Optimists and liberals

In yesterday's NY Times, David Brooks wrote on The Virtues Of Virtue, "According to the Bureau of Justice Statistics, the rate of family violence in this country has dropped by more than half since 1993. ..." In the same section, there is "Where Killers Are Out of Style ... The murder rate in New York is still falling. How low can it go?"

Brooks tries to explain the good news and notes: "The first thing that has happened is that people have stopped believing in stupid ideas: that the traditional family is obsolete, that drugs are liberating that every adolescent's social duty is to rebel."

I agree. These and other 1960s ideas (many still popular on the left to this day) are both stupid and ruinous.

Why do conservatives point to the positives where they exist while liberals do not? There are many reasons, but among them is the inability to stop believing in exactly the dumb ideas that Brooks cites.