How did the beat movement criticize mainstream culture?

The Beat Generation was never a large movement in terms of sheer numbers, but in influence and cultural status they were more visible than any other competing aesthetic. The years immediately after the Second World War saw a wholesale reappraisal of the conventional structures of society. Just as the postwar economic boom was taking hold, students in universities were beginning to question the rampant materialism of their society. They saw runaway capitalism as destructive to the human spirit and antithetical to social equality.

Democracy and darwinism would be my answer.