Scott Sumner identifies some weaknesses in left wing thinkers:
Weakness #1: Intellectuals on the left go through the following thought process. First they observe a “problem.” Then they declare a “market failure.” Then they consider what sort of government policy could remedy the problem. What they often overlook is that the problem is usually the side effect of other government policies. That doesn’t mean the free market solution is always best; there may be cases where those other government policies are needed, and hence further regulation is required to overcome the side effects. The real problem is that it’s much easier to dream up straightforward government policies to remedy a situation, than to envision how a problem is the side effect of other regulations. Or what further side effects will result from your proposed solution. That biases pundits toward supporting far too much government involvement in the economy
Weakness #2: Left wing intellectuals believe they are pro-science and the right is anti-science. They are right that part of the right is anti-science, but they are equally anti-science. A few years back a distinguished left wing nerd was fired from his job as president of Harvard for making a very familiar scientific argument; that the distribution of innate intellectual skills among males might have fatter tails than distribution of innate intellectual skills among females. (BTW, lots of people thought Summers claimed men were smarter than women—not so. He said the distribution of skills might be wider. Most of his opponents didn’t know enough about “science” to understand that distinction.) Whether you agree with Summers’ theory, or whether you agree with me on global warming is immaterial. There’s lots of data supporting both theories, and some against. What matters is that the left is just as intolerant as the right when their ox is being gored.