The triumphs of science have provided its practitioners with an aura of respect*. Many people would have problems describing what the job of a scientist is. However, if someone can produce some kind of “credentials”, it may automatically increase his or her credibility. This might not be entirely unreasonable but still, don’t be over-reliant on “credentials”.
We need to bear in mind that Science is a collective enterprise, not the property of individuals. What a man of science believes is not as important as how and why he believes it. Scientific knowledge is tentative, not dogmatic; based on evidence, not on authority or intuition.
Everyone is entitled to have opinions. But opinions are not knowledge, even less scientific knowledge. A thriving scientific community provides a safety mechanism and prevents science’s most pre-eminent members from single-handedly pushing unscientific agendas.
During the years, very cleaver people, excellent scientists in their fields, have had not very cleaver beliefs:
Sir Isaac Newton, co-founder of modern physics, was a keen alchemist. As an alchemist Newton tried to transform base metals into gold. It has been said that Newton’s erratic behaviour in later life could be attributed to heavy metals poisoning; there was an alchemic tradition of tasting chemicals to take note of their flavour…
Linus Pauling, winner of two Nobel Prizes, one for chemistry and one for peace, came to believe in his later years in something called “orthomolecular” medicine. He believed that almost any disease (like cancer) could be cured by providing overdoses of vitamins or other nutrients. Simple!
Fellow Nobel Prize laureate, French virologist Luc Montagnier, apparently endorses homeopathy; more specifically, that water has “memory”. Memory! Water!
The scientific community has scoff out of court these beliefs, regardless of the eminence of their supporters. This rejection is not out of narrow-mildness, on the contrary; it has rejected them because scientific knowledge is not based on authority or intuition but on evidence, and there is no evidence whatsoever supporting alchemy, orthomolecular medicine, or homeopathy (but there is a lot of evidence opposing them).
Scientists always keep an open mind but they only change that mind based on evidence: Less than a century ago scientists didn’t believe that DNA could be the carrier of hereditary information, but they gradually changed their mind based on evidence. At the beginning of the 20th century scientists didn’t believe that the brain was formed by individual neurons, but they gradually changed their mind based on evidence. Less than 10 years ago scientists didn’t believe that stem cells could be created from adult human cells, but they gradually changed their mind based on evidence.
Having acknowledged this, if I am in the middle of the Amazon, and I am bitten by a bug, I’ll pay attention to what the shaman of the village has to say. Not because I blindly trust on him but because he tends to be the most knowledgeable person around. When discussing about health or general science is advisable to pay attention to the scientist in the room. But always remember to contrast his or her opinion with that of the general scientific literature or other scientists. Then you will know whether you were provided with scientific advice or just the ridiculous opinion of a pariah or a member of a sect of lunatics.
* Even in this relativistic, postmodern, society.