It's amazing that you're the one saying that "average" people cannot, in principle, understand some things, yet you're calling me arrogant. What you're saying is absurd. It's a matter of interest, pure and simple. IQ is testing for very specific things, and those who are interested in those types of things, language, math, patterns, etc, score higher. Those who aren't interested in those things score lower, and tend to always score lower because they never become interested enough to learn them. Rarely is someone truly passionate about mathematics but unable to learn it because of some fundamental limitation. The only people that applies to are those who are cognitively limited in severe ways that prevent them from learning. The fact is, people you so easily dismiss as being innately stupid, just aren't interested in intellectual pursuits, which unfortunately is extremely common in our civilization. Even those with slight cognitive disabilities could get a PhD at MIT if they were extremely interested in doing so, and had the lifespan it would take to learn it at their much slower pace. Most people like that aren't interested at all in intellectual pursuits, because of culture, but also because, with it taking so much longer to learn things, it's just not fun.