When you repeat a falsehood often enough, people will eventually believe it is true. This is a scientifically tested observation, called the illusory truth effect.
The simpler the “fact,” the more likely it is perceived to be true. Of course, your predisposition towards a piece of information also plays an important role to whether we take it as truthful or not.
But even if you doubt a certain statement initially, the longer and the more you are repeatedly exposed to it, the more likely you will believe it.
Best current example is the viral sharing of fake news on social media. Other examples of widely accepted false truths are that the intake correlates with the risk of heart disease, that Vitamin C always helps against the common cold, or that spinach is incredibly rich in iron.
These widespread false beliefs may originate from an actual error or in most cases from an incorrect interpretation of accurate facts. In a game of telephone of repeated citations and sub-citations, statements are then more and more simplified until they reach equal peak simplicity and believability.
The shocker for me was reading that knowledge does not protect against illusory truth.
A very 1984-esque situation, isn’t it? We can create truth through repetition even in the face of better knowledge.
Truth becomes what the majority believes.