Thank you.
Yes, that was what I was thinking of – with there having been a period of real, if mistaken, settled science – in starting the thread.
Before doing any research, I recalled that there was a consensus regarding peptic ulcers being caused by stress, replaced in the 1980’s with the cause being a bacterial infection.
But these two links show my memory of there being an old-time consensus on the cause of peptic ulcers was mistaken: