Both intuitively, and according to similaritybased theories of induction, relevant evidence raises argument strength when it is positive and lowers it when it is negative. In three experiments, we tested the hypothesis that argument strength can actually increase when negative evidence is introduced. Two kinds of argument were compared through forced choice or sequential evaluation: single positive arguments (e.g., “Shostakovich’s music causes alpha waves in the brain; therefore, Bach’s music causes alpha waves in the brain”) and double mixed arguments (e.g., “Shostakovich’s music causes alpha waves in the brain, X’s music DOES NOT; therefore, Bach’s music causes alpha waves in the brain”). Negative evidence in the second premise lowered credence when it applied to an item X from the same subcategory (e.g., Haydn) and raised it when it applied to a different subcategory (e.g., AC/DC). The results constitute a new constraint on models of induction.

Induction . Negative evidence . Categories. Models of induction
hdl.handle.net/1765/125403
Memory and Cognition
Department of Psychology

Heussen, D., Voorspoels, W, Verheyen, S, Storms, G, & Hampton, J. A. (2011). Raising argument strength using negative evidence: A constraint on models of induction. Memory and Cognition, 39, 1496–1507. Retrieved from http://hdl.handle.net/1765/125403