Context sensitive case comparisons in practical ethics: reasoning about reasons

Comparative evaluation appears to be an important strategy for addressing problems in weak analytic domains, such as the law and practical ethics. Comparisons to paradigm, hypothetical, orpast cases may help a reasoner make decisions about a current dilemma. We are investigating the uses of comparative evaluation in practical ethical reasoning, and whether recent philosophical models of casuistic reasoning in ethics rnuy contribute to developing models of comparative evaluation. Weare also interested in exploring how our work contributes to AI and Law. A good comparative reasonec 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 presenting ethical dilemmas about whether to tell the truth by marshaling relevant similarities and differences in a context sensitive rnanne~ The program has a variety of methods for reasoning about reasons. These include classifying reasons as principled or altruistic, comparing the strengths of reasons, and qualifying reasons by participants’ roles and the criticality of consequences. We describe a knowledge representation and marshaling process for this domain. In an evaluation of the program, five professional ethicists scored the program k output for randomlyselected comparisons. The work contributes to context sensitive similarity assessment and to models of argumentation in weak analytic domains.