One purely consequentialist argument that defenders of tough copyright laws have made is that without strong enforcement of copyright, the incentive to produce new high-quality music will be lower than otherwise. The argument makes sense on its face and the key question then becomes: how strong an argument is it? Specifically, how big is the effect of reduced incentives?

Economist Joel Waldfogel has come up with a clever methodology for looking at that issue. If the incentive for good new music has fallen since Napster and its like, he argues, then older music should become more prominent than otherwise on radio. His findings? Waldfogel writes:

The airplay data allow me to infer vintage quality back to 1960 and exhibit the following pattern (in Figure 2) – quality rises from 1960 to 1970, then falls and remains flat from 1980 to about 1999, with a small bump up in the mid-1990s. After 2000, vintage quality rises sharply, reaching levels not seen since the 1970s.

He has two other measures–record sales and critics’ retrospective lists of the best music–from which he infers the same result: quality has not fallen.

For his graphs, go here.