Toulminian logic is such a handy tool. It essentially is a way of looking at the basis for conclusions in all kinds of everyday situations. The framework was designed to evaluate arguments about matters of fact. We're in an era now where a lot of facts get thrown around. If we use facts in a particular manner to back a point of view, Toulmin would point out that we could evaluate the strength of an argument by looking at a number of key elements.

The Geographic Inquiry Model (Palmer, 2002) is dependent on data to answer geographic questions. In fact, it can really benefit from being combined with the Toulminian logic approach. You don't have to, but we think it would strengthen its use in the classroom while providing students with an understanding that they must be cognizant of the quality of the data they use and how they use it.

There's a diagram on this page showing the main parts of Toulmin's structure of argument. As Michael says, the first parts - the data, the inference warrant, and the conclusion constitute the "what" and the implication (that he added on, not Toulmin) is the "so what?"

Using a Toulminian framework reinforces the importance of the issues of quality of the data that provides the information we use in an argument that ultimately influences the quality of our conclusions. It's a fancy way of saying "garbage in, garbage out!" In other words, we can do all sorts of fancy stuff, make things look nice, etc. in our presentations, but if the underlying data we're using to help us make our point is faulty, then everything is faulty.

Here's a more detailed explanation of the terms in the diagram:
Inference Warrant: makes the link explicit between the conclusion and the data that the conclusion is supposed to be based on.

Backing: general background, theory, "customary wisdom" that is the foundation for the inference warrant. Backing can be formal or informal. It can also encompass technical issues, such as measurement accuracy or procedural foundations.

Qualifier: indicates the strength or reliability of the conclusion.

Rebuttal: link to possible counter-arguments. These can have their own inference warrants and backing, and may reflect different theories, procedural standards, etc.