This disregard of human authority may have two roots.
It may spring from the belief that human history is a simple, unilinear movement from worse to better - what is called a belief in Progress - so that any given generation is always in all respects wiser than all previous generations.

To those who believe thus, our ancestors are superseded in the claim that the whole world was wrong until the day before yesterday and now has suddenly become right.
-CS Lewis, Why I Am Not a Pacifist