Exponents of scientism in the past have used it to promote Fabian socialism, Marxism-Leninism, Nazism and more interventionist varieties of liberalism. In doing so, they were invoking the authority of science to legitimise the values of their time and place. Deploying his cod-scientific formula to bolster market liberalism, Pinker does the same.
Other reviews have been to similar effect but no-one does it better than John Gray.
I suspect I may have to read Pinker's book to write an analysis of his twisting of history. As a "liberal" myself, I am in two minds about this "everything is getting better" stuff, but my issue is with Pinker's cartoonish pseudo history in support of this idea.