What happened between 1900 and 1939 to diminish the "culture of progress" in the West?
The main things that happened to diminish the culture of progress in the West in this time period were World War I and the Great Depression.
The culture of progress was a thing of the late 1800s. The time period from 1870 to 1914 is sometimes called the “Age of Progress.” This was a time when science and scientific thinking seemed to be making life better for everyone. People thought that this could continue indefinitely.
But this illusion of constant progress was shattered in 1914. This was when World War I broke out. The war showed that, regardless of how much progress had been made, human beings could still act in horrible ways. The war also showed that science and technology could be used for violence and cruelty, not just as tools of human progress. This made it clear that progress would not be perpetual.
The Great Depression then further deflated the idea of a culture of progress. It showed that modern ways could not prevent economic catastrophe from occurring. The Great Depression also brought about such things as the rise of fascism, most particularly in Germany and Italy. This further illustrated the fact that progress would not be constant.