Answer:
Due to first world war.
Explanation:
Hauser stated that in the first decades of the 20th century there is a climate of disruptive times and cultural pessimism, the author mean in the statement that at that time life of the people of different nations are not good and they passes through a very hard times because in the first decades of the 20th century, first world war started which destroys the peace of the whole world and the people experience harsh times of their life.