Denialism is a mechanism which people or organisations employ in order to avoid inconvenient or uncomfortable truths.
It refers to the choice of 'denying reality' in order to champion a claim or theory.
One of the most well-known examples of denialism concerns the assertion that the extermination of Jews (see Holocaust denial) during the second world war never in fact happened.
Another example is the ex-President of South Africa, Thabo Mbeki, who argued against the scientific consensus that HIV caused AIDS. This led to policies preventing thousands of HIV positive mothers in South Africa from receiving anti-retrovirals. It's estimated these policies led to the loss of more than 330,000 lives.
The 5 most common characteristics of denialism
In order to assert their position and back up their claims, there are five commonly used characteristics often seen in the arguments or reasons given by those who are engaged in denialism.