A pressing problem for proponents of the existence of visual arguments-arguments presented at least partially in a visual mode--concerns what evaluative method or methods are available for the assessment of such beasts. Specifically, can visual arguments be evaluated in the same ways as verbal arguments, or are unique methods, standards, and criteria required? In this paper, I urge the use of argumentation schemes, as presented by Walton, Reed, and Macagno (2008) as a method for handling this normative task.
Part of the power of argumentation schemes is their versatility. Schemes categorize very general features of argument types. Hence, individual schemes are applicable to a wide range of arguments within given categories. It does not matter if, say, an analogical argument has multiple sentences regarding comparison, the scheme applies. Moreover, as no list of schemes should be thought to be exhaustive, it is possible to recognize new schemes. This is an important move when no existing scheme seems applicable, which may be the case with many visual arguments.
In applying schemes to arguments containing visual content, one may need to take advantage of the versatility of recognized schemes or invent new schemes depending on the case. I demonstrate this with examples. In one case, I show that an existing scheme, slippery slope, applies straightforwardly to a visual example. In another, I develop a new scheme to account for a typically, though not necessarily, visual argument pattern-what I call an argument from fit. In both cases, the normative legitimacy of the method is explained in exactly the same way. Both schemes identify features of the text or image that are essential to the reasoning as conveyed. Next, through critical questions, the schemes identify typical ways in which the reasoning could fail. In this way, the schemes (whether visual or verbal) function as tools for appraisal by testing typical ways in which the evaluative criteria of relevancy, sufficiency, and acceptability fail to be met in reasoning of some recognizable pattern.
This essay starts by discussing argumentation schemes and their application to verbal arguments. I explain briefly both the theory and value of schemes as tools of argument appraisal. Next, I discuss a definition of visual argument. In that section, I address several common concerns regarding the existence of visual argument. Of course, the goal is not to settle the issue, but to show that at least some of the worries regarding the existence of visual argument are specious. The important result of this section is to note that whatever visual arguments are, on at least the construal asserted here, they have the usual structure of arguments generally, viz., premises and conclusions. Then I apply a typically verbal scheme to a visual example. The point here is to demonstrate the naturalness or ease of applying schemes to a visual example. The appraisal works whether the argument is verbal or visual. In the next section, I address an apparent case of visual argument to which no extant scheme seems applicable. Thus, I suggest a remedy in the form of a new scheme. Finally, in the conclusion, I suggest potential future developments.
WHAT ARE ARGUMENTATION SCHEMES?
Judging by the chapter in Walton, Reed, and Macagno (2008), the history of argumentation schemes is long. Schemes date at least to the time of Aristotle. Schemes classify particular forms or patterns of reasoning--identifying premise types, for example--and pose critical questions that apply normative pressure to typical ways in which inferences may fail. There can be schemes for common deductive patterns such as eliminating alternatives (also known as disjunctive syllogism), common inductive patterns like generalization from a sample, and common presumptive patterns such as appeal to authority.
This essay remains faithful to the presentations of Walton (1996) and Walton et al. (2008). Thus, a scheme contains two components. First, there are the analytical elements. Each premise and conclusion type involved in a particular pattern is listed and given a standard paraphrase. Second, there are the evaluative components. These are critical questions. Critical questions apply normative pressure that reflects the standard ways that arguments might fail. Insofar as the premises, conclusion, and inference withstand this normative pressure, the argument is judged, at least provisionally, successful. Walton et al. (2008) offered the following scheme:
ARGUMENT FROM POSITION TO KNOW
Major Premise: Source a is in position to know about things in a certain subject domain S containing proposition A.
Minor Premise: a asserts that A is true (false).
Conclusion: A is true (false).
CQ1: Is a in position to know whether A is true (false)?
CQ2: Is a an honest (trustworthy, reliable) source?
CQ3: Did a assert that A is true (false)? (p. 309)
The pattern of inference is familiar enough. The scheme partially formalizes the components by naming the premises and providing generic and archetypical paraphrases for premises and conclusions. The critical questions apply normative pressures that reflect the unique features of arguments of this type. CQ1 and CQ3 challenge the acceptability of the major premise and the minor premise respectively. CQ2 challenges the sufficiency of the premises for the conclusion. A negative answer to any of the questions would probably be sufficient to defeat the argument. For example, having an obstructed view rebuts the notion that the source was in a position to know. An ambiguous statement in the minor premise raises questions about whether the source asserted what is under consideration, etc. So, whereas the premise/conclusion/inference section articulates the analytic enterprise of argument assessment, the posing and answering of critical questions articulates the evaluative enterprise. Together, these elements comprise an initial assessment of an argument of the relevant schematic type at a given time or in a given context.
As an application of the scheme to a not-so-serious, but nevertheless actual, example, consider a common fact-finding mission in my life. I often ask, perhaps to no one in particular, "How did this--get broken?" Occasionally, I get the following response: "I [kid-one] was right there when--was broken. It was [the other kid]." From this reply, I might construct an argument with the form of position to know.
Major Premise: Source a, kid-one, was in a position to know how--was broken.
Minor Premise. Kid-one said that it was the other kid.
Conclusion: The other kid broke--.
Though I might grant that kid-one was in a position to know about the breakage (by answering [CQ.sub.1] affirmatively) and that kid-one explicitly asserted the conclusion (by answering [CQ.sub.3] affirmatively), kid-one is generally not an honest source when it comes to broken things. That means I should give a negative answer to CQ2. Hence, I would reject this argument until or unless I get corroborating evidence for the claim. This negative result (i.e., rejecting the argument) is not a simple function of the assessment being negative. In the cases of what Walton (1996) and Walton et al. (2008) called presumptive schemes, even positive appraisals are open to future rejection if and when new and relevant evidence becomes available to defeat or renew the argument.
Before applying a scheme to a visual argument, I need a working definition for the concept. Groarke (2003) offered a promising start:
[A] visual argument is an argument conveyed by (non-verbal) visual means. One can find visual arguments that contain no verbal elements, but most combine the visual and the verbal. In some cases, a visual argument makes the same claims both visually and verbally, reinforcing the verbal with the visual (or the visual with the verbal). More frequently, the visual and the verbal contribute different elements that combine to create an argument, (p. 1)
Several elements of this description need comment. First, whatever the appropriate account of argument, in this case the focus is on...