Prescriptive rules guide human behavior across various domains of community life, including law, morality, and etiquette. What, specifically, are rules in the eyes of their subjects, i.e., those who are expected to abide by them? Over the last sixty years, theorists in the philosophy of law have offered a useful framework with which to consider this question. Some, following H. L. A. Hart, argue that a rule's text at least sometimes suffices to determine whether the rule itself covers a case. Others, in the spirit of Lon Fuller, believe that there is no way to understand a rule without invoking its purpose--the benevolent ends which it is meant to advance. In this paper we ask whether people associate rules with their textual formulation or their underlying purpose. We find that both text and purpose guide people's reasoning about the scope of a rule. Overall, a rule's text more strongly contributed to rule infraction decisions than did its purpose. The balance of these considerations, however, varied across experimental conditions: In conditions favoring a spontaneous judgment, rule interpretation was affected by moral purposes, whereas analytic conditions resulted in a greater adherence to textual interpretations. In sum, our findings suggest that the philosophical debate between textualism and purposivism partly reflects two broader approaches to normative reasoning that vary within and across individuals. Keywords: experimental jurisprudence, the concept of law, rules, legal psychology, Hart, Fuller.