Conspiracy theories and confirmation bias
In the current pandemic period, we have a flowering of all sorts of conspiracy theories, built on the top of the most popular fake news that circulates constantly in the social networks and more generally on the internet. It can happen that some of these misleading information are found on the accounts of the most important people in the world, like president of the USA D. Trump, and social media platforms are wondering if it is their responsibility to take an action to prevent the diffusion of lies ( here ), engaging a fight to determine what is true and what is not. In general this is a very difficult task. Human beings are able to look at the facts from a neutral point of view only when they are not involved in any way in the matter, and this is uncommon. For example we can be emotionally engaged in some way, often simply because we like the group of person that is saying the news, or because we think that we know the topic. Some of the more common conspiracy theories are the one with the so called "Big Pharma" and vaccines. In particular the anti-vax movement is gaining popularity in this pandemic period, contrary to the common scientific sense and without ever having a vaccine ready to use. Supporters of those theories are able to provide many proofs that their theory is correct. Often those evidences are true, but the logical issue with the theory is somewhere else.
One of the biggest problem is that it is not possible to prove that any theory is true by looking only at the facts that are not in contradiction with your thoughts. In making the decision you should also take into account the hypothesis that your theory is false, and try find some facts that prove this, or find some contradiction that allows you to take a decision on more solid grounds. Only by evaluating the probability, given the facts that you observe, that the theory is true, and then by evaluating the probability that the theory is false given the same facts, you can say something about the theory. Maybe at this point you will discover that you don't have enought information. Or that the theory is false. One must also be aware of the fact that in general, unless we are talking about a mathematical theory, we can never be absolutely sure that we are right, we can only talk about confidence and probability that something is true given the facts that we observe.
This line of reasoning, that should be at the base of the scientific method (every hypothesis should be 'falsifiable'), it is not what most of us think one should do when one wants to validate a theory. The phenomenon is called confirmation bias . It is the tendency of the human that has a theory in mind to look only for facts that supports that theory, without trying to falsify it, and neglecting or assuming that it is false anything that is in contradiction with it. This can distort reality in a conscious or an unconscious way. For example think about the avereage volleyball match. Look at the public. Have you ever noticed how biased is the the view of the supporters of each team and how is it different from the one of the referee? Often both supporter groups develop the theory that the referee is biased towards the enemy team, taking his errors as irrefutable proofs of the theory. But the theory of a biased referee is of course far less probable than the theory of a faulty referee. Nevertheless there are supporters in the public that truly think that the referee is biased.
Why is this behavior so common? Constantly looking for the truth in a consistent logical way (using the scientific method) does not need to be the best survival strategy. I'm thinking about the human beings evolution process. If testing that your hypothesis is false implicates taking a risk that can result in serious injury or death, natural selection will favor individuals that tends to look only for facts that are consistent with the theory that they have in their minds. Think for example of the theory "all lions are dangerous". No healthy person will try to falsify that theory, since the attempt can end with death. But at the circus you can find trained lions that are not dangerous, so not all the lions are dangerous (maybe if you behave in a certain way). But if you find a lion on your way, certainly you will go away without trying to falsify the theory, and it is a good idea!
The problem arises when you try to apply this natural way of thinking to facts that are not so simple, and more in general to the complex reality where we live, filled with complicate and easily accessible information. Take the example of conspiracy theories and vaccines. Everyone is able, with a simple google search, to find as much facts as he wants supporting this conspiracy theory. Damage caused by vaccines, strange correlation facts (that do not imply causality), and more. Many of those facts are true. The issue is the failure to consider the hypothesis that the conspiracy theory is false, due to the fact that the well-being of people is an important survival subject and the confirmation bias. So people tends to apply the "survival strategy", avoiding any potentially dangerous action that could falsify our hypothesis. But the knowledge about vaccines is by far vaster than the information that an average person can find on google, and the risks of distributing a well engineered vaccine to all the population are by far less than the risks associated with the absence of a vaccine.
The impossibility of knowing everything combined with the confirmation bias phenomenon are the major causes, in my opinion, of the raising of conspiracy theories in the current internet-controlled world. This is a fact that we should expect given the behavior of the average human being. At this point, we should ask our self a very important question: do we really want that our society goes forward and advances in science, so we can live better and in harmony with the Earth (and possibly the universe)? Or do we want to be simply flooded by a flux of information, taking positions that are not logical, and going against the progress of medicine and science, and stay where we are forever, or possibly going back? Hoping that the answer to the first question is positive and the one to the second is negative, we should invest in teaching the scientific method and the importance of considering all hypothesis, also those that you do not agree with, before taking a position. We should teach this more and more, in all schools of the world, building the ground for collaborations and not fights. And remember, when you are in front of a lion, do not try to see if it is not harmful.