Résumé : Putting agricultural systems on a more sustainable path is a crucial policy issue. Within that context, the objective of this paper is to show how the unsustainable character of current agricultural systems is strongly related to the prevailing rationale of mainstream economics and the Cartesian-Newtonian worldview on which it is founded. Using the example of the transformation of post-war agriculture in France, our analysis underlines the profound influence of the logic of mainstream economics on the modernisation of agricultural systems. The resulting transformation of agricultural systems based on the triptych specialisation-intensification-concentration is then further explored regarding its negative impacts in terms of sustainability. Particular attention is dedicated to environmental impacts, given their magnitude and the fact that mainstream economics, because of its “mechanistic reductionist” framework, has intrinsic difficulties in dealing with them. Since the fundamental assumptions of mainstream economics are being strongly challenged, it becomes legitimate to resort to an alternative economic framework for designing appropriate policies and measures. Given that many empirical studies demonstrates that agricultural systems may be locked-in to some extent, the choice an evolutionary line of thought in an ecological perspective is quite straightforward. This approach of economic change both underlines its historically-contingent nature and the role played by systemic interdependencies. Through underlining the path-dependence of agricultural systems, the use of the evolutionary framework in an ecological perspective allows us to shed a new light on their transformation by suggesting some strategies (i.e. niche accumulation and hybridisation) that have proven efficient in overcoming cases of lock-in in other fields.