We analyze two research settings that formalize fundamental divergences among stakeholders about the sustainable management of landscape-one about quantitative water management, the other about agroecological pest control. Our point is that the elicitation and formalization process that took place in both cases fostered collective deliberation, by forcing participants to position their knowledge and values in regards with others. This way, the argumentative quality of the debate grew and we gained new insights on the problems tackled. Our experiences offer a counterpoint to convergence-seeking approaches, supporting that participatory processes should integrate representations in order to build a shared picture. Because this convergence view is at odd with the existence of incommensurabilities that characterize the plurality of people involved in landscape-scale issues, we emphasize the relevance of participatory methods that help focalizing the debate on problematic incommensurabilities, e.g. those that generate discord about the landscape changes to implement, so that they can be overcome. Keywords : agroecological pest management, quantitative water management, social and technical incommensurabilities, participatory modelling and simulation, collective deliberation