Racism, science, politics, and revisionism.
And here's what he wrote later in his op-ed:
We do not yet adequately understand the way in which the different environments in the world have selected over time the genes which determine our capacity to do different things. The overwhelming desire of society today is to assume that equal powers of reason are a universal heritage of humanity. It may well be. But simply wanting this to be the case is not enough. This is not science.
Geographically separated in their evolution. Different environments in the world have selected over time the genes which determine our capacity. How much more genetic can you get?
The hypothesis of intellectual inferiority through separate evolution may be totally wrong. I hope my race's average intelligence isn't inferior. I hope nobody else's is, either. But at least it's a hypothesis. You can test IQ and other traits among populations. You can look for genetic similarities and differences. You can check geographically distinctive genes for relationships to intelligence. You can examine the extent to which "race" correlates with patterns of DNA. You can look for non-genetic causes of gaps in test performance. A lot of this research is already being done.
Watson's revisions don't contradict the hypothesis. They offer no evidence or theory to explain why it might be wrong. All they do is fudge its implications.
Now Watson says it was his idea to retire, never mind that his lab had already suspended him. He says it's time to leave because he's "closer now to 80 than 79," as though it weren't obvious that a guy who's still working at 79 but thinks 80 is a more suitable retirement age has been holding out for his birthday. Fudge, fudge, fudge.
Well, if he wants to paper over his bruised ego, that's his business. But racism, genetics, culture, black America, and the future of Africa are too important to be papered over.
It's clear from Watson's revisionism, reticence, and retirement that he wants to make his hypothesis go away. But wanting it isn't enough. That's not science. It's politics.
Will Saletan covers science, technology, and politics for Slate and says a lot of things that get him in trouble.
Photograph of James Watson by Odd Andersen/AFP/Getty Images.