What is a warrant?
"Toulmin derives his term warrant from the concept of "warranty" or "guarantee." The warrant is the value, belief, or principle that the audience has to hold if the soundness of the argument is to be guaranteed or warranted. The warrant - once accepted by the audience - "guarantees" the soundness of the argument. Sometimes in an argument, the warrant is not stated." (Ramage, Bean, and Johnson, 76)