Abstract
The debate between realism and instrumentalism is at an impasse. That is the state of the art, and the competing positions and arguments are best understood by seeing how they have produced it. When scientists familiar with a common body of evidence, and with the resources of alternative theories for handling that evidence, nevertheless disagree as to which theory is best, something has gone wrong methodologically. Standards of evidential warrant, the criteria by which theories are to be judged, and not just the theories themselves, are in dispute. When philosophers disagree about theories of science, without disputing the evidence brought to bear for or against the contenders, the legitimacy of standards of philosophical argument is similarly unresolved. In the debate over realism the central bone of contention is abductive inference.