In this innovative work, Robert Delorme comprehensively explores uncertainty (the irreducibility to numerically measurable probabilities) and ignorance in economics, management and the social sciences through an alternative, systematically built analytical framework.This unique book takes uncertainty and ignorance seriously and addresses them as instances of ‘deep complexity’ (problem situations so deeply ill-structured that they cannot be grasped with the concepts and tools of classical science). Building on the works of Herbert Simon, Heinz von Foerster and John von Neumann, the author develops an alternative framework that encompasses, rather than rejects, the classical framework. The outcome of this novel approach is ‘effective deep complexity’, comprising three aspects: an effective alternative framework, which brings an answer to a fundamental issue on the implications of uncertainty for scientific reasoning; a behavioural theory of deeply ill-structured problem-situations; and a decision-and-action support system.Robert Delorme has provided an invaluable resource for researchers and academics in the broad realm of economics and business management. This work will also appeal to decision-makers and policymakers due to its practical applications, including structural economic policy, transport and industry.