Montero De Juan, Francisco Javier2023-06-212023-06-211987De Juan, J.M.: Arrow’s theorem under fuzzy rationality. Syst. Res. 32, 267-273 (1987). https://doi.org/10.1002/bs.38303204030005-794010.1002/bs.3830320403https://hdl.handle.net/20.500.14352/64969This paper deals with living systems at the individual and group levels. In particular, fuzzy set theory is applied to study Arrow's paradox in aggregation preference problems: such impossibility theorems are based on using the Aristotelian logic; thus Lukasievicz's censure to sciences founded on that logic is also fully applicable. In this paper we deal with “rationality” as a fuzzy property, by suggesting a definition of “fuzzy opinion” different from the classical fuzzy preference relation. Whenever this definition is applied, Arrow's theorems are deemed as results about the impossibility of complete rationality. Nevertheless, the possibility of proving the existence of rules with non-complete irrationality is revealedengjournal articlehttps//doi.org/10.1002/bs.3830320403http://onlinelibrary.wiley.com/doi/10.1002/bs.3830320403/abstractrestricted access519.8OrganismGroupAcyclityFuzzy setsGroup decision makingInvestigación operativa (Matemáticas)1207 Investigación Operativa