Experimental Investigation of Conditional and Non-Conditional Presuppositions

Conditional sentences with a presupposition trigger in the consequent, if φ, then ψp, show peculiar projection properties. That is, the entire sentence seem to presuppose that p in some cases (nonconditional presupposition), and that φ→ p (conditional presupposition) in some other cases. We present three picture matching experiments to address two theoretical issues raised by this phenomenon. Experiments 1 and 2 address the Selection Problem, i.e. Which presupposition obtains when? The results indicate that the dependency of the presupposition p on the antecedent φ affects the choice of the inference. Experiment 3 attempts to answer the Generation Problem, i.e. How are the two presuppositions derived?