Female chess grandmasters are also pretty rare.
Nobody knows if there are any deep-rooted differences in intelligence between men and woman. With any such thing you would have to have quite the difference in performance to be able to confidently claim that the difference is biological.
The reason is quite simply that intelligence is product of both nature and nurture, and perfectly separating the two would require controlled experiments. You simply can't do that in humans, you can't ensure that two people are perfectly exposed to exact same influences.
So, that's why studies show some differences, but you would have to be an idiot to conclude on it. Same goes with chess. Yes, it is overwhelmingly dominated by men on a top-level, but it is also mostly played by boys. Whatever biological advantages either gender has, is masked by the amount of male players.
Another difference would be height. Since height is a product of nature and nurture, you can't tell which population is genetically taller, because the effect of especially nutrition masks the exact difference. However, we know that there is an important biological component, and we can make pretty strong assumptions based on that. For instance, in developed nations where boys and girls have the same nutrition, you clearly see a difference. Also, we can clearly see it from nation to nation. There must be something more to it than nurture, anything else would be insanely unlikely.
The ex-prof tries to conflate the argument. Yes, we can't exactly pinpoint the extremely complex factors that make a man stronger than a woman, but just like with height, we observe it in nature.
Hi is trying to argue that "if we can't describe gravity perfectly, then the natural phenomena doesn't exist". If you can't explain why something is, then it isn't.
It's so obviously retarded, and Krasnoff pointed it out for him. The natural world isn't bound by our capability to understand it. Let's say there is a difference in intelligence between woman and men, then that difference would exist even if we are able to understand it or control for it. We shouldn't follow Plato's retarded ideas anymore. Seriously, this is introduction to philosophy stuff.