[salmonellaeater]

I think his definition of progress is steady change toward an ideal version of humanity. The main problem is that the ideal changes with the age, and not in a predictable way. If you were to ask someone 500 years ago what a perfect person was, it would be quite different from the answer you'd get today. What does progress even mean if the ideal towards which humanity is moving keeps changing? It just becomes a random walk.

Also, just because human behavior is changing, doesn't mean human morality is becoming better in any objective sense.

[jonathanwallace]

The phrase "random walk" immediately makes me think of evolution. :)