Why Assumptions Matter
A clear sense of what is taken for granted is a powerful tool for understanding any kind of communication, including texts. It also underscores the need for you to understand writing in context. Surfacing the implicit, unspoken ideas in writing and working through their implications are central to understanding and working with written arguments.
If claims do not have explicitly stated grounds, what does the arguer seem to be taking for granted that their audience will already accept or fill in on their own? A clear sense of what is taken for granted is a powerful tool for understanding what you read and for building your own arguments.
To help us to understand assumptions, Toulmin emphasized the concept of the warrant, which we can think of as a specific kind of assumption because it is usually left implicit in real arguments.
Think of the word "warrant" as "authorization," such as a search warrant that authorizes the police to conduct a search. In the sense Toulmin used it, the warrant is the "bridge" that authorizes the movement from grounds to a claim. It shows why the grounds support the claim.
We know that the grounds are intended to support the claim (they are the "because" being offered), but the warrant is the underlying assumption or principle that (at least in the arguer's view) makes the leap from grounds to claim reasonable and permissible. This will become less mysterious with a few examples:
This yogurt is unsafe to eat.
It’s past its “sell by” date.
The “sell by” date is a reliable indicator of food safety.
We should amend or repeal the policy.
The policy disproportionately affects low‑income students.
Anything that disproportionately affects low‑income students is unfair.
County officials must issue a boil‑water advisory.
The system’s water pressure dropped below 20 psi.
Pressure below 20 psi often draws harmful contaminants into the water system.
Ms. Rodriguez is an excellent candidate for the XYZ scholarship.
In a college writing course, she earned an A through strong work habits, proactive drafting, use of feedback, and revisions.
Those habits demonstrate the diligence and mindset that scholarships aim to support.
Notice how the warrant might be simple or, in the case of last example, more complex since it might be necessary to make another argument about the grounds for reasonably asserting that pressure below 20 psi often draws contaminants into the water system, and that those contaminants are actually harmful. But the main thing to focus on in understanding and building arguments is to try to draw out and make explicit what is usually not stated outright: "Why do these grounds support this claim?"
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