Araucaria as a Tool for Diagramming Arguments in Teaching and Studying Philosophy

This paper explains how to use a new software tool for argument diagramming available free on the Internet, showing especially how it can be used in the classroom to enhance critical thinking in philosophy. The user loads a text file containing an argument into a box on the computer interface, and then creates an argument diagram by dragging lines (representing inferences) from one node (proposition) to another. A key feature is the support for argumentation schemes, common patterns of defeasible reasoning historically know as topics (topoi). Several examples are presented, as well as the results of an experiment in using the system with students in a university classroom. Philosophical writing can be considered a form of argumentative discourse. Such a writer wants to convince her audience of readers or listeners by means of drawing logical inferences and presenting the logical development of her own ideas. Her aim is to provide her readers with reasons to come to accept a conclusion she reaches as reasonable and plausible. In philosophy, as in law and science, there is no indubitable conclusion established by the perfect proof (Descartes to the contrary). An argument for any conclusion needs to be evaluated in the light of the kind and nature of its premises, the strength of the inferential links to the conclusion from these premises, and of its possible criticisms or refutations. The importance of identifying, struc112 ROWE, MACAGNO, REED, AND WALTON turing and representing the components of philosophical and scientific reasoning was recognized by Finocchiaro, who in 1980, in his book Galileo and The Art of Reasoning, described some main passages in Galileo’s arguments by visualizing them through diagrams. There is also a growing body of literature showing that argument diagramming, or “mapping” is being used in the philosophy classroom (Harrell 2005; Powers 2000; van Heuveln 2004), and that it is having a significant effect there (Twardy 2004; Van Gelder and Rizzo 2001). This paper explores a new software tool that supports students in employing features of argument diagramming that are not usually offered by such software, and investigates the tool’s use in the classroom through a simple pilot evaluation study. Araucaria: Main Features Araucaria is a system of argument diagramming based on the Argumentation Markup Language formulated in XML (Reed and Rowe 2001, 2004). It is available at no cost on the Internet. The user can load a text file comprising the text of the discourse, and it will appear in the left-hand box of the Araucaria interface. The nodes of the diagram (indicated by alphabetical letters) are formed by highlighting sections of the argument text with the left button of the mouse and clicking on the right pane. The corresponding text will appear on the bottom line when nodes are selected. Support relationships are then created by dragging a line from one node to another. When the left button is released, an arrow representing the connection will appear. Premises can be arranged in serial, convergent or linked structures, and missing assumptions can be inserted in an enthymeme, marking the inserted text as an unstated premise or conclusion (it appears as a grey node). Araucaria also supports the insertion of refutations: it is possible to represent counter-arguments defeating conclusions or premises. It is also possible to insert an evaluation of a premise in order to indicate its strength, or to mark an inference arrow to show the strength of its support for a conclusion. In the case of refutations, it is possible to compare the force of opposite arguments. Regarding the use of Araucaria diagrams in other programs (such as word processors), not only the summary diagram but also its full text version (including the text corresponding to the nodes) can be visualized and saved as an image. Figure 1 shows what an Araucaria window looks like: In this example, the argument from premises B and C to conclusion A is convergent, whereas the argument from premises F and G to conclusion E is linked. The example shows how arguments are combined to form a chain of argumentation (serial arguments). The so-called divergent argument, in which a single premise supports two different ARAUCARIA AS A TOOL FOR DIAGRAMMING ARGUMENTS 113 conclusions, is not represented in Araucaria. Also, circular arguments are not represented in Araucaria. The argumentation always has the form of a tree structure. Using Araucaria to Enhance Critical Thinking