What is the optimum length of copyright (from a social benefit perspective)? Rufus Pollock calculates it to be 14 years in this paper (pdf). He’s a Ph.D. candidate at Cambridge University, and reached his conclusion based on a few assumptions (which he backs up with data): (a) that as copyright length increases, it encourages the creation of new works, (b) up to a certain point, after which it can inhibit the creation of new works, and (c) that the optimal length of copyright is in part a function of the cost of production, so that as the cost of production falls so to does the optimal copyright length. [slashdot]