That the participants in the Enlightenment generally believed "that the goal of life was happiness," and that $"[$h$]$appiness and its equivalents $...$ epitomize $...$ 'the commitment to understanding, and hence to advancing, the causes and conditions of human betterment in this world'," is the central thesis advanced by which of the following:

Dumarsais' definition of the Philosopher "Philosophe."

The introduction to the assigned secondary source reading book by Ritchie Robertson.

Jean le Rond d'Alembert's "Preliminary Discourse to the Encyclop$$die$."$