Complex Cases and Legitimation Inferences: Extending the Toulmin Model to Deliberative Argument in Controversy

A warrant may be grounded in personal testimony, technical method, or public consensus. The justified choice of a field, in authorizing the warrant and providing further extension of support constitutes a legitimation inference. Complex cases evolve when there are a surplus of good reasons as potential support for a claim, and a choice must be made either to select a single ground for the claim or to advance independently valid reasons, differentially grounded, as support. Complex cases enter the realm of controversy when not all relevant grounds offer the same degree of support or point in the same direction, and a choice to select some grounds and discard others must be justified. The justification of the selection of grounds constitutes a legitimation warrant—a missing element of the Toulmin model