Proceedings of the Annual Meeting of the Cognitive Science Society

Case-based comparative evaluation appears to be an important strat?egy for addressing problems in weak analytic domains, such as the law and practical ethics. Comparisons to paradigm, hypothetical, or past cases may help a reasoner make decisions about a current dilemma. W e are investigating the uses of comparative evaluation in practical ethical reasoning, and whether recent philosophical models of casuistic rea?somng in medical ethics may contribute to developing models of com?parative evaluation. A good comparative reasoner, we believe, should be able to integrate abstract knowledge of reasons and principles into its analysis and still take a problem's context and details adequately into account. TRUTH-TELLER is a program we have developed that compares pairs of cases presentmg ethical dilemmas about whether to tell the truth by marshaling relevant similarities and differences in a context sensitive manner. The program has a variety of methods for reasoning about reasons. These include classifying reasons as prin?cipled or altruistic, comparing the strengths of reasons, and qualifying reasons by participants' roles and the criticality of consequences. W e describe a knowledge representation and comparative evaluation pro?cess for this domain. In an evaluation of the program, five professional ethicists scored the program's output for randomly-selected pairs of cases. The work contributes to context sensitive similarity assessment and to models of argumentation in weak analytic domains.