Teaching Toulmin Argumentation

In previous posts I have argued that argument is a part of persuasion and that Aristotle’s three appeals (ethos, logos, pathos) and the Toulmin model are, in fact, compatible in that they are alternative solutions to the same problem: most audiences are unwilling or unable to follow long chains of logical reasoning. In this post, I want to discuss teaching the Toulmin model in greater detail.

Toulmin’s model is often presented as a list:

  • Claim—an assertion.
  • Data—evidence, i.e. facts which support the assertion.
  • Warrant—justification for a connection between data and claim, i.e. a rule, principle,or pattern.
  • Backing—principles or body of knowledge that lie behind the warrant, usually belonging to a discipline or field of endeavor.
  • Qualifiers and Rebuttal–conditions, exceptions, qualifications to the claim.

The model is dialogic. We have to imagine an assertor and a questioner. When a claim is made, and questioned, the assertor will produce data or evidence. If the evidence is challenged, not in terms of its facticity, but in terms of its relevance, a warrant will be produced to connect data and claim. If the warrant is challenged, the assertor refers to a body of knowledge, a system of principles or accepted wisdom, or disciplinary practices, to give backing to the warrant.

In explaining his model, Toulmin imagines the claim “Harry was born in Bermuda so he is a British subject.” If the questioner asks, “How do you know?” the warrant is “People who are born in Bermuda are British subjects.” If the questioner asks further, “Why is that so?” the backing for the warrant will refer to particular statutes in British law. Of course, Harry might have become an American citizen through naturalization. Thus, qualifications and possibilities of rebuttal are built into the system as well (Uses, 93-95).

It all seems simple and useful, a handful of terms that have great explanatory power. However, the model was clearly designed as a tool for analyzing arguments, not creating them. Can it also be used as a heuristic for helping writers generate valid arguments? And if so, what is the best way to teach it?


The first step is recognizing when a claim is being made. In Rhetoric of Reason, James Crosswhite notes that recognizing a claim is not a trivial act.

Every teacher knows how profoundly difficult it is for some students to locate the claims a writer is making. The challenge in such instances is to help to make the claim come to life as a claim for a person who cannot hear a claim’s being made. The person who cannot hear a claim’s being made in a piece of writing is in an important respect insensible to writing as writing. The problem is that the unclaimed reader has not questioned the writing in a way that would allow the claim to come forth as a claim. Until an assertion is understood as something questionable, its being a claim stays closed off to us. (Crosswhite, 90)

We should also note that unless a claim is questioned, in this model of argumentation, there is no call for evidence. In many circumstances, a claim such as “Harry is a British citizen,” would simply be accepted as fact. Whether or not a reader questions a claim depends on many factors, including the ethos and authority of the person making the claim and the habits of mind of the reader. For many students, the mere fact that an article has been printed in a book or newspaper gives it such authority that the claims it makes are accepted without question.

The first step, then, is to work on recognizing claims and looking for evidence. Will giving the students all the terms in the whole model at once in a list or chart help them recognize claims? Or will it shut down the process of recognizing claims too early?


If many claims go unquestioned, it is even rarer in public discourse that someone requests what Toulmin calls a “warrant”: a clear explanation of the connection between the claim and the evidence that is offered to support it. A scientific paper that asks a research question, proposes a methodology, presents data, and draws conclusions from that data, might spend considerable time discussing the connection between the data and the conclusions. In fact, if the project is groundbreaking work, the “warrants” might be the most important substance of the paper. However, whether such warrants are requested has much to do with the relationship between the writer and the reader. If the writer and the intended audience are part of the same discipline engaging in similar work, the connections may be obvious and go unquestioned.

If we imagine a student trying to provide evidence to support a thesis statement, does the concept of “warrant” help students discover such evidence? Does it help them evaluate the ideas they come up with? What passes for evidence in most school essays is inductive examples. Will students be able to use the concept of “warrant” to discern the weak connection between their claim and the evidence?


For lawyers, the backing is the law. For physicists, it is the laws of physics and the discipline itself. In most cases, if the backing is questioned, the argument is in real trouble. This is probably most common in cases where someone in a discipline or professional field is making a claim to someone outside that field. The debate over climate change is a good example. Perhaps 97% of climate scientists make two claims: 1) The Earth is warming. 2) The warming is caused by human activity. If we challenge those claims, scientists will present large amounts of data of various types as grounds for their claims. If we question the connection between the grounds and the claim, as warrants they will present climate models and historical events. If we question the warrants, they will fall back first on their discipline and finally on science itself, as backing. Climate change deniers question the validity of science itself, either by saying that the scientists have ulterior motives and thus their disciplines are corrupt or by saying that science itself is irrelevant because it is all in God’s hands. Either way, the questioning has gone beyond backing and thus beyond Toulmin.


The Toulmin model is simple, elegant, and useful. It was designed to analyze arguments and is probably best used to locate where an argument is being challenged and what might be done in response. Students need to practice recognizing and challenging claims in real world texts before they begin applying these concepts to their own writing. And when they do apply them, they need to imagine the questioning reader implied by the model and anticipate questions about warrants and backing.

The question I have been hinting at from the beginning of this post is “When does a heuristic become an obstacle?” The Toulmin diagram looks like it is representing the necessary parts of an argument. However, what is actually happening is that each term drills into a different layer of social organization, from an individual questioner (evidence), to common sense and shared rules (warrants), to entire disciplines and practices (backing). As a heuristic, it generates epistemological questions about audiences and discourse communities, not logical pieces of an argument. If teachers present the model to students as a parts schematic when it is really something very different, students will become confused, especially if the model is presented as fill-in-the-blanks instructions for making an argument.

What is also very clear about this model is that it is rhetorical. The validity of an argument depends not on a reference to absolute truth, but to a socially-situated body of knowledge and practices which Toulmin calls “backing.” In actual practice, whether a claim is questioned at any level depends as much on the relationship of the person making the claim and the audience than on anything else.

In this post, I have not dealt with qualifications and rebuttals, another interesting part of this model.  I will save that for a future post.

Works Cited

Crosswhite James.  The Rhetoric of Reason: Writing and the Attractions of Argument. Madison: Univ. of Wisconsin Press, 1996.

Toulmin, Stephen E.  The Uses of Argument. Updated Ed. Cambridge: Cambridge Univ. Press, 2003.

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