THE BLOG
12/18/2012 06:30 pm ET Updated Feb 17, 2013

In my previous Huffington Post article, I showed how Aristotelian syllogisms can be used to dissect the argument found in a political ad.

This is done by converting the words that make up the argument into what is called "standard format" consisting of a pair of premises leading to a conclusion. And once an argument is presented in this fashion, we can test it for validity to see if the conclusion leads logically from the premises. And even if the argument is valid, we can still test it for soundness (to determine if the premises hold up their end of the bargain by being true, relevant and sufficient to support the conclusion).

This is an effective method of argument analysis, one that has been used successfully for centuries. But in recent years, a host of new logical systems have emerged which allow us to do things Aristotle's system cannot.

Some of these logics involve complex mathematical systems more suitable for esoteric philosophy or computer programming. But one of them, the Toulmin Model (developed by the British Philosophy Professor Stephen Toulmin) provides a way to analyze what he calls practical or substantial arguments spoken in plain language.

The method involves diagramming an argument in the fashion shown in this illustration.

Under Toulmin, the Claim is an assertion you are trying to prove, the Grounds consist of the information you bring to prove the Claim, and the Warrant supports your assertion that your Grounds should lead you to your Claim. For example, the illustration linked above is based on an argument that goes "The sun is going down so you should put a sweater on." In this argument, the Claim is "you should put a sweater on" and the Grounds are "The sun is going down." And the unstated Warrant (which links the Grounds to the Claim) is that it gets cold when the sun goes down.

On the surface, this might not seem like much of a break from the syllogism. After all, the Claim in the example above looks a lot like the conclusion of a logical argument and the Grounds sound suspiciously like a premise, with the Warrant simply being the "hidden" second premise of the argument. (As an aside, the name Aristotle bestowed an argument with a hidden premise was enthymeme.)

But what makes Toulmin so effective is that the Grounds might consist of facts (as premises often do in a syllogism). But they might be laws, regulations, social customers, literary references, or any other man-made (or even natural) "thing" that can provide support for the Claim. And the Warrant of a Toulmin argument might make a logical connection, but it might also make an emotional or ethical appeal (all equally valid under Toulmin's scheme).

For example, in an argument which says "The National Anthem is playing, so you should take off your hat," the phrase "you should take off your hat" is the Claim and "The National Anthem is playing," the Grounds. But the Warrant linking the two would be an appeal to tradition (the tradition of removing your hat while the National Anthem is playing), rather than a logical connection.

To get a sense of how Toulmin argument maps can help us evaluate the strength of an argument, we will once again reach back to those heady days of a few months back when arguments over Mitt Romney and Bain Capital were generating lots of argument (not to mention lots of dollars for producers of negative ads).

Because this involves a fair number of illustrations that I don't seem to be able to add to a HuffPost piece, you can see a complete analysis of this negative ad here.

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