The Enlightenment: progressive or reactionary?

Not only do scholars dispute details of the Enlightenment; nowadays there are those who claim that the Enlightenment didn’t really happen at all. For example:

As the intellectual historian John Robertson pointed out in The Enlightenment: a very short introduction (2015), two distinct conceptions of the European Enlightenment are currently in circulation. According to the first, commonly held by philosophers and public intellectuals, the Enlightenment was a coherent project of religious secularisation, philosophical and scientific modernisation, and political liberalisation … The second conception is typically held by historians, who have largely abandoned grand narratives of the Enlightenment … many of those we refer to as Enlightenment thinkers were not politically or religiously “progressive” in any way.

Dmitri Levitin, review of The Republic of Arabic Letters (LRB, 22 November 2018)

I assume Rousseau is intended as a member of that second group – Enlightenment thinkers displaying some remarkably anti-Enlightenment characteristics.  Rousseau is so different to Voltaire and Diderot that is is difficult to think of a definition of Enlightenment that encompasses all three. 

One area that reveals Enlightenment thinkers being anything but progressive is easily found by examining their statements on Islam. Levitin, in the same review, reveals some surprising bias about Islam by thinkers who should have known better, including Voltaire.

Voltaire perpetuated the myth of Ottoman backwardness; Gibbon … said it [Islamic civilization) lacked “the spirit of enquiry and toleration”. (LRB 22 November 2018)