So, now replying knowing your context, this actually came up in discussion with Eliezer at the dinner after his talk at MIT. The most agreed upon counterexample was more restrictive drug laws. But if one interprets Eliezer's statement as being slightly more poetic and allowing that occasional slips do occur but that the general trend is uni-directional, that looks much more plausible. And the opinion of the general American population in 1850 in many ways doesn't enter into that: most of that population took for granted factually incorrect statements about the universe that we can confidently say are wrong (e.g. not just religious belief but belief in a literal global flood and many other aspects of the Abrahamic religions which are demonstrably false).