It's certainly true that the ideal of the scientific method is vastly better than the practice of economists, but I think that majoring in economics provides better training for a rationalist than majoring in any of the sciences does.
I disagree. Insofar as their body of expertise is sound, economists are able to mount sound criticism against ideas that contradict the well-established knowledge in their profession, but this is not different from any other area. I don't observe that they are exceptionally rational when it comes to questions that can't be readily answered using their standard knowledge and methods.
What's more, when it comes to questioning the soundness and justification of ideas that are widely accepted within their profession, economists are definitely far worse than natural scientists -- especially when it comes to ideas that they use to support their own ideological positions. When you ask physicists how they justify their physics, you get direct, detailed, and sound answers that go to the heart of the matter. In contrast, on many topics, economists are apt to react with a smug, dismissive, and stonewalling attitude instead. (With depressingly few honorable exceptions.)
Now, it does happen that there are a great many unsound ideas that sound nice and attractive to economically illiterate general public and intellectuals (often including smart natural scientists), and an economist is likely to be capable of discussing these much more rationally. On the other hand, there are many matters of widespread agreement or even near-consensus in modern economics that would not stand up to rational scrutiny, which are sometimes little more than a sophisticated fig-leaf for ideology. In these matters, various fringe low-status contrarians and even naive folk economics can be much closer to reality, however much credentialed economists tend to scoff at them. Clearly, a training in economics may well cause one to become less rational on such topics.
On the other hand, there are many matters of widespread agreement or even near-consensus in modern economics that would not stand up to rational scrutiny, which are sometimes little more than a sophisticated fig-leaf for ideology.
Examples would help (if they don't contain much mind-killing potency).
A Wall Street Journal article by Harvard professor of government Harvey Mansfield claims that the social sciences and humanities are inferior to the sciences. The article implicitly urges undergraduates to major in science. From the article:
Do you agree with this? As a game theorist I probably have a rather biased view of the situation. It's certainly true that the ideal of the scientific method is vastly better than the practice of economists, but I think that majoring in economics provides better training for a rationalist than majoring in any of the sciences does.
Economics explicitly considers what it means to be rational. Although it infrequently considers ways in which humans are irrational, I'm under the impression that the hard sciences never do this. Furthermore, because economists can almost never perform replicable experiments we have to rely on what everyone in the profession recognizes as messy data; therefore we’re far more equipped than hard scientists to understand the limits of using statistical inference to draw conclusions from real world situations. Although I have seen no data on this, I bet that a claim by nutritionists that they have found a strong causal link between some X and heart disease would be treated with far more skepticism by the average economist than the average hard scientist.