The economic analysis of product diversity.

Product diversity is a long-debated issue in economics. We remind that mainly two questions have been given answers : (a) To which extent does the market provide diversity ? (b) Why should this diversity be promoted ? The first one stands out as the core of most articles on product diversity, whereas the second one is more evoked than really deepened. However, the economic analysis of product diversity stands out as a paradox. Actually, the definition of diversity itself has been somewhat forgotten. We try to give ways to overcome this absence so that product diversity can eventually be concretely assessed.Product diversity, theory of consumer choice, monopolistic competition.