Critical thinking for Students (15 page)

In all that we have done before, we have taken claims that have been made and we have asked the important questions ‘what do they mean?’ and ‘what is their significance?’ In other words, we have taken the claim as a given, as something for us to work with by asking these questions. But there might be times when we need to ask the question ‘how believable is this claim?’

The word ‘incredible’ tends to be used these days to mean ‘really good’, as in ‘this plate of pasta is incredible’. But its original meaning is ‘not to be believed’. This is sometimes unpacked, as in ‘this witness is not a credible one’ or ‘this report is not credible’. In both cases, the author is saying that what’s being claimed is not believable.

We’re going to look at reasons why claims might be either believable or not. We’re going to use
criteria
to do this. The word ‘criterion’ is the singular form; ‘criteria’ is the plural form. Thus we would say ‘here is a criterion we can use’ and ‘here are criteria we can use’. The word ‘criterion’ comes from a Greek one for a ‘means of judging’.

Before we introduce these criteria, let’s just consider when we might want (or need) to use them. If you are faced with a claim made by a scientist that a particular product has health benefits, and a similar claim made in an advert, which is the more believable? If you came up with an answer to this, then you must have been using at least one criterion.

If you answered that the scientist was the more credible, then you’ve done two things. You’ve judged that the scientist is believable because they’re likely to be reporting honestly and accurately; you’ve also judged that the advert is less believable because the company advertising its product has reasons not to report honestly and accurately.

So what sort of criteria might you have been using? Let’s meet them.

This is a useful criterion to explain why people and organisations make the claims that they do. Though we often think of it in negative terms (like ‘she had a motive to kill her husband’), it simply refers to a reason for doing or saying something. Quite simply, someone might have a strong motive to tell the truth (as well as to lie). So with our scientist, they might have a motive to report information accurately because that’s how they perceive their role (and what their organisation would expect them to do). Similarly, the person creating the advert has a motive to use information that shows the product in the best light. The information available might be accurate but there might be a motive to select which is used (and how it is presented).

Within motive, we can find two other criteria.

Here we have a criterion which again can go both ways (and even then can be subdivided). Bias refers to leaning in a particular direction. This could be leaning towards telling the truth or the opposite. It could also be accidental or deliberate. Someone might not realise that there is other information available, and so does not include it in their claims and arguments. On the other hand, someone might deliberately ignore or suppress some information in order to present their claims and arguments in a particular way. (We’re back to a term we’ve used before – ‘cherry-picking’ – a term which emphasises how only the good bits, the cherries, are picked.)

Here we have another criterion which can go both ways. By ‘vested interest’ we mean that someone or an organisation has a preference for things to go one way rather than another. But, of course, this could result in the truth being told as well as its being distorted. There might be a benefit in information being presented as accurately as possible, as well as one in its being presented inaccurately. Someone who is accused of a crime they didn’t commit has a big vested interest in giving the information that would show that they are innocent. Similarly, someone who is accused of committing a crime they did commit has a big vested interest in not telling the truth. (Unless you happen to be George Washington who, having axed his father’s favourite cherry-tree,
owned up to this act, explaining that ‘I cannot tell a lie’. Fortunately his father was thrilled with his truth-telling son.)

The (now infamous) case of Dr Andrew Wakefield’s ‘evidence’ showing a link between the vaccine against measles, mumps, and rubella (MMR) and autism (and chronic bowel disease) is a good demonstration of how vested interest was seen as weakening the claims made. Dr Wakefield was shown to have received funds from lawyers acting for parents trying to show a causal connection between MMR and autism.

This is a criterion which is seen as a very strong one. If someone is an expert, we tend to regard their claims as being more credible than someone who isn’t. For example, should we pay much attention to the fact that in an October 2009 survey, 62 per cent of the readers of the
Daily Express
didn’t believe that global warming was caused by human activity? These people who thought this were presumably not experts, so we can probably discount them (unless you want to resort to an appeal to popularity). We can contrast our
Daily Express
readers with a report from the Scripps Institution of Oceanography which ‘with more than a century of exploration and discovery in global sciences … is the world’s pre-eminent centre for ocean and earth research, teaching, and public education’. Dr Tim Barnett and his team from this organisation examined literally millions of pieces of data and concluded that there is now no further doubt that global warming has been caused by human activity.

When we looked at the appeal to expertise, we made the point that an appeal will be stronger if the expert has expertise in the appropriate area. Thus, in this example, Dr Barnett’s evidence makes the claim about human activity being the cause of global warming a highly credible one. The beliefs of the
Daily Express
readers appear to bring no expertise to the table.

An important example of how expertise is used to support particular arguments is found in the role of expert witnesses in courts. Examples of these are engineers, forensic scientists, handwriting experts, and doctors. But there can be problems with such expert witnesses. For one thing, juries (and judges) might not be able to understand their evidence fully. It might be highly technical. It might be that juries simply see the expert as knowing best, so their testimony becomes one of the main deciding factors in reaching their verdict. Another problem is that experts might get things wrong! This is especially the case when they move from one area of expertise
to another, without any real challenge. A good example was from the evidence (now discredited) by Professor Roy Meadow in an infamous cot death case (infamous because of the miscarriage of justice). Professor Meadow was there to give medical evidence, in his expert role as a paediatrician, but added statistical calculation into it as well. His expertise in statistics, however, was inadequate, resulting in him arguing that the probability of there being two cot deaths in an affluent family was 1 in 73 million, when the real figure is 1 in 77.

So the criterion of expertise in judging credibility might well be a strong one, but we still have to take care when assessing it.

But, of course, expertise needs to sit alongside the other criteria. Someone with expertise might well still be biased. So expertise could still be trumped by another criterion. The next one is a strong candidate.

This is sometimes referred to only as ‘ability to see’ or ‘ability to observe’. Neither of these versions is adequate in that this criterion is not concerned with just seeing or observing (in that it includes hearing, touching, smell and feeling). We can also use the alternative term ‘sufficient access’, which captures the criterion very well. This is because we are focusing on claims from those who were close enough to something to be able to report on what was going on.

This criterion, of course, has particular relevance when there was something to be able to perceive (or have sufficient access to). For example, after the
Titanic
sank in 1912, the US board of enquiry set up to establish why the ship sank was very keen to have the testimony of survivors. Issues like ‘did the
Titanic
break in half before she sank?’ were put to the witnesses. However, some said the ship did, others that she didn’t. We’re very much into sufficient access here: were they able to see what was going on in the darkness and confusion? (Or did vested interest override sufficient access, given that the strength of the ship was supposed to be a central feature of its construction?)

However, the ability to perceive isn’t relevant just to specific events. It could also be relevant to having sufficient access to information. Thus the credibility of the above Dr Barnett could be enhanced by the fact that he and his team had examined millions of pieces of data. In this way, Dr Barnett’s status becomes even greater than it was before.

Sometimes the ability to observe can produce puzzling evidence. Here’s someone reporting in September 2009 that they had seen a ‘teardrop-shaped object stationary in the sky for two hours’:

Clearly, this can be seen as evidence that one must consider, but what do we do with it? It needs to be assessed in the same way as any other claim. What is its significance? What explanations are there for it? We could use other criteria to help to assess it. For example, what do we know about the person who made the claim? Do they have a motive in making it?

Sometimes the criterion of ability to perceive/sufficient access can be added to that of expertise. This would normally lead to a claim being strengthened. Unfortunately, sometimes this strengthening produces troubling results.

An expert witness in a ‘shaken baby’ case made the claim:

The jury is faced here with an expert adding significance to his evidence in this case by saying that, in all of the cases he’d seen, this was the worst. This made his claim one that was difficult to dismiss. But, of course, though he might have been telling the truth, this did not mean that the injuries were caused by the defendant. However, the jury were impressed by the significance of this claim and brought in a guilty verdict. Unfortunately, this was the wrong verdict. The defendant was subsequently shown to be innocent. But it’s a good (if worrying) example of how one criterion can add force to another.

Here’s another criterion.

A simple way of seeing the significance of this criterion is to look at how the female figure of Justice is often depicted. She has scales to weigh the evidence (which is what we’re looking at here) and a sword to dispense justice when necessary. But, in addition, in some versions, crucially she’s blindfolded. She is dispensing justice
merely according to the balance of the evidence, rather than according to any bias one way or the other.

Neutrality is an important criterion because it’s the counter-weight to any distortion in the evidence due to deliberate bias. It’s no guarantee against bias, of course, because a neutral source could still be accidentally biased.

A good example of neutrality was the BBC’s refusal to carry an appeal by the Disasters Emergency Committee for aid to Gaza in 2009. The Director-General saw this as staying out of the problem of being seen to be taking sides in the dispute between Israel and the Palestinians.

A claim which is made (or supported) by a neutral source can normally be seen as being strengthened by this neutrality.

This can work in opposite directions. Someone or an organisation can have a good reputation and this can serve to strengthen the credibility of claims they make (or support). But a bad reputation would obviously operate to weaken credibility. It might well be that a source with a good reputation is one that has consistently told the truth (or has been seen to do so), and vice versa.

This criterion could go hand in hand with the previous one. A neutral person or organisation could be seen as having a reputation for honesty and, again, vice versa.

When we looked at expertise, we mentioned the Scripps Institution of Oceanography as one which has considerable expertise. But, of course, because of this expertise, it has a massive reputation. And it would be seen as neutral!