Stephen Toulmin

When Toulmin was still a graduate student at Cambridge Univeristy, he became interested in the nature of rationality. He asked himself if "intelligent fish learned science, . . . must they in the long run end up with the same body of ideas as human beings?" Toulmin started out with more of a philosophical approach to rationality. It wasn't until his later work that he started to see the importance of rhetoric to philosophy.

In in book The Uses of Arguments he introduces two types of arguments: substantial and analytic. The conclusion of a substantial argument involves a leap from some sort of data or evidence. Unlike substantial, analytic requires no leap because the conclusion is still based around the argument of the premises. Those who use analytic arguments focus on unchanging claims. Ones who use substantial arguments take their claims and place them in a particular situation. The terms substantial and analytic are discussed again in a book by Jonsen and Toulmin. In the book they refer to analytic as theoretical arguments and substantial arguments are practical.

Between the two types of arguments that Toulmin presented, I would think that substantial arguments have the greater affect. Substantial arguments actually place the principles being discussed in particular situations. They also discuss probability of such circumstances. Substantial arguments don't just rely on facts and numbers. The audience being spoken to would probably get more out of a substantial argument than they would an analytic argument.