@article{fdi:010079916, title = {{M}odelling chance and necessity in natural systems}, author = {{P}lanque, {B}. and {M}ullon, {C}hristian}, editor = {}, language = {{ENG}}, abstract = {{N}early 30 years ago, emerged the concept of deterministic chaos. {W}ith it came sensitivity to initial conditions, nonlinearities, and strange attractors. {T}his constituted a paradigm shift that profoundly altered how numerical modellers approached dynamic systems. {I}t also provided an opportunity to resolve a situation of mutual misunderstanding between scientists and non-scientists about uncertainties and predictability in natural systems. {O}ur proposition is that this issue can be addressed in an original way which involves modelling based on the principles of chance and necessity ({C}a{N}). {W}e outline the conceptual and mathematical principles of {C}a{N} models and present an application of the model to the {B}arents {S}ea food-web. {B}ecause {C}a{N} models rely on concepts easily grasped by all actors, because they are explicit about knowns and unknowns and because the interpretation of their results is simple without being prescriptive, they can be used in a context of participatory management. {W}e propose that, three decades after the emergence of chaos theories, {C}a{N} can be a practical step to reconcile scientists and non-scientists around the modelling of structurally and dynamically complex natural systems, and significantly contribute to ecosystem-based fisheries management.}, keywords = {chaos theory ; constraints ; nonlinear systems ; participatory modelling ; uncertainty ; viability theory}, booktitle = {}, journal = {{I}ces {J}ournal of {M}arine {S}cience}, volume = {77}, numero = {4}, pages = {1573--1588}, ISSN = {1054-3139}, year = {2020}, DOI = {10.1093/icesjms/fsz173}, URL = {https://www.documentation.ird.fr/hor/fdi:010079916}, }