Even though it’s such an easy topic, few things have been so poorly understood by laymen as the role of a consensus in science, leading to phrases like ‘a consensus is not science’.
This statement could not be any further from the truth.
But it takes some understanding of the philosophy of science to understand what is wrong with the statement. Many people seem convinced ‘consensus’ implies scientific proof is lacking. Before dealing with consensus, it’s important to understand what “scientific proof’ actually means. I’ve dealt with this issue in my post Loose thoughts on some frequent fallacies. It’s very important to understand the philosophical travesty the post tries to make clear : a ‘proof’ in the sense of an ’absolute truth until the end of time’ does not exist.
As odd as it may sound, the word proof only reflects the current state of knowledge, we are not able to prove anything. Even for theories we ‘absolutely know for sure’ they are real we don’t have any proof at all. Just assumptions (usually strengthened by conducting experiments). Take for instance the gravitation-theory. It’s merely an unproven theory !
Let’s ask a tricky question : how do you ‘prove’ gravity is not just a theory ? I’ll give you a hint : you can’t. Really, it’s impossible !
Sure, you can write down Newton’s law :
Does this law ‘prove’ gravitation ? No !
Sure every experiment you conduct will obey he law, but this doesn’t prove the equation. Not at all. It just doesn’t falsify the theory, that’s all. Conducting the experiment a zillion times does not provide any evidence or ‘proof’ next time the apple will fall from the tree too. After all, one day, who knows, the apple will not fall. The point is : science works with assumptions and predictions, but from a philosophical point of view none of these provide an absolute evidence or ‘proof’.
Nevertheless, no one in their rightful would discard gravitation. Why ? Scientific theories never ever are accepted because they are proven to be right (as we cannot proof them) but because scientists accept them. In other words, because there is a consensus.
Many people fail to understand this. While science accepts the evolution theory, there are people like Erich von Däniken saying extra-terrestrials came to earth and initiated earth’s civilisation. Why isn’t his theory accepted ? After all, we cannot prove aliens did not come to earth ? One reason is there’s a whole lot of positive assumptions supporting the evolution-theory, while there are none for the ET-theory. But as none of them really ‘prove’ anything, the simple reason evolution is accepted is a vast majority of scientists accepts the theory.
Science is –always– based on nothing more than consensus ! People who say a consensus isn’t science don’t understand science.