He is using the Enlightenment as the starting point for measuring progress I think, not necessarily embracing all facets of enlightenment thought.
Not really. Pinker claims that the Enlightenment is defined by a “non-negotiable” commitment to reason.
But in A Treatise of Human Nature (1738), Hume wrote: “Reason is, and ought only to be, the slave of the passions and can never pretend to any other office than to serve and obey them.” And Kant’s thesis was “Critique of pure reason”. Schopenhauer proposed that reason was a weak servant of a blind will. Same goes with egalitarianism.
The point is that thinking at that time was much more open and diverse than what Pinker tells us.