Too bad for reality

This is a follow-up to my yesterday's post about extrapolating long-term growth of Soviet economy in 1961. In his famous 1961 economics textbook, Paul Samuelson projected that the output of Soviet Union will converge to the output of the United States sometime between mid-eighties and mid-nineties. Today this is just a curiosity illustrating how wrong economic projections can be; but even at the time Samuelson first published this projection, he was accused of displaying a pro-Soviet bias.

Just yesterday, economist Bradford DeLong defended Samuelson saying that it's wrong to accuse him of bias because his conclusions were simply a consequence of the Solow growth model, which at the time was the workhorse of growth economics.

The details of the model are not important here; what's important is subjecting predictions of the model to reality checks. Suppose for the sake of the argument that DeLong is right: in 1961 any economist, biased or not, who studied the Solow model and the data that were available then, could not escape the conclusion that in about 25-30 years Soviet economic output will equal the U.S. economic output.

The problem with this line of defense is that a non-biased economist would then conclude that something must be terribly wrong either with the Solow model, or the data that were fed to it, instead of simply taking this ludicrous projection at face value.