Understanding Marginal Product via Naked Actors

Daniel Hamermesh writes:

An English newspaper reports that an opera producer has had to cut back the number of naked male actors from 88 to 25 for fear that, given the size of the stage, some of the naked actors would fall into the orchestra pit.  The stage is fixed capital; the marginal product of the 26th naked actor is negative — the production would be severely disrupted if an actor fell off the stage.  Since the opera is about the “sex-crazed Duchess of Argyll,” presumably the marginal product of the first actor is positive — given the Duchess’s proclivities, having zero naked actors would make no sense; marginal products decrease but are still positive up through 25, then become negative thereafter. This is, of course, in the short run; perhaps if there were more time to produce the play, the capital stock could be increased — a larger stage could be built — and the marginal product of the 26th actor would be positive.