4 Evidence

Evidence is whatever material can be used to support your claim and reasoning—anything to make it believable, clear or compelling.

For instance, what's the main claim in this ad for Flex TAPE? And what evidence makes it believable, clear or compelling?

Using dot points: What's the main claim in this ad? And what's the evidence?
  • The main claim is that Flex TAPE is a super strong, waterproof tape that can instantly patch, bond, seal, and repair.
  • This is a valuational claim, so it has to match criteria for strong, waterproof, instant, etc.
  • The reason the claim is justified is because Flex TAPE can be slapped over a gushing leak and instantly stop the flow of water (good criteria for a good sealing tape!).
  • The evidence is that Phil Swift shows us. The evidence is Phil slapping Flex TAPE over multiple gushing leaks before our very eyes. In this case, the evidence is a demonstration of the tape's amazing properties.
  • (Phil also demonstrates evidence for other sub-claims, such as the weightlifting to prove the tape's strength.)

(Although, how long does it last? They cut away from the sealed tape quite quickly each time...)

When you're analysing ads, the argument is often very compressed, so you need to fill in a lot of blanks.

When you fill in those blanks, watch that you don't fall into circular reasoning.

For instance, it's easy to look at the Flex TAPE ad and restate the argument as, "This tape is strong because it's strong! And the evidence is that it's strong!" But that doesn't explain anything.

You have to think a little more carefully about each component:

  • Claim: The tape is strong.

That's a valuational claim, which means we need to define criteria for "strong tape".

The reason then needs to describe at least one match to those criteria.

  • Reason: Because the tape can be smacked over a leaking tank and stop the flow.

Without evidence, that reason is just another claim. So the evidence is any material that helps us accept that the reason is true and the claim is justified.

  • Evidence: Phil demonstrates sealing various leaks and lifting weights with the tape.

Ads love compelling evidence so much that they often don't worry if the evidence is "true" in the "reality" sense.

For example, what's the core argument in this ad? And what's the evidence?

Ad showing a carrot on a chopping board that has been sliced all the way through
Using dot points: What's the core argument in this ad? What type of argument is it? What's the evidence?
  • Claim: The WMF Grand Gourmet knife is sharper than you think.
  • Type: That's a factual claim, so we need to match to criteria for "sharper than you think".
  • Reason: Because when you're chopping a carrot, you will slice all the way through your cutting board.
  • Evidence: A photo of the knife with a carrot and a timber cutting board all sliced up.

You might notice that the evidence in the knife ad is not actually true!

This gets back to the idea that, on some level, every statement is a claim that can be contested—and that goes for evidence, too.

Does that mean the Grand Gourmet knife isn't sharp? Or isn't sharper than you think?

Not necessarily! The claim might still be true, but the evidence the ad provides is obviously false.

However, the ad doesn't expect you to take the evidence as true. It's using an absurd, exaggerated scenario and leaving you to separate fact from fiction. ("The Grand Gourmet isn't that sharp, but it could still be surprisingly sharp!")

We said that evidence is whatever material can be used to support your claim and reasoning.

You can use all sorts of material as evidence.

The Flex TAPE ad showed us a video demonstration, while the WMF Grand Gourmet ad gave us a Photoshopped joke.

Could you match those two pieces of evidence to two of the evidence types in this list?

Examples of different types or sources of evidence

  • Personal experience (from yourself and others)
  • Observations (live and recorded)
  • Surveys and questionnaires
  • Published research(from books and articles)
  • Authority opinion & expert testimony
  • Hypothetical scenarios
  • Principle-based reasoning (for more abstract arguments)
What source of evidence (e.g. personal experience, observations, surveys...) did the Flex TAPE ad use? What about the WMF knife ad?
  • Video demonstration is probably an observation. Personal experience is where you've used the tape yourself, whereas observation is where you have seen someone else using it.
  • The visual joke in the knife ad is a fake observation, or maybe you could consider it a kind of hypothetical?

Let's go looking for some more evidence types in the wild.

What types of evidence are used in this snippet?

Myth 1: Cold water is bad for you

Some recent TikToks have suggested cold water causes health problems by somehow “contracting blood vessels” and “restricting digestion”. There is little evidence for this.

While a 2001 study found 51 out of 669 women tested (7.6%) got a headache after drinking cold water, most of them already suffered from migraines and the work hasn’t been repeated since.

Cold drinks were shown to cause discomfort in people with achalasia (a rare swallowing disorder) in 2012, but the study only had 12 participants.

For most people, the temperature you drink your water is down to personal preference and circumstances. Cold water after exercise in summer or hot water to relax in winter won’t make any difference to your overall health.

What source or sources of evidence are used in this snippet?
  • The snippet provides two pieces of evidence.
  • Both are from published research.
    • The first is numerical data.
    • (The second is probably also numerical data but not expressed that way because the sample size is so small.)

What would make this evidence not true?

  • If the writer was making up the studies or misreported the conclusions.
  • If the authors of the research fabricated their data or messed up their collection process in some way.
  • To name a few conditions!

How about this snippet?

Going to work knowing that at any moment you may become the unwilling star of a viral video can exact a considerable toll on the wellbeing of flight attendants.

I speak daily with flight attendants in Australia and abroad as part of my PhD research. From these discussions, I’ve heard from attendants who worry often about discovering videos of themselves featuring unkind comments about their appearance, age or employer.

One flight attendant, Kate*, described the disconcerting feeling of someone aiming a smartphone camera at her while she was simply trying to do her job, saying: "You don’t know why they’re filming or what they’ll do with it."

Marie spoke of being featured in a TikTok video during a safety demonstration, with viewers making fun of her appearance.

Charlotte, after refusing to serve more alcohol to an intoxicated passenger, had a camera thrust in her face, accompanied by threats to her job.

Mark told of how uncomfortable he felt having to ask a passenger to stop taking photos of the crew during service.

These personal accounts illustrate the distress flight attendants can experience when being filmed or photographed without their knowledge.

What source or sources of evidence are used in this snippet?

The evidence in this snippet consists of the personal experiences of other people, that have been collected and presented by the researcher writing the article.

What would make the evidence not be true?

  • If the researcher made up the quotes.
  • If a majority of the respondents exaggerated or lied.

We could probably do a whole lesson about different sources of evidence. For now, all you really need to know is that there are many possible sources of evidence.

To get a feel for the variety, let's do a Balderdash-style game where you make up evidence for a claim.

Here's an ad for an amusement park. The claim is "Our rides are terrifying (in a fun way)" and the evidence is a fake observation.

What other types of evidence could support the claim?

Ad showing split image of a man with one side in a jungle with a snake draped over shoulder and sitting on a roller coaster on the other side
Using dot points: Restate the claim and describe four different sources of evidence. (Personal experience. Observational. Survey & questionnaire. Expert opinion.)

If the claim is "Our rides are terrifying (in a fun way)" then it's worth noting:

  • This is a valuational claim, so we want to match the criteria for terrifying and fun.
  • This is also a specific claim about specific rides; it's not about scary rides in general.

Different sources of evidence could be:

  • Personal experience: Someone who's been on the ride describing or telling the story of how terrifying but fun the rides were.
  • Observation: The ad already provides 'fake' observational evidence with the split screen image of someone screaming (while holding a snake/on a ride). 'Real' observational evidence might be live video of people screaming and then laughing while on the rides.
  • Surveys & questionnaires: "99% of all riders rated our rides BOTH terrifying and fun!"
  • Expert opinion: A quote from a famous ride designer saying that Playland rides are admirably terrifying.

To recap

  • Evidence is material that supports the claim and reason—it's whatever helps make the core argument believable or compelling.
  • Just because something is presented as evidence doesn't necessarily mean that it is true or reliable.
  • There are many different sources of evidence, and some are more reliable than others.