The fool thinks himself to be wise, but the wise man knows himself to be a fool.- William Shakespeare
Among many cognitive biases (apparently most people - not you of course - have ‘bias blind spot’) is The Dunning-Kruger effect which is the phenomenon whereby people who have little knowledge systematically think that they know more than others who have much more knowledge. One curious aspect you may have noticed is that they tend to become bosses. Charles Darwin knew about this illusion of confidence and said that "ignorance more frequently begets confidence than does knowledge". In Bad Science, Ben Goldacre said:
Today, scientists and doctors find themselves outnumbered and outgunned by vast armies of individuals who feel entitled to pass judgement on matters of evidence - an admirable aspiration - without troubling themselves to obtain a basic understanding of the issues.
Later he says:
I spend a lot of time talking to people who disagree with me - I would go so far as to say that it's my favourite leisure activity - and repeatedly I meet individuals who are eager to share their views on science despite the fact that they have never done an experiment. They have never tested an idea for themselves, using their own hands; or seen the results of that test, using their own eyes; and they have never thought carefully about what those results mean for the idea they are testing, using their own brain. To these people 'science' is a monolith, a mystery and an authority, rather than a method.
The arrogance of ignorance is often seen when you have a medical problem.(This is exacerbated by distrust of Big Pharma due to Marketing-Based Medicine and other machinations.) If you cut your finger and the doctor prescribes an ointment, the servant will scoff at it and say that the best cure is a paste made by crushing the roots of a particular plant. If the doctor advises 3 weeks' bed rest for a bad back, your cousin's friend (who is a brilliant Chartered Accountant you are told) will tell you with evangelical insistence about a protein drink that can cure all aches and pains within a week. Being a brilliant CA doesn't qualify you to give medical advice.The transfer of expertise from one area to another often has errors.
People who have got their medical knowledge from dumbed down news reports will speak with great confidence about cures for various problems.You will be told,"My father was given a particular piece of advice for some ailment and now I am being told something else for the same ailment. These guys don't know anything." But all errors are not equal.As the physicist Richard Feynman once wrote, science creates an “expanding frontier of ignorance” where a discovery leads to more questions which lead to more discoveries.