In previous editorials I have written about the absent-minded and socially-inept 'nutty professor' stereotype in science, and the phenomenon of 'psychological neoteny' whereby intelligent modern people (including scientists) decline to grow-up and instead remain in a state of perpetual novelty-seeking adolescence. These can be seen as specific examples of the general phenomenon of 'clever sillies' whereby intelligent people with high levels of technical ability are seen (by the majority of the rest of the population) as having foolish ideas and behaviours outside the realm of their professional expertise. In short, it has often been observed that high IQ types are lacking in 'common sense'--and especially when it comes to dealing with other human beings. General intelligence is not just a cognitive ability; it is also a cognitive disposition. So, the greater cognitive abilities of higher IQ tend also to be accompanied by a distinctive high IQ personality type including the trait of 'Openness to experience', 'enlightened' or progressive left-wing political values, and atheism. Drawing on the ideas of Kanazawa, my suggested explanation for this association between intelligence and personality is that an increasing relative level of IQ brings with it a tendency differentially to over-use general intelligence in problem-solving, and to over-ride those instinctive and spontaneous forms of evolved behaviour which could be termed common sense. Preferential use of abstract analysis is often useful when dealing with the many evolutionary novelties to be found in modernizing societies; but is not usually useful for dealing with social and psychological problems for which humans have evolved 'domain-specific' adaptive behaviours. And since evolved common sense usually produces the right answers in the social domain; this implies that, when it comes to solving social problems, the most intelligent people are more likely than those of average intelligence to have novel but silly ideas, and therefore to believe and behave maladaptively. I further suggest that this random silliness of the most intelligent people may be amplified to generate systematic wrongness when intellectuals are in addition 'advertising' their own high intelligence in the evolutionarily novel context of a modern IQ meritocracy. The cognitively-stratified context of communicating almost-exclusively with others of similar intelligence, generates opinions and behaviours among the highest IQ people which are not just lacking in common sense but perversely wrong. Hence the phenomenon of 'political correctness' (PC); whereby false and foolish ideas have come to dominate, and moralistically be enforced upon, the ruling elites of whole nations.