This is an extraordinary claim by Eliezer Yudkowsky that progress is a ratchet that moves in only one direction. I wonder what, say, the native Americans circa 1850 thought about Western notions of progress? If you equate "power" with "progress" this claim is somewhat believable, but if you're also trying to morally characterize the arc of history then it sounds like you've descended into progressive cultism and fanaticism.