I've been listening to Russ Roberts' podcasts EconTalk for many years and it is one of my favorites, even though I often disagree. In Krugman is human, just like me he writes:
Krugman has responded to my claims about empirical evidence, confirmation bias, and the lack of science in macro policy discussions. Here's the argument so far.
I suggested on Twitter that economists see what they want to see. We tend to latch on to evidence that supports our worldview and ideology and ignore evidence to the contrary.
Krugman responded by saying that might be true of me, but not him. He is a Keynesian because of the evidence. He is mainly unbiased. Nor does his desire for a larger government role in the economy pre-dispose him to interpret the effects of fiscal policy in a particular way.
I responded that the evidence in support of Keynesian fiscal policy is very mixed. There is too much evidence. People on each side of this debate can easily find lots of evidence--some historical, some econometric to support there view. As an example of the challenge of using evidence vs. bias to reach a policy conclusion, I pointed out that in 2013, Krugman predicted that the fiscal contraction from increased taxes and reduced spending would hurt the economy. When economic growth turned out to be healthy in 2013 and greater than in 2012, Krugman responded by arguing that "other stuff" explained the failure of his prediction. This is a common response by people on both side of these kinds of debates. Very rarely does one side concede that their worldview may need revision. There is always "other stuff."
What and why people believe fascinates me and I've blogged about it and the associated confirmation bias a fair amount. It's been interesting for me to see how Roberts has, over the years I've been listening to him, come to realize that everyone, including himself, is susceptible to easily accepting evidence that supports their view while ignoring evidence that doesn't. However knowing this doesn't stop him from taking sides as witnessed that he blogs at Cafe Hayek.
But still that is better than claiming to be (mostly) bias free. Saying your predictions failed because "other stuff" happened is similar to some religious cult leader predicting the end of the universe and then when it doesn't occur saying it was because people didn't pray enough. Why when a prediction does come true, do you never hear anyone say it's because ""other stuff" happened?
For more discussion on the topic see Noah Smith's blog Economic arguments as stalking horses.
Following in the footsteps of the Open Science Framework, when economists make predictions they need to write down in advance what they think will happen and when and under what conditions, and what outcome would prove them wrong.