I used to think that stupidity was the lack of IQ. But reality has shown that stupidity and IQ are completely independent variables and it is possible to have high levels of both IQ and stupidity. IQ is the ability to see patterns. A high IQ person is someone who when exposed to a pattern, can immediately grasp it while a low IQ person is someone who cannot grasp a pattern when it appears in front of them. A really high IQ person can even see a pattern when only a part of it is exposed. But this ability to see patterns has nothing to do with those patterns being right or wrong. Just because a high IQ person can see a pattern does not mean that the specific pattern is the right one. This is why high IQ people sometimes have wrong views about things. To find the right patterns is another ability that is independent of the ability to see those patterns. The lack of this ability to find the right patterns is what is called stupidity. The way to figure out which pattern is right is to question every pattern that is given to you. When you question a pattern you have to go to the underlying patterns until you get to the root where all the assumptions, facts and other patterns used to build the higher pattern become clear. But the problem is that most people just borrow patterns second hand and then build on top of them instead of questioning them and building from ground up. So a person who is able to see patterns but is in the habit of accepting them second hand is going to fall for some patterns that are wrong. An example is a pre-PMF founder trying to make the first version of their product bug free or aesthetically pleasing. Their problem is that they looked at startups after they had succeeded and saw the pattern of being bug free and good looking. This is the most common wrong pattern that people fall for when trying to do their startup. So much so that most of startup guide material is focused on trying to convince people to not fall for it. Building on top of borrowed patterns is also very tricky because you are building on a foundation that you don't know the limits of so you don't know under what conditions it does not work. And patterns once learnt are very hard to revise because you have already built on top of them and revising them would mean breaking down everything on top of them. This is why it is hard to make people unlearn things that they have been working with for too long. A person who has worked in corporate is going to spend 80% of their time doing meetings, creating presentations, and making documents pretty. This is a requirement for corporate but lethal for a startup. This is why corporate hires don't work in startups and corporates trying to do startups don't succeed. This is the same reason that most successful startups are built by people who either don't have corporate experience or were actively anti-corporate while working there. So while IQ can make you smart, it does not automatically do so. To be smart, you have to be in the habit of questioning things and then building your understanding from the ground up. People who are not skeptical often just parrot things they read or hear which is a measure for stupidity. Because lack of skepticism causes stupidity, you can find smart people by finding those who are skeptical. You can figure out if someone is skeptical by talking to them about something they're passionate about and seeing how deeply they've questioned what they're doing. The idea is not to judge people on things they have no interest in. But if they have a topic they are enthusiastic about and say things that show a lack of understanding of the underlying patterns, that means they are not in the habit of questioning things. A high IQ person who is not in the habit of questioning things is going to be stupid. Stupidity is also contagious. For smart people who are skeptical, there is still risk of stupidity if they are spending a lot of time with people who believe in wrong patterns because repeated exposure to a wrong pattern makes it seem right. P.S. By questioning things I mean questioning them in your head and not out loud. Someone who questions everything out loud is just annoying. The point to say something is when you've figured the thing out and the right thought is not being discussed. At that point, you should be the contrarian. Don't be a contrarian just for being a contrarian.