Charles Murray has an article in the WSJ called
The New American Divide, which outlines the theme of an emergent cultural shift among white Americans, from his much-discussed new book. After an exposition of the characteristics of the new divide, such as in rates of marriage, illegitimacy, workforce participation, and crime, Murray elaborates on some of the reasons for its emergence.
Why have these new lower and upper classes emerged? For explaining the formation of the new lower class, the easy explanations from the left don't withstand scrutiny. It's not that white working class males can no longer make a "family wage" that enables them to marry. The average male employed in a working-class occupation earned as much in 2010 as he did in 1960. It's not that a bad job market led discouraged men to drop out of the labor force. Labor-force dropout increased just as fast during the boom years of the 1980s, 1990s and 2000s as it did during bad years.
As I've argued in much of my previous work, I think that the reforms of the 1960s jump-started the deterioration. Changes in social policy during the 1960s made it economically more feasible to have a child without having a husband if you were a woman or to get along without a job if you were a man; safer to commit crimes without suffering consequences; and easier to let the government deal with problems in your community that you and your neighbors formerly had to take care of.
But, for practical purposes, understanding why the new lower class got started isn't especially important. Once the deterioration was under way, a self-reinforcing loop took hold as traditionally powerful social norms broke down. Because the process has become self-reinforcing, repealing the reforms of the 1960s (something that's not going to happen) would change the trends slowly at best.
Meanwhile, the formation of the new upper class has been driven by forces that are nobody's fault and resist manipulation. The economic value of brains in the marketplace will continue to increase no matter what, and the most successful of each generation will tend to marry each other no matter what. As a result, the most successful Americans will continue to trend toward consolidation and isolation as a class. Changes in marginal tax rates on the wealthy won't make a difference. Increasing scholarships for working-class children won't make a difference.
It's all a matter of incentives. While lower class people may have - on average! - lower IQs, higher time preference, greater impulsivity, and the like, they, like people everywhere, act in their own self-interest. If it's just as easy to remain outside the workforce as inside it, or as easy to have a child without a pesky husband around, then people will do these things.
One area where I would disagree with Murray is when he writes that the "average male employed in a working-class occupation earned as much in 2010 as he did in 1960." While from a strictly numbers-based standpoint that may be true (I haven't looked up the figures), reality says otherwise. The "reforms" of the 1960s included immigration "reform", and besides that we've had massive illegal immigration as well. Before the 60s, a working-class salary would have sufficed for one to raise a family in a low-crime, white neighborhood with good public schools. Today, not so much. The numbers don't properly reflect the reality.
Another aspect of work now is its uncertainty. Whereas the working stiff pre-60s could reasonably expect to work nearly a lifetime at a decent, possibly union, job, today that worker faces a shifting work environment that could result in a layoff at any time. This will also cause men to be wary of launching into the enterprise of starting a family and working hard toward it.
And then there's no-fault divorce. The upper classes don't worry as much about this because upper-class women are more inclined to have the sort of values that make them stick around and care for their families. Even if awareness of divorce theft is only now dawning on the average man, subconsciously many men must realize that the odds of keeping one's family intact have dropped considerably. That's another impact on incentives.
I'm old enough to remember when cohabitation was very much frowned upon, and I still have the attitude that it's something a decent person - especially a woman - doesn't do. But there don't seem to be too many like me left. Even people older than myself accept it. This touches upon another reason for the social changes Murray describes: the older generation has abdicated some of their moral responsibility, and society as a whole no longer believes in expressing disapproval or shaming the objects of that disapproval.