The papers in this Forum discussion debate various aspects of my maximum entropy model of community assembly. The questions raised centre around (1) the possible mechanisms generating the patterns predicted by my maxent model of community assembly, and (2) the appropriate statistical methods for testing the patterns. Here I briefly explain the proposed mechanistic basis of the model: natural selection occurring between individuals of different species. If trait differences are linked to differential demographic probabilities (i.e. fitness differences) then natural selection will constrain the average trait values found in the community and such average (‘community-aggregated’) traits will then possess information that is translated into the maximum entropy probabilities. If community assembly is strictly neutral then the maxent model will have no predictive ability. This also justifies the null model, and the permutation test, proposed by Roxburgh and Mokany.