The first way in which stifling debate around taboo topics can do harm is by holding our morals hostage to the facts. By equating particular scientific statements (e.g., “the difference in mean IQ between European Americans and African Americans may be partly genetic”) with racism (e.g., “African Americans are genetically inferior to European Americans”), those seeking to stifle debate commit the moralistic fallacy of concluding that a statement cannot be true if it has unpleasant moral implications (Davis, 1978)Footnote 4. And in doing so, they make a rather perverse assumption, namely that if the relevant scientific statements were ever shown to be true, then the unpleasant moral implications would be valid. Yet as Pinker (2002; Ch. 6) notes, “We should not concede that any foreseeable discovery about humans could have such horrible implications… political equality is a moral stance, not an empirical hypothesis”.Footnote 5

Indeed, there is already substantial evidence that individuals differ from one another with respect to IQ at least partly for genetic reasons (Plomin and Deary, 2015; Sniekers et al., 2017; Hill et al., 2018). But of course, this does not justify oppression or exploitation of those who have lower IQs. Likewise, there is already substantial evidence that human populations differ from one another with respect to traits like height, weight, bone density, muscle fibre distribution, lactose tolerance, thermogenic capacity and resistance to disease at least partly for genetic reasons (Epstein, 2014; Winegard et al., 2017). Yet, once again, this does not justify oppression or exploitation of populations who have lower means on these traits. Note that it is not being asserted that a genetic contribution to racial gaps in IQ has been conclusively demonstrated, but rather that such a finding would not have a qualitatively different epistemological status from the recent finding that, say, genes associated with increased heightFootnote 6 are elevated in Northern Europeans relative to Southern Europeans (Turchin et al., 2012; Robinson et al., 2015).

The point that we should not hold our morals hostage to the facts has been made over and over again by scholars interested in race, genes and IQ. For example, Wilson (1978) stated,

Given that humankind is a biological species, it should come as no shock to find that populations are to some extent genetically diverse in the physical and mental properties underlying social behaviour. A discovery of this nature does not vitiate the ideals of Western civilisation. We are not compelled to believe in biological uniformity in order to affirm human freedom and dignity

Similarly, Jensen (1972) stated,

We must clearly distinguish between research on racial differences and racism. Racism implies hate or aversion and aims at denying equal rights and opportunities to persons because of their racial origin… But to fear research on genetic differences in abilities is, in a sense, to grant the racist’s assumption: that if it should be established beyond reasonable doubt that there are biologically or genetically conditioned differences in mental abilities among individuals or groups, then we are justified in oppressing or exploiting those who are most limited in genetic endowment. This is, of course, a complete non sequitur

Herrnstein and Murray (1994, Ch. 13) stated,

Nothing seems more fearsome to many commentators than the possibility that ethnic and race differences have any genetic component at all. This belief is a fundamental error. Even if the differences between races were entirely genetic (which they are surely not), it should make no practical differences in how individuals deal with each other. The real danger is that the elite wisdom on ethnic differences––that such differences cannot exist––will shift to opposite and equally unjustified extremes. Open and informed discussion is the one certain way to protect society from the dangers of one extreme view or the other

As far back as the 1960s, one of the founding fathers of the ‘modern synthesis’ Ernst Mayr (1963) stated,

Equality in spite of evident non-identity is a somewhat sophisticated concept and requires a moral stature of which many individuals seem to be incapable. They rather deny human variability and equate equality with identity. Or they claim that the human species is exceptional in the organic world in that only morphological characters are controlled by genes and all other traits of the mind or character are due to “conditioning” or other non-genetic factors… An ideology based on such obviously wrong premises can only lead to disaster. Its championship of human equality is based on a claim of identity. As soon as it is proved that the latter does not exist, the support of equality is likewise lost

And in a recent New York Times op-ed, geneticist David Reich (2017) stated,

I am worried that well-meaning people who deny the possibility of substantial biological differences among human populations are digging themselves into an indefensible position, one that will not survive the onslaught of science. I am also worried that whatever discoveries are made — and we truly have no idea yet what they will be — will be cited as “scientific proof” that racist prejudices and agendas have been correct all along, and that those well-meaning people will not understand the science well enough to push back against these claims.

As the quotes from Jensen, Mayr and Reich hint at, equating particular scientific statements with racism is not merely logically fallacious, but potentially unethical too. The reason being that it may end up encouraging precisely the behaviour that it aims to forestall. Suppose for the sake of argument that, one day in the future, evidence for a genetic contribution to psychological differences between human populations becomes so overwhelming that it cannot be reasonably denied. Note that there is nothing in science which rules this possibility out (Flynn, 2017). If between now and then, anyone who claims that genes might contribute to psychological group differences is pilloried as a ‘racist’, when the evidence eventually does become overwhelming, a much greater number of people are likely to take it as “scientific proof that racism was right all along”. By contrast, if instead it is continuously asserted that “political equality is a moral stance, not an empirical hypothesis”––to quote Pinker once again––there is arguably much less danger of any discovery being taken as “scientific proof of racism”.

The distinction between facts on the one hand, and values on the other, goes back at least to David Hume (1739; Bk. 3, Pt. 1), who demonstrated that propositions about what ought to be the case cannot be derived from propositions about what is the case (and see Moore, 1903, Ch. 1). In other words, no normative conclusion is implied by any positive proposition except in conjunction with an auxiliary normative proposition. For example, take the normative conclusion “whites are justified in oppressing and exploiting blacks”. There is no pair of positive propositions from which this conclusion can be validly deduced. For example, the argument “blacks have a lower mean IQ than whites; therefore whites are justified in oppressing and exploiting blacks” is obviously invalid. Indeed, it is not even a syllogism. The conclusion “whites are justified in oppressing and exploiting blacks” can only be derived from the premise “blacks have a lower mean IQ than whites” in conjunction with another normative proposition, namely that “races with higher average IQs are justified in oppressing or exploiting races with lower average IQs”. And there is of course no scientific evidence that could be adduced in support of that proposition. To summarise, particular scientific findings (e.g., that variation in IQ is partly genetic) are logically independent of particular normative conclusions (e.g., that people should not be exploited).

One possible objection to the preceding argument goes as follows. The discovery of a genetic contribution to, say, race differences in crime rates would seem to provide a strong Bayesian rationale for policies like racial profiling (e.g., stopping and searching black youths more often than white youths), which many people believe are unethical (see Risse and Zeckhauser, 2004; Sesardić, 2018). Insofar as this is the case, can it really be said that scientific findings are logically independent of normative conclusions? Taking ‘independent’ to mean ‘not logically deducible from’, yes it can. Just because something is ‘rational’ does not mean it is necessarily ethical. Indeed, discriminating on the basis of group differences is ‘rational’ regardless of whether those differences are genetic or environmental in origin, so the fact that racial profiling has already been criticised (i.e., has been criticised in a context where race differences in crime rates are almost universally assumed to be environmental) illustrates that many people accept the principle that something can be unethical even when it is ‘rational’. Another point worth making is that racial profiling is fundamentally different from the kinds of oppression and exploitation that were meted out by racists in the past. As Sesardić (2018) notes, the police already profile men (who are much more likely to commit crime than women), but most people do not see any problem with this. Moreover, several black scholars have pointed out that the primary beneficiaries of racial profiling are the law-abiding black people who live in the neighbourhoods where black criminals operate (e.g., Riley, 2015, Ch. 3; Williams, 2017).

Furthermore, some radical political philosophies such as ‘luck egalitarianism’ are arguably just as easy to reconcile with the findings of differential psychology and behavioural genetics as any ‘elitist’ political philosophy (Dworkin, 1981a,b; Cohen, 1989; Anderson, 1999; Knight, 2013).Footnote 7 For example, the philosopher Ronald Dworkin (1981a,b) drew a distinction between ‘tastes and ambitions’ on the one hand and ‘endowments’ on the other (see Lamont and Favor, 2017). An individual’s tastes and ambitions comprise all the choices he makes that affect his material well-being, such as how hard to work, and whether to spend money frivolously or prudently. By contrast, his ‘endowments’ comprise all the handicaps or advantages he possesses due to circumstances beyond his control, such as his genes, his family’s wealth or simple bad luck (e.g., getting hit by a car). According to Dworkin, material inequalities that arise due to differences in ‘tastes and ambitions’ may be justified, but those that arise due to differences in ‘endowments’ are not. So even if IQ were 100% genetic (which incidentally, it is not), since individuals cannot control the genes they will inherit, there is a relatively strong case to be made that inequalities arising due to differences in IQ (whether between individuals, classes or races) should be reduced or eliminated. Of course, this is not to say that luck egalitarianism is the correct moral theory, but simply that the findings of differential psychology and behavioural genetics need not be inconsistent with left-wing political ideals (see Dillow 2018).