The following is from: 

"Improving Students’ Evaluation of Informal Arguments"

The question for Teachers: 

Can students distinguish structurally acceptable arguments from unacceptable arguments?

The first place teachers and most effective arguers will look is to 

the WARRANT of your central claim.

Brief Tutorial on WARRANTED ARGUMENTS

Three experiments were conducted to assess students’ ability to distinguish structurally acceptable arguments from unacceptable arguments, and to test the effectiveness of instructional interventions. In these experiments, participants evaluated the quality of items that were either complete arguments (claim-reason pairs), unsupported claims (no reason), or unwarranted arguments (reason does not support claim). We found that without an argument tutorial, both high school and college students frequently failed to distinguish acceptable arguments from structurally flawed arguments. (No surprise there!)

RATIONALE: 

"The ability to evaluate arguments is a fundamental aspect of social interaction and human decision making. Argumentation skills are also important in academic endeavors. Students in the humanities are expected to analyze arguments presented in texts and present a reasoned analysis of that information (National Center for History in the Schools, 1996). In the sciences, argumentation skills can help students acquire knowledge (Driver, Newton, & Osborne, 2000; Schwarz, Neuman, Gil, & Iiya, 2003;Zohar & Nemet, 2002), and it is central to hypothesis testing; that is, students need to be able to determine whether empirical evidence provides support for a stated claim (e.g. Duschl, 2000; Kuhn, 1993; Lawson, 2003; Lederman, 1992). Argumentation skills are also required for professional training as indicated by its inclusion on most entrance exams (e.g., SAT, GRE, LSAT, and MCAT).

Although current standards assume that students become skilled in argumentation during their schooling, many students leave high school unable to understand, evaluate, or write arguments (National Assessment of Educational Progress, 1996, National Assessment of Educational Progress, 1998, National Science Board, 2006). Students also seem to have special difficulty with scientific arguments. Perkins, Farady, and Bushey (1991) and Kuhn (1991)have concluded that these failings may be a result of a lack of exposure to arguments and explicit instruction and practice in the skills of argumentation.

Although there are several components of argumentation skills, perhaps the most fundamental component is the ability to distinguish warranted from unwarranted arguments. A student who cannot distinguish between a claim supported by a valid reason and one supported by a disassociated reason, or not supported at all, will be able neither to critically analyze arguments nor to produce them with much proficiency.

Testing the Warrant of our Argument Claims is easy enough:

Consider arguments 1a through 1c:

• 1a. People should be allowed to have only two biological children.
• 1b. People should be allowed to have only two biological children because children are small.
• 1c. People should be allowed to have only two biological children because it would help stabilize population growth.

Argument 1a is an unsupported assertion. It does not fit the definition of a minimal argument because it does not have a reason (Toulmin, 1958; Voss & Means, 1991).

Argument 1b also does not have the structure of a minimal argument. Although there is a reason provided (i.e., because children are small), the reason does not support the claim. Logically speaking, an argument with an unrelated reason has the same structure as does one that provides no reason. Items such a 1b are referred to as unwarranted arguments because the reason does not warrant the claim.

The final argument, 1c, is a structurally acceptable argument because there is a reason (i.e., because it would help stabilize population growth), and the reason supports the claim. The ability to assess whether a statement meets these minimal requirements of an argument is a necessary step in comprehending, evaluating, and producing arguments. It is also a skill that researchers expect schools to impart to students. As Siegel (1995)argues, “When we say that rationality is a fundamental educational ideal, we are claiming that education ought to strive to foster in students the skills and abilities which will enable them competently to assess reasons” (p. 161).

Simple informal arguments

A minimal argument must have a claim that is supported by at least one reason. The claim is a statement of belief that is presumed to be open to debate, thus requiring support.

For example: “handguns should be banned” is the basic claim or a proposal argument, that a student supports with reasons (based on consequences):  Handguns encourage criminal behavior; therefore, handguns should be banned.

The reason in Argument 2 is “handguns encourage criminal behavior.” For the argument to be well structured, the reason must support, or lend credence to, the claim through an implicit or explicit inference from another, already accepted belief. One such inference is the warrant. Warrants are unstated assumptions that arguer assumes are already acceptable to the audience (Toulmin, 1958). For example, the unstated warrant for Argument 2 is something like “the government should prohibit things that encourage criminal behavior.”

The warrant

Philosophers since Aristotle have proposed that informal arguments (e.g., Argument 2) require the reader to supply unstated information to form a complete argument. According to Aristotle, “The enthymeme must consist of a few propositions, fewer often than those which make up the normal syllogism. For if any of these propositions is a familiar fact, there is no need even to mention it; the hearer adds it himself” (1973, p 735). This corroborates Grice’s maxim of Quantity: Speakers should state what is required, but no more, to make one’s point understood (Grice, 1975). The most common unstated element in these informal arguments is the warrant. It is “a general, hypothetical statement, which can act as a bridge, and authorize the sort of step to which a particular argument commits us” (Toulmin, 1958, p 98).

Although there is some disagreement over the exact form of argument warrants (Mans & Preyer, 1999;Grennan, 1997; Levi, 1995), it is clear that the reason must support the claim if it is to form a well-structured argument. For example, the claim “handguns should be banned” can be supported by the reason in 3a but not by the reason in 3b:

• 3a. Handguns encourage criminal behavior, so handguns should be banned.
• 3b. Ninety percent of handgun purchases are now subject to instant FBI criminal background checks, so handguns should be banned.

To represent each of these arguments, readers must form a claim-reason connection and test whether that connection is warranted (i.e., the reason provides relevant support for the claim). Skilled readers of arguments need to be able to appreciate the differences among arguments such as 1a–1c and 3a–3b in terms of strength and acceptability.

Blair & Johnson (1987) have proposed a set of criteria that are required of argument premises. These include acceptability (the truth status of the premises), relevance (whether the reason warrants the conclusion), and sufficiency (whether the reason provides enough evidence considering everything known). Although students’ skill at considering each of these elements is important, the present research focuses on relevance.

Role of claim predicates in determining relevance

The claim of any argument can be decomposed into various components, the most important of which are the theme and predicate. The theme is the topic of the argument, such as “cell phone use,” “marijuana use,” or “car insurance rates.” In claims 4a–4c, the theme is “government regulation of tobacco companies.” The predicate refers to the main verb or predicate adjective in the claim. Claims 4a–4c differ with respect to the predicate asserted: “sued,” “was right to sue,” and “should sue.”

• 4a. The government recently sued the tobacco companies. (STATEMENT)
• 4b. The government was right to sue the tobacco companies. (EVALUATION CLAIM)
• 4c. The government should sue the tobacco companies. (PROPOSAL CLAIM)

Differences among predicates can drastically alter the intent or STASIS of the argument with a change of only a few words, as demonstrated in examples 4a–4c. Factual or causal predicates, such as 4a, assert that a state of affairs existed, exists, will exist, or caused something else to exist (e.g., “sued,” “will sue,” “sued because”); These types of claims are common in science and are intended, primarily, to change a belief. Value predicates, such as 4b, assert that some action or state is valuable, desirable, or moral, thus makes an evaluation...(e.g., “was right to sue,” “is unfair to sue,” “needed to sue”). The goal of value claims is to change a belief or attitude.  Policy predicates, such as 4c, assert a proposal about the need or favorability of  a change (e.g., “should sue,” “should not be allowed to sue,” “should encourage suing”). They are frequently used to argue for a particular course of action or solution to a problem.