Drawing Out Our Reasoning

Philosopher Stephen Toulmin

Time to add another critical-thinking technique to your repertoire to help you make sense of a fast-changing world.

So far, the arguments you have been shown on this site have been informal ones consisting of words organized into premises leading to a conclusion. But there are other ways to construct and present arguments that offer a number of advantages over this words-only format, some of them graphical.

One of the most well-known ways to visualize arguments graphically, Toulmin diagrams, was named after the technique’s inventor Stephen Toulmin.

Rather than organize an argument as premises leading to a conclusion, Toulmin diagrams start from Grounds leading to a Claim:

Here’s a contemporary example:

This probably reminds you of the arguments you have seen so far with Grounds serving the role of premises and the Claim serving as the conclusion. But Toulmin diagrams also require you to support the connection between grounds and claim with what is called a Warrant. For example:

You’ve encountered the term warrant before when learning about reasons for belief that connect the premises of an argument to its conclusion. So the first advantage of Toulmin’s method is that those reasons, which might be implied but not stated outright in an informal argument, must be explicitly spelled out and made part of the Toulmin argument diagram.

Another advantage of Toulmin’s method is that it allows you to map out complex arguments that might be made up of several smaller arguments. If we were to try to do this with the kinds of words-only informal arguments you’ve seen so far, this would require creating several smaller arguments, each representing part of the larger compound argument. But Toulmin diagrams can branch out, allowing you to capture multiple sub-arguments in a single diagram.

In the simple example we’ve used so far, this can be done by creating support for the Warrant of our original argument with a new branch:

This new branch provides reasons to believe the original warrant and when we add this branch, the original Warrant is serving “double duty” as the original Warrant as well as the Claim in the new branch that is supported by its own Grounds and Warrant.

There’s more to Toulmin diagrams as well as additional ways to map out complex arguments graphically that we’ll get to in future lessons on logic-checking. But for now, digest what you have learned about this new approach and in a few days I’ll present a new Logic-Checker that analyzes a hot issue of the day using this new technique.