Learning to Agree under Pseudo-Reciprocity

We characterize the communication networks that ensure consensus in rational social learning under the sure-thing principle. A network ensures consensus if and only if it is pseudo-reciprocal, a property under which reciprocity may fail between individuals but holds at a coarser group level. Prior work has assumed message exchange to be bidirectional, yet such pairwise reciprocity proves largely dispensable. We show that a single bidirectional link can suffice, however large the population.