About the title of today’s blogpost: I couldn’t resist, I’m sorry. The post is about something Noah Smith calls the “The Two Paper Rule”, about which much more below – but the title is courtesy Paul Krugman. About which, also, more below.
Noah wrote this post a while ago, in May 2017. His original post is about a Very Simple Idea that hopefully solves a Very Real Problem. Here’s the Very Real Problem:
I don’t know why academic literatures are so often referred to as “vast” (the phrase goes back well over a century), but it seems like no matter what topic you talk about, someone is always popping up to inform you that there is a “vast literature” on the topic already. This often serves to shut down debate, because it amounts to a demand that before you talk about something, you need to go read voluminous amounts of what others have already written about it. Since vast literatures take many, many hours to read, this represents a significant demand of time and effort. If the vast literature comprises 40 papers, each of which takes an hour to read, that’s one week of full-time work equivalent that people are demanding as a cost of entry just to participate in a debate! So the question is: Is it worth it?
https://noahpinion.substack.com/p/the-two-paper-rule?s=r
Anybody who has suffered through a PhD knows the problem all too well. These days, anybody who has been asked to do a literature review for any paper knows the problem all too well. There is just too much to read.
And folks who want to make sure that uppity folks don’t get, well, too uppity always have a fail-safe defense at the ready: “Have you read all the relevant literature?”. There’s so much stuff that is being published about everything imaginable, that you’re never going to be able to get through even a fraction of it. Why, there’s even a law about it! And there’s a law about the law, which only goes to prove the point further, I suppose.
And here’s Noah’s Very Simple Idea to solve this Very Real Problem:
My solution to this problem is what I call the Two Paper Rule. If you want me to read the vast literature, cite me two papers that are exemplars and paragons of that literature. Foundational papers, key recent innovations – whatever you like (but no review papers or summaries). Just two. I will read them.
https://noahpinion.substack.com/p/the-two-paper-rule?s=r
If these two papers are full of mistakes and bad reasoning, I will feel free to skip the rest of the vast literature. Because if that’s the best you can do, I’ve seen enough.
If these two papers contain little or no original work, and merely link to other papers, I will also feel free to skip the rest of the vast literature. Because you could have just referred me to the papers cited, instead of making me go through an extra layer, I will assume your vast literature is likely to be a mud moat.
And if you can’t cite two papers that serve as paragons or exemplars of the vast literature, it means that the knowledge contained in that vast literature must be very diffuse and sparse. Which means it has a high likelihood of being a mud moat.
I love this idea, and for the following reasons. One, I have an immediate repartee whenever I’m attacked with the “But have you read the literature?” question. And it’s not just a repartee, but a genuine request that serves two purposes. The person asking the question had better be able to come up with at least two papers on the spot. There is otherwise not much point in they having asked the question! Second, assuming the person does come up with two papers I haven’t read, there’s more to read and more to learn.
But second, as a student, what a wonderful way to start building up a repository of papers about a series of subjects! Always ask your profs, no matter the subject, about the two papers worth reading about today’s topic, and keep a running list. (Hint: this is a great way to spend a summer!)
Third, and I’m personally very curious about the results in this case, what about asking young profs and old profs this very question about the same subject? If the answers differ, this is a field worth examining rather more deeply, for it obviously has evolved fairly rapidly. I did my PhD in business cycles, and trust me, the answers would never have been the same – by age, adherence to a particular school of macroeconomics thought, or even by nationality.
Paul Krugman loved the idea (Noah links to Krugman’s blog towards the end of Noah’s blog post, but the link seems to be down. The excerpt below is from Google’s cache):
What about trade? Autor/Dorn/Hanson on the China shock may not be the last word, but surely a revelatory approach. In a strange way, I’d put Subramanian and Kessler in the same category: realizing that this globalization is different from anything that came before is a big deal.
Click here to access the link, too long to post in its entirety
I guess that in a way I’m pushing back against Noah’s nihilism (noahlism?) even while endorsing his method. I think there has been a lot of good economics done, even if there are also vast literatures not worth your time.
… and you now know, of course, where the title of today’s post comes from! What I think Krugman is getting at when he refers to his pushing back against Noah’s idea is that perhaps just two papers is too restrictive. And if that be the case, Tyler Cowen agrees:
The difference between total value and marginal value may be relevant. You might conclude a field literature has low total value, but the marginal value of learning more about that area still could be quite high. That is in part because muddy fields and results don’t spread so readily, and so dipping into the muck can yield some revelations. That is another reason why I would not offer the “two paper standard” as practical advice.
https://marginalrevolution.com/marginalrevolution/2017/05/vast-empirical-literature.html
I have quoted only one of Tyler’s points (he’s got nine others), but in general, I don’t think we should be taking the two part of the two paper rule as being sacrosanct. In some cases you may need to read five, in some rarer cases ten. So long as the number is reasonable (and the standard will change), we can still live with the spirit of the two paper rule.
But if you are a student in college, the two paper rule is a good way to build up a repository of about fifty odd papers that you Really Should Have Read. Twenty five courses (roughly speaking), two papers each.
Well, get started! 🙂