This chapter is about the logical structure of argument from analogy and its relationship to legal arguments from classification and precedent. Its main purpose is to provide guidance for researchers in artificial intelligence and law on which argumentation scheme for argument from analogy to use, among the leading candidates that are currently available. Arguments from precedent cases to a case at issue are based on underlying arguments from analogy of a kind extremely common both in everyday conversational argumentation and in legal reasoning. There is a very large literature on argument from analogy in argumentation (Guarini, Butchart, Simard Smith et al., 2009), and the topic is fundamentally important for law because of the centrality of arguments from precedent and analogy in Anglo-American law. It is not hard to appreciate this connection, given that according to the rule of stare decisis, the precedent decision of a higher or equal court is binding on a similar current case (Ashley, 1988, 206).

In this chapter, cases are used to argue that arguments from precedent are based on arguments from analogy in legal reasoning and that arguments from analogy are based on a similarity between the two cases held to be analogous. As shown in the chapter, this claim is controversial, because there are different views about how the argumentation scheme for argument from analogy should be formulated (Macagno and Walton, 2009). According to the version of the scheme for argument from analogy argued to be the basic one in this chapter, one of the premises has a requirement holding that there is a similarity between the two cases in point. In this chapter I show how to analyze this notion of similarity using the story-based approach of Bex (2011) and the formal dialogue model for investigating stories of Bex and Prakken (2010). It is shown how an abstract structure called a story scheme can be employed in a way that makes it useful to identify, analyze and evaluate arguments from analogy, and show their function in case-based reasoning where precedents are involved.