A previous post in this blog discusses the risk in leaving some premises implicit in an argument map. This post uses another example drawn from Austhink Consulting’s recent report to help illustrate this risk. (I use this report because it is one of the finest examples of the power of argument mapping.)

The argument maps in the report were created with Rationale™ software using the typical argument mapping visual language (i.e., pyramid). The graphical conventions of pyramid permit implicit inferential premises. This lack of strict scaffolding permits an argument pyramid to be inadvertently designed with a faulty structure.

In contrast, an argument map created with Rationale™ using path does not permit an argument with a faulty structure. The reason is that path relies upon an interlocking premise structure that cannot be built with implicit inferential premises. This structure uses an inference method called “argument essential predication transitivity” ( ADEPT™ ). In litigation using a reasoning process that reduces risk of error is a sound decision.

A portion of Austhink Consulting’s argument mapping is shown below.  p. 45.                                    
                                         

An application of the no danglers rule indicates that the terms “combat weight” and “sound decision” are danglers. This is a clue that there might be a problem. Trying to fit the premises into a path structure illuminates the problem.

The first step is to shift to a left-to-right orientation and place first in order the premise whose subject is the same as the subject of the main conclusion.

The next step is to insert the predicate of the main conclusion as the predicate of the second inferential premise and to make space for the interlocking subject of that second inferential premise.

The next step is to insert the subject of the second inferential premise as an appropriate transitive match for the predicate of the first inferential premise.

This process reveals that, as structured in the Austhink Consulting report, premise 1A-a, as shown in the first map above, does not link or connect the other premise to the main conclusion. The two premises do not work together. This is a flaw in the reasoning structure as depicted in the argument map in the report.

This flaw in visual representation comes at a critical point in the argument. The reason is that the “pivotal claim” intended to be represented is “that maintaining the tank capability was necessary if our Army was to have the ‘combat weight’ to achieve its mission without undue risk.” p. 44. The following path map illustrates one possible correct version of the inferential relationships as indicated by the narrative. The path map below could be translated back into a pyramid map by adding redundant premises.

As this layer of the pyramid map is corrected, every layer beneath it will also need adjustment so that each premise acting as support is properly worded and placed correctly in the inferential network.

The above process was performed to illustrate the nature of using argument maps in litigation. Litigation is about two adversaries engaged in conflict with the goal of each of the parties to persuade the judge or jury. This context necessitates that in preparing a trial exhibit every single element be tested for an anticipated attack intended to reduce its credibility. Of course, in litigation, the opposing party then has an opportunity to show how that effort was itself flawed. Unlike in litigation, I always welcome such replies in this collegial atmosphere since understanding, not winning, is the goal. This process of ongoing critical examination will, hopefully, advance the art of argument mapping to everyone’s benefit.