In order to justify agricultural income support, current rhetoric insists on equity considerations. Yet, one does not see any reason to be more equitable with respect to farmers than to any other category. By contrast, protecting consumers against large, market generated price fluctuations stands as a solid ground to found farm subsidies legitimacy. In order to bring support to this idea, it is shown that the combined action of uncertainty, factor fixity, absence of economies of scale, and demand rigidity logically leads free agricultural markets toward chaotic regimes (in the technical, mathematical meaning of the word), with non periodical, self generated fluctuations. No exogenous perturbations, such as climatic accidents or exchange market hazards are necessary for such scenarii to occur.
