According to Brooks, most people attribute this shift to the baby boomer generation durning the period of the 1960's. However, Brooks asserts it was actually the greatest generation who made the shift as a reaction to 16 years of suffering from the Great Depression and World War II. Brooks also correctly asserts that the shift has some merit, even as he asserts the importance of restoring some balance to our social vision of human nature and a life well-lived.
I like this book a lot. It is my favorite read of 2020. The contrast between the traditional moral ecology rooted in a vision of human frailty and one rooted in human potential seems to mirror the dichotomy between constrained and unconstrained visions in Thomas Sowell's classic work A Conflict of Visions (see my review of Conflict).