Paul Krugman is critical of Jeb Bush who hopes to be the third president from the Bush family. In particular, he criticized him for refusing to admit that his brother made a serious mistake about the invasion of Iraq. Moreover, he reported that Jeb's foreign policy advisers include several of his brother's advisers who do not admit that they were wrong about Iraq. Jeb Bush's economic advisers are similar to his foreign policy advisers. They adhere to same set of economic ideologies that never change in face of contradictory evidence. In fact, all of the GOP candidates for the presidential nomination share the same set of economic ideologies. Krugman refers to the foreign policy and economic advisers as a "fraternity of failure". They share a similar ideology that is impervious to failure. If they admit to mistakes they are raising questions about the ideology and they will be expelled from the fraternity.
It is in the nature of political parties to have a common set of values. If one looks at the Democratic Party its values differ from those of the Republican Party. There would be no point in having political parties if this were not the case. On the other hand, the Democratic Party has moved much closer to the center over the last 40 years. The Republican Party has moved further to the right over the same period. In general, the political and economic ideas of liberals are more subject to disconfirming evidence. In fact, it is very hard to build a consensus on most issues within the Democratic Party.