Meanwhile in France and the French colonies in the New World, slavery was abolished by the "Enlightenment" (and "rationalist"!) French Revolution
To add a related data point, the same thing happened in the rest of Latin America. Abolition of slavery was of the first measures of many of the revolutions against the Spanish in the early 19th century, which were heavily inspired by the Enlightenment. Brazil held out a few decades more, because slavery was a lot more integral to its economy.
I wanted to bring attention to two posts from Razib Khan's Discover magazine gene expression blog (some of you may have been readers of the still active original gnxp) on the polemic surrounding Pinker's The Better Angels of Our Nature.
Relative Angels and absolute Demons (and the related But peace does reign! )
I generally agree with some of his arguments, but found this quote especially as summing up some of my own sentiments: