Logical positivism
Logical positivism was the philosophical flavour of the day in the 1920s and 1930s, and it was indeed popularized by Ayer in his book "Language, Truth and Logic". However, Ayer himself later rejected much of his own work. Fifty years after he wrote his book, he said: "Logical Positivism died a long time ago. I don’t think much of "Language, Truth and Logic" is true. I think it is full of mistakes".