For example, Fukuyama says that men
“have a biological disposition to be more promiscuous and less discriminating than women in their search for sexual gratification”.
This is where Leftists commit the is/ought fallacy. Sometimes intentionally, sometimes not.) That is, when scientists (of whatever description) say that
X is the case.
that doesn't mean that they also believe that
X ought to be the case.
In fact knowing that X is the case means that you can do something about X (if society or individuals so desire). In this case, saying that men are
“more promiscuous and less discriminating than women in their search for sexual gratification”
isn't to say that this is a good or a bad thing. It's to say that it's a... thing. Not only that: this fact is true “statistically” and over “large populations” (as Fukuyama puts it). In other words, it's not true of every man who's ever existed on the planet. In addition, this isn't a denial of female promiscuity either. How could it be?
The thing is that some (perhaps the minority) of Leftists know that they're committing the is/ought fallacy when they criticise such statements. However, that doesn't matter. They believe that too many people knowing certain truths or facts (or, rather patronisingly, “misusing” certain truths or facts), is a state of affairs they simply can't allow. Thus Fukuyama and other scientists must be reprimanded, ridiculed and, in some cases, even denied tenure. Certain truths or facts are deemed to be dangerous by Leftists.
Fukuyama himself comments on this Leftist denial of truth as it can be found in sociology.
As many people know, sociology has been a largely left-wing discipline - especially since the 1960s. That doesn't need to be the case. Leftism or “progressivism” isn't (as it were) built into sociology. Nonetheless, that Leftist bias is why Fukuyama says the following:
“The more I read the more it became evident that the social sciences were operating on a principle that was ideologically based.”
This has been particularly true of biological phenomena as they're interpreted by sociologists. I mentioned male and female sexuality before: Fukuyama says that sociology took this Leftwards turn as a “reaction to the Holocaust and to the genuine misuses of biology by assorted racists and bigots”. What's more, the social sciences “had been turned in the opposite direction – to say that one's genetic basis meant nothing”.
Perhaps more importantly, Fukuyama himself interprets biology politically. (Thus it can be said that he's contradicting himself.)
For example, knowledge of biological givens
“shows you that there are certain constraints in social engineering that limit the kind of society you can create”.
Consequently, the many 20th century experiments in communism “provide a negative lesson that there are certain types of utopias that aren't realizable”.
Fukuyama, Francis. (1999) quoted in Predictions: 30 Great Minds on the Future