Evidence never speaks for itself. Between a piece of evidence and the claim it supports lies an unstated assumption — the reasoning, or warrant, that makes the evidence count. Miss the reasoning and you miss where most arguments are actually won or lost.
The warrant: the hidden hinge
Suppose a writer argues: “Crime fell after the streetlights went in (evidence), so the town should light the east side too (claim).” The evidence does not reach the claim on its own. It relies on an unstated assumption — that the lights caused the drop, and that the east side is similar enough for the same fix to work. That assumption is the warrant.
Naming the warrant is powerful because a warrant can be true or shaky. If crime was falling everywhere that year, the warrant (“lights caused it”) is weak, and the whole argument sags — even though the evidence is a true fact.
[Diagram — see the figure in the print workbook.]
Lines of reasoning
Zoom out from a single warrant and you see the line of reasoning: the ordered chain of sub-claims that carries a reader from where they start to where the writer wants them. A strong line of reasoning has no gap a skeptic can step into; a weak one leaps.
When the exam asks about a passage's “line of reasoning,” it wants the logical route, not a summary. Trace the steps: the writer establishes X, uses it to grant Y, and only then claims Z.
Worked example 1
State the warrant this argument depends on, and judge whether it holds.
On Buying a Bigger Phone — Original passage for this workbook
Last year I solved my “storage full” warnings by buying a phone with twice the memory. Within four months the new phone was as full as the old one had ever been, because a roomy phone quietly invited me to keep every photo, app, and video I once would have deleted. So do not tell me the answer to a cluttered device is simply more space. More space will not cure the clutter. It will only feed it.
Evidence: doubling the phone's memory did not relieve the “storage full” problem for long. Claim: buying more storage will fail to cure clutter the same way next time.
Warrant: the added space causes the same behavior (keeping everything) that filled the last phone — an “induced demand” effect, where new capacity generates new consumption. Does it hold? Fairly well: the writer names a mechanism (a roomy phone “invited” keeping more), which is stronger than mere coincidence. A skeptic's opening is to argue that a disciplined user, or one who turns on auto-cleanup, would not refill the space — the passage treats one person's habit as if it were a law.
Common trap: A true fact can support a false step
The evidence can be perfectly true and the argument still broken, because the reasoning connecting it to the claim is faulty. This is why “but that fact is true!” is not a defense of an argument. The exam rewards students who evaluate the link, not just the facts.
Whenever an argument moves from “A happened, then B happened” to “A caused B,” slow down — that is a warrant, and it is often the weakest board in the bridge.
Hack: Say the 'because' out loud
To surface a hidden warrant, connect the evidence and claim with the word because and finish the sentence: “More storage won't cure the clutter because ______.” Whatever you have to add to make the sentence true is the warrant.
Once it is out in the open, you can judge it. Half of “evaluate the argument” questions are really asking: is the because true?
