As a science educator I recognise the need for evidence-based reasoning and am concerned that many people are unable to tell the difference between fact, opinion and absolute rubbish.
A claim that something is true must be supported by evidence. Otherwise it is worthless.
Not everyone recognises that real evidence is hard-won through data gathering and interpretation, not based on a single instance or opinion.
Even when we are in possession of strong evidence, we then need to incorporate that knowledge into our view of the world.
We all approach an issue with a set of beliefs and values. If we are presented with new evidence that conflicts with firmly-held beliefs, we are often more likely to reject the new information and cherry-pick a few ‘other facts’ to support our beliefs.
This ‘confirmation bias’ is a major barrier to changing our mind in the light of new evidence.