  One influential approach to assessing the "goodness" of arguments is offered
by the Pragma-Dialectical school (p-d) (Eemeren & Grootendorst 1992). This can
be compared with Rhetorical Structure Theory (RST) (Mann & Thompson 1988), an
approach that originates in discourse analysis. In p-d terms an argument is
good if it avoids committing a fallacy, whereas in RST terms an argument is
good if it is coherent. RST has been criticised (Snoeck Henkemans 1997) for
providing only a partially functional account of argument, and similar
criticisms have been raised in the Natural Language Generation (NLG)
community-particularly by Moore & Pollack (1992)- with regards to its account
of intentionality in text in general. Mann and Thompson themselves note that
although RST can be successfully applied to a wide range of texts from diverse
domains, it fails to characterise some types of text, most notably legal
contracts. There is ongoing research in the Artificial Intelligence and Law
community exploring the potential for providing electronic support to contract
negotiators, focusing on long-term, complex engineering agreements (see for
example Daskalopulu & Sergot 1997). This paper provides a brief introduction to
RST and illustrates its shortcomings with respect to contractual text. An
alternative approach for modelling argument structure is presented which not
only caters for contractual text, but also overcomes the aforementioned
limitations of RST.
