The debate has been taken up by Nicolas Carr at Rough Type. In one sense I am surprised it has taken so long for economists to bring this up.
Mankiw's move prompted Dani Rodrik, another Harvard blogger, to wonder, "Is the econ-blogosphere unsustainable?" As the smartest economist-bloggers become more popular, he theorized, they will spend increasing amounts of time working on their blogs, steadily raising their opportunity costs without producing much if any income, until at some point blogging becomes, well, uneconomical: "So if economists with high opportunity costs of time start to get out, shall we have a lemons problem on our hands? Will eventually the only prolific bloggers remain the ones that are not worth reading?" Does, in other words, the economics of blogging guarantee that only the mediocre and the worthless will survive - the ones whose time isn't particularly valuable to begin with?
Free Exchange stressed that he wasn't saying that academic economists should "leave off blogging," but nevertheless his point implies that it's probably not a good idea for the best economists to spend time blogging that might have instead gone into research and journal-writing. They should, to ensure the most efficient possible idea market, focus on the areas in which they hold the greatest advantage, and let the amateurs crank out the blog posts.
But what's left out of all these economic equations is the ego-gratification that comes from being a popular blogger. Because blogging is such a personal pursuit, with strong and immediate ego-rewards, it can be irrationally seductive, particularly to highly competitive overachievers. The hazard - and this applies as well to disciplines beyond economics - is that extraordinarily talented individuals may end up, like lab mice drinking sugar water, spending more time blogging than they should, even though their comparative advantage is smaller in blogging than it is elsewhere. Distorted by noneconomic but nonetheless powerful rewards, the idea market would become less efficient than it should be, and we'd all suffer as a result. The real danger, in other words, may not be that the "lemons" - the "tolerable bloggers" - will take over as the mainstays of the blogosphere but that they won't.
The quotes from the Carr article all make good points. However, a blogger does not have to post every day and nor does the post have to be ground breaking and filled with originality and wit (as we show clearly at "Globalisation and the Environment").
I post merely on what I find interesting/amusing/strange and hope there is some sort of positive externality for readers as there is for myself by informing and setting my own research agenda. Whilst it might be true that there is an opportunity cost in terms of writing research papers, the ability of blogging to identify the questions worth writing a paper on more than outweigh the costs.