"The best of all possible worlds" is a simplistic expression stemming from the philosopher Gottfried Wilhelm Leibniz's complex 1710 "Essays of Theodicy." Voltaire lampooned it in his "Candide," when he had his character Pangloss declare that "all is for the best in the best of all possible worlds."

This is the background of the concerted effort that is now underway to promote a new optimism, armed with data and also backed by philosophy.

It was around the year 2000, at the height of the post-Cold War era and the rise of globalization, when the optimists first staged a comeback. However, the momentum they had hoped for did not materialize.