The Theory of Interstellar Trade

I did not think that Paul Krugman was still writing academic papers. Nor have I seen any evidence in the last decade that he still has any sense of humor.

Consequently, I was surprised to see an article written by him entitled “The Theory of Interstellar Trade,” published recently in the journal Economic Inquiry. Here is the abstract of the paper:

This article extends interplanetary trade theory to an interstellar setting. It is chiefly concerned with the following question: how should interest charges on goods in transit be computed when the goods travel at close to the speed of light? This is a problem because the time taken in transit will appear less to an observer traveling with the goods than to a stationary observer. A solution is derived from economic theory, and two useless but true theorems are proved.

A quick look at the acknowledgments, however, clears things up. The original manuscript was written in July 1978, when Krugman was an active researcher and being a curmudgeon wasn’t part of his professional identity.

Peter R

Krugman was a bit harsh on his review of superfreakonomics. I like Krugman, but I feel like Levitt is right to be upset.


This is paper is really hilarious, but your comments about Paul Krugman's sense of humor are not. His blog is full of funny remarks, pop culture references and even nonsensical humor. You should read it for yourself :)

David Chowes, New York City

[Re; Comments # 7, 8, & 19]

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Did u jut diss Krugman in public? You just went so down in my cool-o-meter... but I'm not sure cuz your book are so fun... now you're making me suffer from cognitive dissonance...


Oh well, I've been in your shoes. I produced a writing which had significant scientific errors - and I was lambasted, publically, by a Ph.D. After being livid for about 2 years, I decided to learn from his words and it turned out to be a huge blessing. I am a much better scientist for it.

Krugman was dead on - you guys were and continue to be completely inaccurate on environmental issues. But you've stepped into the door of the science of the planet. Don't stop now, learn from your mistakes and rise to a new level.

Then you can have the last laugh when you buy Krugman a birthday gift from Gliese 581.

Gentle Reader, Swarthmore, PA

When I listened to the "If Economists Ruled the World" episode of the Freakonomics podcast, I thought it was a brilliant satire. After all, the whole Economists-as-Spock meme is very 2004.

This post must, therefore, be the punchline - since there's nothing so un-dispassionate, un-cool, un-intellectual as a penny-ante blog flight.

Bravo! I applaud your performance art.


Prof. Krugman's very well-read in Science Fiction, and took part in a panel discussion at WorldCon with Charlie Stross - one of the few authors who puts some thought into the economics of the worlds he creates, as well as the rocketships and zapguns.

I'd recommend a close reading of Halting State (author: C. Stross), which is driven by the question 'What is money?' in a world uncomfortably close to our own.


Oh for crying out loud, lighten up people. Dr. Levitt called Krugman a humorless curmudgeon while simultaneously citing a source that suggests the exact opposite. This is playful ribbing at worst.


+1 that this feels like odd sniping. He is a curmudgeon, but he does frequently display a sense of humor on his blog.

nick spinelli

It's painfully obvious, Mr. Levitt, that while Krugman censors virtually any criticism on his blog, that you believe in free expression. The irony is, we have to read the same lemming responses, from the same people, both on your blog, and his.

You are engaging, funny, and intellectually honest. Krugman is 0 for 3 in those categories, but he could still play for the Mets w/ that BA.

Finally, Krugman is insanely jealous of your success. That is a source of joy for all of us free thinkers.


At least Paul Krugman has a Nobel Prize...

John Samuel

Oh dear. And he says such nice things about you. Krugman wins on points.

Don A

The Theory of Interstellar Trade is every bit as useful and gripping as learning why drug dealers live at home. Quite possibly much more useful.

Griff Wodtke

It seems foolish for you to publish something like this that so clearly shows your failure to do your homework, e.g., scan a few of PK's blog entries. I just confirms what many have suspected.


How much would the klingons pay for the last dying breath of Milton Friedman?


Note that everyone objecting to Levitt's assertion that Krugman is humorless; nobody objects to Levitt's point that Krugman - the academic economist who writes opinion columns for the Times - no longer produces academic work. I think one of Levitt's two digs at Krugman is far more relevant to Krugman's place in the world and it's not the one being talked about in the comments...


Wow, another ad hominem attack on Krugman. How unoriginal. I don't always agree with Krugman, but at least his theories are based on models and evidence.


I love your books and posts but you should read more Nobel prize papers in your field. You can make a quick search of recent papers of Krugman in Google Scholar. There are plenty of them!!

Goran Semb

I'm afraid comments like that don't make you come out as a better person than Prof. Krugman -- quite the opposite, actually



Thank you your input about the newspaper business. However, in the blog business, as Mr. Krugman has expressly stated, he writes his own headlines. Nice try.