Argumentation and Decision Biases in Multi-Issue Debates∗

I propose a choice-theoretic approach to debates. Two parties dis-agree over multiple issues. Resolution is based on the sets of arguments that are available to each party. Under two axioms, “free disposal” and “procedure invariance”, the resolution is shown to display a “sta-tus quo bias”. The exact form of the bias depends on the kind of argument involved- “pro ” or “con ” arguments. Using an extended model, I show that when parties use both pro and con arguments, only the latter type affects the debate’s resolution. ∗I am grateful to Nuffield College for its hospitality while this project was under-taken. I also thank Elchanan Ben-Porath, Dan Bernhardt, Eddie Dekel, Barton Lipman, Michele Piccione, Ariel Rubinstein, as well as seminar participants at Nuffield College, BU, Columbia, IAS and Yale, for helpful conversations and comments. I am especially indebted to Kfir Eliaz for detailed comments on a previous draft. Financial support from the Arthur Goodhart Fund is gratefully acknowledged