| A cognitive analysis of the information and problem-solving components needed for legal reasoning is presented, focusing on the judicial interpretation of vague legal rules. There are four perspectives or roles from which lawyers reason: the philosophic, judicial, advisory, and advocatory. The major structural components of the law are the conditions and consequences of rules, and the purposes of rules. Purposes are divided into policies and principles. To evaluate a rule justified on policy grounds, we need to analyse the cause-and-effect relation between rule and purpose. Evaluating rules justified by principle does not require causal reasoning.;There are two sources of legal rules, legislative enactments and judicial opinions. The source can affect the type of reasoning used for interpretation. Several cognitive strategies for interpreting vague language and deciding if a rule applies to a case are modeled. These are the literal, the instrumental, and strategies that weight and combine literal and instrumental factors. Literal strategies highlight the lexical properties of rule conditions, and require that reasoners make category membership or similarity judgments. Instrumental strategies highlight the purpose of a rule and the causal link between the rule and purpose. The strategies correspond to alternative theories of jurisprudence.;A computerized test designed to diagnose which strategy a person uses was created and administered to law students. Results demonstrate that for most people, ratings of the applicability of a rule to a case can be well predicted by two factors: (1) the extent to which the facts of a case are subsumed under the categorical terms in rule conditions, and (2) how useful applying the rule's consequence to the facts of a case would be for accomplishing the rule's purpose. Statutes and precedents are treated differently by some reasoners. The implications of this model, and the computerized assessment, for legal education, legal practice, and the development of computer-assisted legal reasoning systems are discussed. Our understanding of high-level reasoning skills is greatly increased by a cognitive analysis. A model of legal reasoning demonstrates how legal and scientific thinking can be integrated. |
