Our aim in this section was not to deal with the details of the heated controversy concerning sensitivity to scope (see, for example, Carson and Mitchell, 1995; Frederick and Fischhoff, 1998). Our goal is both simpler and more ambitious: we hope to have shown that inadequate sensitivity to scope in CV surveys that employ the quantity design is ine¨itable , because this phenomenon is an instance of a broad class of similar effects that have been observed in diverse contexts and are explained by a single psychological principle.