Structures of Argument


Now that we've looked a bit at the Toulmin schema, we can move on to exploring how arguments may be put together in various ways. For arguments which need to be analyzed beyond the basic claim-evidence-warrant structure, we need still another apparatus to help us analyze what a rhetor is doing when advancing an argument. How does each bit of evidence (which, in more complex structures, may be considered a claim in its own right) relate to the other and to the larger, central claim (called a thesis)? What might this relationship mean about the available evidence for the thesis, and what might the structure of an argument say about the state of our knowledge about a given matter
and within a given discourse community? These and other questions are important to consider when we are reading and composing arguments.

Let's consider these three structures of argument.


Series Structure


The series structure is so called because, like the lights in a series circuit, if one fails, all fail. An argument which is aligned in a series structure must be solid at all points in its major claims, or else the entire argument will come undone. As David Zarefsky notes, this is a risky structure on which to base one's arguments, but if the links between each of the major claims hold, then one has a very strong "momentum" that is difficult to argue against.

Evidence —> Evidence —> Evidence —> Claim

One fails:

Evidence —> Evidence —> Evidence —> Claim

All fail:

Evidence —> Evidence —> Evidence —> Claim


Parallel Structure


Like the series structure, the parallel structure derives its name from electricity because of its analogous relationship to parallel circuits. If one argument
fails, the others will not, on that account, "go out." This is a very common form many arguments take. How do you spot a parallel structure? Here's one clue. You may be dealing with a parallel argument when you read one point and agree while disagreeing with another and do not find the other point with which you agree therefore any less compelling, considered alone. The upside of an argument so structured is obvious: whereas critics may "knock down" a claim here or there, the entire argument is not necessarily refuted, even if it is, on the whole, somewhat weakened. In other words, it doesn't shine as brightly, but it's still shining.

Evidence —>
Evidence —> Claim
Evidence —>
Evidence —>

One fails:

Evidence —>
Evidence —> Claim
Evidence —>
Evidence —>

The rest may hold:

Evidence —>
Evidence —> Claim
Evidence —>
Evidence —>


Convergent structure


In this structure, the effect is what David Zarefsky calls "cumulative." He explains that any one piece of evidence would not, by itself, lend any high degree of probability to the claim being established. Sometimes, we simply cannot find evidence which will do this. We can, however, marshal evidence which, taken together—taken cumulatively—will add significant weight to the thesis. That is, all of the evidence "converges" to lend support to the argument. One of the simplest examples I can think of is this: "It walks like a duck. It talks like a duck. It looks like a duck. Therefore, it's a duck." You can see that none of these bits of evidence, alone, would be enough to establish that what we're considering is, in fact, a duck. But when considered all together, we see that the claim is more difficult to dismiss.


Convergent_structure.jpg




Source Consulted

Zarefsky, David. Argumentation: The Study of Effective Reasoning. 2nd Edition. Chantilly, VA: The Teaching Company, 2005.