Scientism is actually a subset of the attitude Tom Sowell has covered many times, and one I run into frequently in my line of work.
The more educated a person is, the more likely he is to assume that his expertise in field A will transfer into expertise in any field. Which is of course nonsense.
In my considerable experience doctors, lawyers and retired military officers are just about the worst in this regard.
The political expression of this attitude is the idea that lawyers and bureaucrats should be put in charge of all aspects of our society.
You are a Stockbroker ?
Hmmm, all three of these professions seem to require convincing others of you know what you are talking about. You need to trust the doctor that he knows how to heal you. You need to trust the lawyer that he knows the best legal course to take. You need to trust the military officer that his battle plan will end with the enemy rather than you and your buddies being killed.