Claim, evidence and warrant
An argument tries to make you believe something. It has three parts.
- Claim: what we want you to believe. "It rained last night."
- Evidence: the proof we start from. "The school ground is wet."
- Warrant: the rule that links the proof to the claim. "Wet ground usually means rain."
The warrant is often not said aloud. The writer thinks it is obvious. A careful reader finds it and asks if it is really true.
Evidence: what it is and how to test it
Evidence can be a fact, a number, an example, a photo, or the words of an expert. Test it with three questions.
- Is it true? Can you check it? Who says it, and how do they know?
- Is it enough? One wet patch is not the whole ground. A small survey of 5 people is not "everyone".
- Is it relevant? Does it speak about the claim? Marks in maths do not prove a student writes well.
Also ask: is the evidence recent, and is it fair (not picked only because it suits the writer)?
Warrant: the hidden bridge
A warrant says "when we see this, we may conclude that". To find it, fill this sentence: "Because ___, we may say ___."
Example: Evidence: "Ravi scored 95 in the test." Claim: "Ravi is hard-working." Warrant: "People who score high work hard." Is that always so? No. Some students learn fast without long hours. The warrant is not safe.
Common kinds of warrants
- Cause: this event leads to that event.
- Sign: this thing usually shows that thing.
- Example to rule: what is true of some is true of all.
- Expert: this person knows, so believe them.
Judging validity
An argument is valid (works well) when the evidence is good and the warrant is safe, so the claim is believable. Use this check:
- Find the claim.
- Find the evidence and test it (true, enough, relevant).
- Find the warrant and test it (usually right? common exceptions?).
- Decide how strong the claim is: sure, likely, possible or weak.
Words like always and proves need very strong evidence. Words like probably and suggests are fairer when evidence is thin.
Try it
Take a news headline or an advert. Write its claim, its evidence and the hidden warrant. Give each of the evidence and the warrant a score from 0 to 3. Does the claim stand?
Key formulas and definitions
- Argument = Claim + Evidence + Warrant
- Test the evidence: true? enough? relevant?
- Find the warrant: "Because ___, we may say ___."
- Test the warrant: usually right? common exceptions?
- Key term, warrant: the rule linking evidence to claim
Worked examples
1. Claim: "This shop is the best in town." Evidence: "It has the longest queue." Find the warrant and test it.
Warrant: "A longer queue means a better shop." Test: the queue may be long because the shop is slow or the only one nearby. The warrant has exceptions, so the claim is only possible.
2. Evidence: "In our class, 3 of the 4 students I asked like the new timetable." Claim: "The whole school likes the new timetable." Which test fails?
Enough fails. Four students are too few and only from one class. The evidence is true and relevant but not enough for "the whole school".
3. Claim: "Cycling to school makes children fit." Evidence: "A study of 500 children in 10 schools found cyclists ran faster." Test both parts.
Evidence: true (a named study), enough (500 children, 10 schools), relevant (fitness by running). Warrant: "cyclists run faster because cycling builds fitness." Fit children may also choose to cycle. So the claim is likely, not certain.
Common mistakes
- Looking only at the evidence and never asking about the link between evidence and claim.
- Thinking a true fact makes the whole argument good. A true fact can lead to a wrong claim.
- Accepting a small sample (a few people) as proof for "everyone".
- Missing the warrant because it is not written. It is often hidden, so look for it.