American politicians have long been troubled by the question of whether or not to deploy a national missile defense system. The argument has focused upon the questions of cost, both political and fiscal, plus the reliability of the technologies. This study places that debate within the context of an ongoing controversy over the direction of American foreign and defense policy since the 1950s. Since that time several distinct worldviews (labeled Believers, Pragmatists, and Wilsonians) have been articulated. Those worldviews structure how technology tests and costs are evaluated regardless of outcomes. Politics, not technological proficiency, drives policy decisions.