Formal representations of model-based reasoning and abduction

This special issue of the L. J. of the IGPL ``Formal Representations in Model-Based Reasoning and Abduction'' is based on a selection of the papers that were presented at the International Conference Model-Based Reasoning in Science and Technology. Inferential Models for Logic, Language, Cognition and Computation} (MBR018_SPAIN), held at Tobacco Factory University Building, Seville, Spain, October 24-26, 2018. This event marked the Twentieth anniversary of the Model-Based Reasoning Conferences, since the first meeting was held at the Collegio Ghislieri, University of Pavia, Pavia, Italy, in December 1998.