  The Boolean lattice of logical statements induces the free distributive
lattice of questions. Inclusion on this lattice is based on whether one
question answers another. Generalizing the zeta function of the question
lattice leads to a valuation called relevance or bearing, which is a measure of
the degree to which one question answers another. Richard Cox conjectured that
this degree can be expressed as a generalized entropy. With the assistance of
yet another important result from Janos Aczel, I show that this is indeed the
case, and that the resulting inquiry calculus is a natural generalization of
information theory. This approach provides a new perspective on the Principle
of Maximum Entropy.
