Watch Bryan Magee refute Boris Johnson in 1978

Only you can't watch him because, unlike almost all of the dialogues in Magee's 1978 series Men of Ideas, the one on moral philosophy with R.M. Hare does not seem to have found its way to Youtube. So you will have to read Magee's refutation instead.

Magee and Hare were discussing the independence of facts and values. They agreed that no set of facts could logically imply a particular value.

The example Magee gave was what would follow if scientists were one day to prove that some races have higher intelligence than others - something that he and Hare, as Western liberals of their era, hoped would not happen.

Magee said:

But, at the same time, no particular social policy would necessarily follow from this fact. Some people might say: "Well, if this group is born less intelligent than that, society need devote less of its resources to educating it." But others might with equal justification say: "On the contrary, if they are born less intelligent society needs to devote more of its resources to educating them." 

It would, in other words, be entirely open to people what policy decision they were led to by the same fact.

Boris Johnson tries to get over this important point by using words like "species" to give his arguments a spurious appearance of science. But as Stumbling and Mumbling shows, he has misunderstood how IQ is calculated.

So Johnson's appeal to IQ to justify his preferred, deeply unequal, social order. And he wants to be careful: Sir Keith Joseph destroyed his prospects of leading the Conservatives with a speech with more than a whiff of eugenics - "The balance of our population, our human stock is threatened."