Critical Thinking · Lesson 1 of 4

Claims, evidence and sources

For any claim worth acting on, write down what evidence would settle it. Often the answer is "none available", and that is the finding.

6 min read · Free — no account needed to read

A claim is a statement that could be true or false. "This course is the best way to learn design" is a claim. "I enjoyed this course" is a report of experience. Telling them apart matters, because only the first one owes you evidence.

Evidence is what would let a stranger reach the same conclusion without trusting you. Strong evidence is specific, was gathered in a way that could have produced a different result, and comes from somewhere that would have published the opposite finding just as readily.

The source matters as much as the content. Ask three things: how would this person know, what happens to them if the claim is wrong, and who would have said something if it were false. A claim with no one positioned to contradict it has not survived a test — it has just not been tested.

See it happen

"The fastest way to learn design" — on a course page with 400 five-star reviews and an instructor from a studio you recognise.

The read that arrives on its own

The reviews are overwhelming and the instructor is real. This is probably the one.

The same situation, with this idea

Fastest compared with what, measured how, over what period? The reviews are all from people who finished. Where are the ones who stopped in week two, and who was ever going to publish that?

What changed

The claim has not survived a test — it has just never been contradicted, because everyone in the sample is someone it worked for.

The takeaway

For any claim worth acting on, write down what evidence would settle it. Often the answer is "none available", and that is the finding.

Easy to take the wrong way

Treating "no evidence either way" as a reason to believe it. That absence is the finding, and it usually means the claim should carry less weight, not the same.

Try this

Take a claim you read online this week. Write the one piece of evidence that would change your mind about it.