Against a dictatorship of relativism : Brave new world?

This post by Dev Thakur includes:

It reminds me of Pavel Chichikov's two-sentence formula to sum up all of human history (oft-quoted by Mark Shea):

1. What could it hurt?

2. How was I supposed to know?

I don't buy that it sums up all of human history, but it sure covers a lot of it! (Especially the bad mistakes.)