The Glass Half Full

Tyler Cowen praises a book by Alan MacFarlane and Gerry Martin, which documents the importance of glass in the development of human science and technology. I have little doubt that glass is as supremely important as the authors suggest. But, not having read the book, I wonder whether the authors pay sufficient attention to the question of alternative history: what other discoveries might have been made in the absence of glass?

It’s common for people to make grand statements about the role of railroads in the growth of the American economy – that they drastically lowered the cost of transporting agricultural and industrial goods, that they made possible the settling of the American West, that they transformed managerial techniques, and so on. Much of this is true. But as economic historian Robert Fogel observed, the American economy without railroads would not have sat still, or just continued in its old tracks. Fogel figured that, without railroads, people would have built many more canals (and made more use of wagons as well). He used topographical maps to surmised where canals would have been built in an America without railroads. He eventually concluded that the American economy would have done almost as well with railroads as without them.

Other economists have disputed Fogel’s analysis, and there is much to dispute. But his basic analytical framework is clearly correct: you have to ask how people would have applied their motivation and ingenuity in a world without the technology in question. Maybe the would have come up with new technologies, or extended the use of old ones. Again, I haven’t read MacFarlane and Martin’s book. Tyler says the authors are “properly subtle and qualify their thesis in the required ways.” Maybe this is what he means.