Recently I came across this quote:
“When you are dead, you don’t know that you are dead.It is difficult only for the others… It is the same when you are stupid.” 
Isn’t this the best quote ever?
At times when people are voting for Donald Trump, enormous corruption scandals are being unveiled, terrorist attacks are becoming the norm as well as bombarding others’ countries, we all have something to say about stupid people. As unbelievably stupid as others may seem, we need to keep in mind a couple of things:
1. We might appear equally stupid for others as well, and;
2. In the end, we are all just people.
For the sake of not appearing stupid and for reducing the general level of stupidity in the world, let’s try to understand how this happens. Fortunately I am not the first one to ask this question, and much more competent people have studied this before. We should learn from them. In 1999, David Dunning and Justing Kruger ran a series of experiments to test how people assess their own competence at a task. This was inspired by a very interesting fact:
“The study was inspired by the case of McArthur Wheeler, a man who robbed two banks after covering his face with lemon juice in the mistaken belief that, because lemon juice is usable as invisible ink, it would prevent his face from being recorded on surveillance cameras.”
I know… I know… How in the world can a person think that lemon juice would make their face invisible on cameras? And if they thought so, why haven’t they tested it *before* robbing a bank? It turns out that the lack of competence is so big, but so big, that they are unable to doubt their reasoning and think for a second that they might be wrong.
Now, this is an extreme case, of course, but the study has shown that incompetent people were often over confident, and guessed a much higher score than they actualy got. This is known as the Dunning-Kruger effect.
At this point you might be thinking: “Sure, but I am not a stupid person.”
Aren’t you? Think again. If a stupid person is not able to assess their own stupidity, how do you know you are not one of them?  How do I know *I* am not one of them? No one wants to be seen as stupid by other people, so we should really find out.
The Dunning-Kruger effect is observed when unskilled persons have what is called “illusory superiority”. The name is self-explanatory. It is also known as the above average effect (e.g. in a survey, 87% of MBA students at Stanford University rated their performance above the median — something which is mathematically impossible). How can we avoid the self-inflated judgement of ourselves? This being a cognitive bias, it is virtually impossible to get rid of 100% in practice. Nevertheless, I believe there are some things we can do to alleviate it:
Whenever you think you know about something, google it. But don’t just take the first link, google also makes mistakes and the results of searches are biased. Make sure the sources you are checking are reliable, and be aware how far your knowledge goes. Inform yourself, check the facts and make sure you are not over simplifying (or maybe complicating!) things. (That is healthy doubting. We do not want the kind of unhealthy doubting that makes us crawl underneath the covers and feel bad about ourselves!)
Challenge your beliefs
It can be very healthy to talk to people that disagree with you, if they are equaly engaged and willing to explain their point (and not ofended by your questions ). It is good to understand the other side’s reasoning that led them to a different conclusion than yours, and it is good to explain your reasoning to others. Explaining is a very nice way to sanity-check your reasoning.
Learn from experience
If you are in a situation that others have been before, take a look at the past experiences. How are they similar to what you are going through? How are they different? What actions were taken? What was the outcome? Has someone conducted scientific studies on this before? Learn something from them.
Don’t let emotions get in the way
When someone says we are wrong, our first reaction is to listen to the “you are wrong” part and ignore completely why they think we are wrong. We are humans and we don’t like being wrong, but the moment we start being defensive is the moment emotion takes over reasoning. And emotions tend to make us even more biased. So if you feel your heart beating harder when you listen to something, take a step back, breath, and think coldly what exactly it was that made you startle. You might even learn a thing or two about yourself.
Give information instead of opinions
When you think someone is being stupid about something, give them some information they can reflect on. If they even think you implied they are wrong, they will stop listening to you. If you have ever changed your mind, you know that this is not a straightforward procedure. It takes time and it has to come from within. The best you can do is provide more information so the person can think for themselves.
Good luck and stay wise!
 Possibly attributed to Philippe Geluck, but I could not check with absolute certainty.
 I am not saying you will put lemon juice on your face and rob a bank. Please don’t be angry. I am not calling anyone stupid.
 This happens more often than not, unfortunately.