Comment on the Cardozo conference on graphic and visual representations of evidence and inference in legal settings

The paper I presented at the conference gave graphical form to certain kinds of legal arguments: arguments from precedent cases (Loui, 2007). I did not intend to impose a kind of discipline on those who make such arguments. My research aims at elucidating the various forms of reasoning, proposing rules that capture their patterns and regularities, even if those rules and patterns might seem naive to experts at arguing from precedent. To a formalist, a few good rules are better than no rules, especially since artificial intelligence (AI) depends on having rules for computers to follow. A graphical way of diagramming such arguments is simply an alternative way to present the disciplined arguments and to make them comprehensible to humans, especially when the symbols are being manipulated by automata. For some of my logic colleagues, however, the implicit value of such a graphical mechanism is normative: one presumes to improve the quality of legal arguments by imposing a canonical form. This is the presumption that ran badly afoul at this conference. Why should someone who is already very good at making arguments be interested in following our rules for diagramming their arguments? My idea was simply to improve on the ubiquitous ‘Toulmin form’ for diagramming defeasible arguments (Hitchcock and Verheij, 2006). Analogies are a specific kind of argument requiring a specific kind of Toulmin structure. My theory is itself a putative improvement on existing theories of analogy from precedent. Hence, by claiming to have an improved theory of analogical argument, and claiming to refine Toulmin diagrams with that theory, it is easy to imagine that people could be led to better arguments, better rationality and better decision making, by using new diagramming conventions. This is what many formalists and many research computer scientists engaged in logic and visualization would have claimed. But why should it be true? Why are more diagramming rules better than fewer? I did not explicitly claim that people who use our diagrams make better arguments. I would not even have claimed that people who use Toulmin diagrams make better arguments with those diagrams. My paper was actually a ‘Modest Proposal for Annotating the Dialectical State’ and literary tradition required that such a paper be ironic or satirical, even humorous in the face of serious circumstances (Swift, 1996). So I suggested, whimsically, that the boxes and arrows and recursive structure of argument graphs could be replaced by a single historical image: the face of a political candidate, or a civil war general, perhaps even a football quarterback. Throw out all the rigid logical form, I wrote tongue-in-cheek, and use Barack Obama’s face for a new and untested argument of great popular force, or George W. Bush’s face for an old argument that has gotten progressively more difficult to make and which began on dubious grounds anyway. It was not such a bad idea: replace the Microsoft Windows style summaries that use plus and minus signs (or red and green lights) with a richer set of ‘emoticons.’ Some arguments get a plus sign, or a green light, when many