Claim, reason, evidence: how arguments earn trust

In one minute

A claim is what you want believed. A reason says why it follows. Evidence is what someone else could check. Arguments lose trust when the middle term is missing — the evidence is there, but nothing says what it proves.

Why it matters

Argumentation research and school curricula converge on this three-part shape because it makes the weak joint visible. Most unconvincing arguments are not short of evidence; they are short of the sentence explaining why that evidence supports that claim.

• A claim with no reason is an assertion.
• A reason with no evidence is an opinion.
• Evidence with no claim is a pile of facts the reader must interpret alone.

See it

The rewrite supplies the reason connecting the measurement to the recommendation.

Try it

Take your strongest claim and write “because…” after it. Then ask what someone sceptical would want to see before accepting that “because”.

When not to use it

Shared premises do not need re-proving. Restating what your reader already accepts reads as padding, or as doubt about their expertise.

How SeamWriter notices it

SeamWriter can see a conclusion-shaped section with no linked source and say so. It cannot judge whether a source is good, whether it supports the claim, or whether a claim needed support at all. The judgement stays yours.

For different writers

Learning to write

Three questions, in order: What do I think? Why do I think it? How do I know? Write all three, even if the last one is “I noticed it in chapter two”.

Writing fiction

The same joint appears in fiction as motivation. A character’s decision is the claim; what they know and want is the reason.