How Different Is Different? Arguing About the Significance of Similarities and Differences

Our instructional program, CATO, uses a model of case-based legal argument to teach law students basic skills of making arguments with cases. CATO represents abstract knowledge about the meaning of the similarities and differences between cases in a Factor Hierarchy, in which the ‘factors’ used to represent case facts are linked to higher level concerns and legal issues. The Factor Hierarchy enables CATO to identify issues in a problem and to organize multicase arguments by issues. The Factor Hierarchy also helps to assess and explain the importance of differences in terms of more abstract knowledge, yet in a manner sensitive to the context of the particular problem and case being compared and the argument for which the comparison is made.