For science, denialism is the rejection of the incontestable. The denialist refuses to believe in a scientifically proven reality and in consensuses obtained through in-depth studies. An example of scientific denialism is misinformation or boycotting a medical treatment or a vaccination against some kind of virus or bacteria.

For history, denialism is denying or distorting the  historical records of our humanity. I highlight here some examples of historical denialism such as the denial of the Holocaust and so many other  war crimes. In today's world many denialist ideologies use  the internet to spread throughout planet Earth, they use the media as a vehicle in order to reach a greater number of people and thus spread their denialist concepts.

What is the difference between pessimism and negationism?

There is a lot of confusion about the relationship between pessimism and denialism, so we can better understand these types of thoughts and behaviors. Pessimism usually arises in situations where certain risks are involved, from our health to our economic situation, where people feel very worried about how they are going to move forward and so "fear" sets in, which often paralyzes us.Denial can arise in an attempt to face the "fear" and so we deny the facts so that perhaps we won't suffer further or will suffer less.But we have to understand that denying facts, situations or certain results will not solve our fears or problems, because at some point in our lives our fears will have to be faced. Much has been said about resilience, but little has been understood and applied because of the fear of facing obstacles.

But what does it mean to be a resilient person?

Being resilient means adapting to change, overcoming difficulties and fears and knowing that we have the capacity to deal with problems head on and to move on with our lives, focusing on solutions and not only on obstacles. Denialism is a very broad subject that needs to be discussed safely so that it doesn't get confused with other types of ideologies and behaviors.