It is not rare that in Africa, the leaders propose to thwart the laws of the market for the benefit of their populations. Their plans are often quite simple and convincing. First on board, for some, it is enough to supplement the deficit with tax revenue in order to offer the grower an attractive price, and for others it would be easier to make an agreement with the Western powers. The first has never lasted more than a year -because in general, the leaders quickly realize the barrel of danaides in which they launch themselves-, the second creates a public good which does not fail to attract stowaways .One of the problems with product agreements that has not been highlighted above is the possibility of a divergence between individual interest and collective interest. When the two do not coincide, i.e. in the absence of selective incentives (gratifications or penalties), free-riding strategies appear to be rationally more profitable to individuals.