Ryan's post makes a very good point regarding the interventionist mindset and the application of fallacious reasoning. I have noticed that when Krugman is challenged either on his predictions or the results of policy, he often employs the informal fallacy known as Appeal to Authority.
For example, he frequently cites the Congressional Budget Office predictions (he tends to ignore failed predictions from the CBO or claims they are wrong only when a Republican is in the White House) when he is arguing tax policy or is claiming that ObamaCare will lower medical costs. One thing I have found is that he seems to be incapable of dealing with simple economic logic, and he often will do things like mistake marginal revenue product for total revenue product when he is arguing that an increase in the minimum wage will increase overall spending, which will revive the economy. In other words, he is not a particularly good economist, but since he has a Nobel Prize, he is cited as an "expert."