It's funny how it sometimes happens that the scientific or medical community makes a decision. I'm not quite sure how it happens, but once it's done, you need a

It's funny how it sometimes happens that the scientific or medical community makes a decision. I'm not quite sure how it happens, but once it's done, you need an overwhelming amount of evidence to overturn it. Much more than if the decision had never been made in the first place. Who makes these decisions, and on what grounds? I honestly don't know. Edit: But my theory is that it's based on informal groupthink.