Jon Barwise (1942–2000) was a noted scholar of mathematical logic and philosophy who served on the faculties of Yale University, the University of Wisconsin, Stanford University (where he was cofounder and the first director of the Center for the Study of Language and Information), and Indiana University. This collection honors Barwise’s legacy to the academy with current contributions inspired by his diverse fields of interest, from infinitiary logic to natural language, situation semantics, circular claims, and non-well-founded set theory.