Religion
In reply to the discussion: The dictionary is wrong – science can be a religion too [View all]SheilaT
(23,156 posts)That took only about 70 or so years to be accepted.
The germ theory of disease. It was several decades before doctors got on board with that. President McKinley didn't die from the gunshot wound, but from the incompetence of his doctors who didn't bother to wash their hands before poking their fingers into the wound. Women continued to die from doctor-caused infections because they saw absolutely nothing wrong with such things as performing an autopsy and then going straight to delivering a baby without handwashing. This continued for years after Semmelweiss proved conclusively that this practice was directly killing women.
I believe it was in the 1950's that it was suggested that bacteria might be a significant cause of ulcers. How silly. Everyone KNEW that ulcers were from stress and spicy foods. The bacteria causing a lot of ulcers was identified in 1982.
These are just off the top of my head. There are times science really is slow to adopt change.