvenient empirical truths culminates in the wholesale postmodern denial of scientific objectivity and the concept (and possibility) of scientific truth. Conservatives too deny some empirical truths, like evolution, but they do not deny that there is such a thing as a scientific truth. But, once again, we do not have to worry about conservatives in academia, because there are very few of them (and you will find out why in Chapter 5). There are virtually no creationists who deny evolution among the faculties of American universities, but there are many, many postmodernists who deny scientific objectivity.

It is actually very easy to avoid both fallacies—both leaps of logic—by simply never talking about what ought to be at all and only talking about what is. It is not possible to commit either the naturalistic or the moralistic fallacy if scientists never talk about ought. Scientists, by which I mean basic scientists, not applied scientists like engineers and physicians, do not draw moral conclusions and implications from the empirical observations they make, and they are not guided in their observations by moral and political principles. Real scientists—basic scientists—only care about what is, and do not at all care about what ought to be. In this book, I will only talk about what is, and will never talk about what ought to be.

What Does “Natural” Mean?

It is always important in any discussion of science to avoid the naturalistic and moralistic fallacies, but it is particularly important to remember not to be tempted by them when you read this book. From a purely biological perspective, natural only means “that for which the organism is evolutionarily designed” and unnatural only means “that for which the organism is not evolutionarily designed.” The only organisms that I will talk about in this book are humans. From a purely scientific perspective, murder19 and rape20 are completely natural for humans, and getting a Ph.D. in evolutionary psychology is completely unnatural (which is partly why intelligent people do it!). Natural decidedly does not mean good, valuable, or desirable, and unnatural decidedly does not mean their opposites. One of the consistent themes in this book is that intelligent people often do unnatural things.

There are only two legitimate criteria by which to evaluate scientific ideas and theories: logic and evidence. Accordingly, you may justifiably criticize evolutionary psychological theories (or any other theories in science) if they are logically inconsistent within themselves or if there is credible scientific evidence against them. As a scientist, as the Scientific Fundamentalist,21 I take all such criticisms seriously. However, you may not criticize scientific theories, whether mine or otherwise, simply because their implications are immoral, ugly, contrary to our ideals, or offensive to some or all. I can tell you right now that the implications of many of the scientific ideas and theories discussed in this book, whether mine or otherwise, are indeed immoral, ugly, contrary to our ideals, or offensive to some group of people. They are very offensive to me. But it doesn't matter.

The truth is the only guiding principle in science, and it is the most important thing for all scientists. In fact, it is the only important thing; nothing else matters in science besides the truth. However, I also believe that any solution to a social problem must start with the correct assessment of the problem itself and its possible causes. We can never devise a correct solution to a problem if we don't know what its ultimate causes are. So the true observations are important foundations of both basic science and social policy, if you do care about solving social problems, which of course I don’t.

If what I say is wrong (because it is illogical or lacks credible scientific evidence), if it is not true, then it is my problem. It is my job as a scientist then to construct better theories or collect more evidence. In contrast, if what I say offends you, it is your problem. My credo as a scientist, which undergirds my scientific fundamentalism, is “If the truth offends people, it is our job as scientists to offend them.”22 As a scientist, as the Scientific Fundamentalist, I don't care if people live or die. I just want to know why.


[1]. In this chapter, I will briefly introduce you to the field of evolutionary psychology. For a more comprehensive introduction, I (prejudicially) recommend that you turn to my earlier book Why Beautiful People Have More Daughters (Miller and Kanazawa, 2007), which is a comprehensive introduction to the entire field of evolutionary psychology written for a general, nonacademic audience. It's not only about why beautiful people have more daughters. You may also consult any of the other popular general introductions to the field, such as Matt Ridley's The Red Queen (1993), Robert Wright's The Moral Animal (1994), David M. Buss's The Evolution of Desire (1994), and Steven Pinker's The Blank Slate (2002)

2. Dunbar (1992)

3. Wilson (1975)

4. Barkow, Cosmides and Tooby (1992)

5. Betzig (1997a)

[6]. Culture: McGrew (1998), Wrangham et al. (1994); language: Reiss and McCowan (1993); Savage-Rumbaugh and Lewin (1994); tool use: van Lawick-Goodall (1964, 1968); consciousness: Gallup (1970); Plotnik, de Waal and Reiss (2006); Reiss and Marino (2001); morality: Brosnan and de Waal (2003); sympathy and compassion: de Waal (1996); romantic love: Leighton (1987); Smuts (1985); homosexuality: de Waal (1995); Bagemihl (2000); murder: Goodall (1986); Wrangham and Peterson (1996); rape: Thornhill (1980); Thornhill and Palmer (2000); Wrangham and Peterson (1996, pp. 132—143)

7. van den Berghe (1990, p. 428)

8. Campbell (1999, p. 243)

9. de Waal (1996); Brosnan and de Waal (2003)

10. Pinker (2002)

11. Endorsement on the cover of Betzig (1997b)

12. Ridley (1999, pp. 256—258)

13. Ellis (1996)

14. Moore (1903)

15. Hume (1739)

16. Davis (1978)

17. Ridley (1996, pp. 256—258)


19. Buss (2005)

20. Thornhill and Palmer (2000); Thornhill and Thornhill (1983)


22. Kanazawa (2006a).