I used to naively think that intelligence and stupidity are opposites, but have come to understand that stupidity is in some sense orthogonal to intelligence. Stupidity was defined by Carlo Cipolla as a personal trait, causing loss for others without gains to themselves. Stupidity is independent of any other trait or characteristics, and underestimated in many different ways. Stupidity and intelligence can according to this definition be placed in opposite corners of a two dimensional graph, where you have benefit to self on the x axis and benefit to others on the y axis. Intelligent people are hence defined as producing benefit both to self and others, where stupid people cause negative benefit both to self and others. To complete the definition you can also be classified as helpless (benefit to others, but not self) or as a bandit (benefit to self, but not others).
In an organisational setting stupidity takes on additional dimensions as described by Mats Alvesson at Lund University. He defines functional stupidity as people doing exactly what is expected of them without consideration or thought. The person does everything according to what is expected without affecting any real progress. When likeminded people who conform to current practice are more commonly promoted we end up with stupidity gathering at the higher levels of organisations.
More intelligent people are not immune to stupidity. Some traits of intelligent people have even been shown to cause stupid behaviour. More intelligent people seems to be more prone to explain away facts that are against their own beliefs. Schools and educational institutions give better opportunities to people with high intelligence. As intelligence seems to have cultural and environmental causes there exist some form of inequality that perpetuates in this system.
The level of intelligence, at least as measured by IQ tests, have increased steadily over the years in the population, and is expected to continue to increase over time. This is what is called the Flynn effect after the researcher James Flynn. For some populations in highly educated countries the level of intelligence has been found to decline now lately. According to Flynn himself this is caused by the level of intelligence reaching a limit. The increase in intelligence seems likely due to cultural and environmental effects. The decline could presumably also be due to change in culture or environment. Spreading misinformation and closing libraries are examples of things that can have an effect. Intelligent people promoting activities like this is most disturbing but not entirely unexpected. As competition for prestigious positions increase it is easy to see how privileged groups could opt for interventions that reduce competition. There can however also exist less visible effects lowering the level of intelligence in a population that is built in due to a lack of knowledge. The school system with an excessive focus on learning toward a specific objective and a loss of motivation of students may hence also contribute to this effect.
We urgently need to counteract all kinds of stupidity. This can be done by encouraging curiosity, learning and questioning. Striving for more intelligence in itself is probably not the solution. The question is what we as a society wants. Im not certain that striving for increased intelligence is wise. There should be more discussion and debate on targets and effects of our school system and what is promoted in our society.
For those of you who know Swedish i would once again recommend listening to P3 Dystopia, especially the episode named "Dumhet" that can be found at https://sverigesradio.se/avsnitt/dumhet-p3-dystopia. The material they used for research can be found at https://sverigesradio.se/ with references partly in English.
