This week’s Economist asks why there is an invisible hand on the keyboard:

Not all economics bloggers toil entirely for nothing. Mr Mankiw frequently plugs his textbook. Brad Setser, of Roubini Global Economics, an economic-analysis website, is paid to spend two to three hours or so each day blogging as a part of his job. His blog, rgemonitor.com/blog/setser, often concentrates on macroeconomic topics, notably China. Each week, 3,000 people read it—more than bought his last book. “I certainly have not found a comparable way to get my ideas out. It allows me to have a voice I would not otherwise get,” Mr Setser says. Blogs have enabled economists to turn their microphones into megaphones. In this model, the value of influence is priceless.

Not up to the usual high standard of The Economist.

Economists blog because most of us believe that information and knowledge are more valuable shared than kept secret. As knowledge workers, we are valued by the information we share, not the secrets we keep.  Blogging is a hugely efficient way of sharing some kinds of information.