Hardcover book forthcoming. 
Here is a description from the Amazon product page:

Since the 1980s,
society's wealthiest members have claimed an ever-expanding share of income and
property. It has been a true counterrevolution, says Pierre Rosanvallon–the
end of the age of growing equality launched by the American and French
revolutions. And just as significant as the social and economic factors driving
this contemporary inequality has been a loss of faith in the ideal of equality
itself. An ambitious transatlantic history of the struggles that, for two
centuries, put political and economic equality at their heart, The Society of
Equals calls for a new philosophy of social relations to reenergize egalitarian
politics. For eighteenth-century revolutionaries, equality meant understanding
human beings as fundamentally alike and then creating universal political and
economic rights. Rosanvallon sees the roots of today's crisis in the period
1830-1900, when industrialized capitalism threatened to quash these
aspirations. By the early twentieth century, progressive forces had begun to
rectify some imbalances of the Gilded Age, and the modern welfare state
gradually emerged from Depression-era reforms. But new economic shocks in the
1970s began a slide toward inequality that has only gained momentum in the
decades since.