https://www.youtube.com/watch?v=-BGbHG63x8w&index=220&list=PLoCQGed4XD0PlrmXM7NIVKEDl4tRAnEam&t=0s

steven hicks in his youtube vid on postmodernism 

says (I vastly over simplify)

1. pre modernist times – we knew things because God told us
2. modernism – we know things because we can use our reason and scientific method
3. 3. postmodernism  we cannot know anything