A note on the Exclusion Principle

The Exclusion Principle (Baye et alii, 1993) asserts that, in an all-pay auction with fully informed participants, it might be profitable for the seller to exclude those bidders whose valuations are the largest. Menicucci (2006) shows that banning (ex-ante symmetric) bidders can raise expected revenue also in a setting in which the seller regards valuations as identically and independently distributed. We prove that the latter occurrence cannot arise if valuations are distributed according to a monotonic hazard rate.