UK-Skeptics articles and commentary » Fallacies in reasoning

Confirmation: an error of reasoning.

John Jackson — Sun, 01 Feb 2009 10:06:36 +0000

John Jackson © UK-Skeptics

C onfirmation bias is where we look for reasons, or supporting evidence, that matches our belief or thesis whilst disregarding or placing less weight on disconfirming reasons or evidence against it.

As a hypothetical example, let’s look at someone’s belief that hypnotherapy helps people to stop smoking. People do go to hypnotherapists and subsequently give up smoking and there are many people who will anecdotally state that hypnotherapy worked for them. It seems convincing, but is this proof that hypnotherapy really helps people to give up smoking?

If we only consider positive outcomes for our hypothesis, what we’re doing is introducing biases known as selective attention (seeing only what we want to see) and suppressed evidence (avoiding what we don’t want to see). Of course the problem is that using a biased data sample will most likely result in a false conclusion.

Statistics need context to be meaningful. Positive outcomes need to be compared to negative outcomes to give a success rate, and in turn, that success rate needs to be compared to something else to provide context. That could be a competing hypothesis or compared to doing nothing (as a control comparison).

Many problems can be analysed using a simple table like this one:

	(A) Gave up smoking	(B) Failed to give up smoking
(1) Used hypnotherapy	30	70
(2) Did not use hypnotherapy	45	105

Here we’re counting the number of people who used hypnotherapy and gave up smoking but also the number who used hypnotherapy and failed to give up smoking. Then we compare that result to a group of people who did not use hypnotherapy.

Even when faced with data in this form, people who are asked, “does hypnotherapy help people to give up smoking?” will look at the A1 Square and conclude that it does. This happens even with hypotheses we have no interest in because we have a natural tendency to look for confirmatory evidence. Seeking out and being influenced by confirmatory evidence is a human predisposition.

When comparing different sample sizes, we can find the percentage of success to failure in both instances and then compare the results. This can be done in the following way:

Used hypnotherapy :	A1 ————- [A1+B1]	30 ———— [30+70]	= 0.3 (30%)
Did not use hypnotherapy :	A2 ————- [A2+B2]	45 ————- [45+105]	= 0.3 (30%)

As can be seen from the figures, 30% of people who go to a hypnotherapist manage to give up smoking; however, when we give that figure context by comparing it to those who did not go to a hypnotherapist, we find that they too were successful 30% of the time. There is no difference between the two groups; the net benefit from using hypnotherapy is zero.

This example is hypothetical but the model is what is important. Whether looking at psychic “hits”, alternative remedies, whether couples are more likely to get pregnant once they give up on the idea, or that bad things happen in threes, looking only at confirmatory evidence will lead to false conclusions. It’s not unless disconfirming evidence is considered and the hypothesis under consideration is compared to something else can we state whether it is true or not.

Conclusion.

Seeking out and being influenced by confirmatory evidence is something we do naturally. This leads to what I call the “A1 effect”: where people can be influenced, often quite strongly, by information that they already believe is true or would like to be true (information that sits in square A1 in the table).

This is one reason why anecdotal evidence can be so influential. A person who is considering using hypnotherapy to give up smoking, for example, may find a lot of evidence against the method, but if even one single person says, “I tried it and it worked for me” then that can be evidence enough: the A1 effect.

We’re all prone to confirmation bias. Understanding the fact however, can help us reach conclusions that are true by analysing issues properly and not simply seeing what we want to see.

Entitled to an opinion.

John Jackson — Mon, 19 Jan 2009 17:42:57 +0000

John Jackson © UK-Skeptics

“I’m entitled to my opinion”, “you’re entitled to your opinion”. Both of these expressions come up frequently in debates but what do people mean by them and are they of any relevance in a debate?

I’m entitled to my opinion

Tom:	I believe X works.
Jerry:	There’s no evidence to support the fact the X works.
Tom:	Well I believe that X works.
Jerry:	X has been tested in scientific trials and was not found to work.
Tom:	I’m entitled to my opinion.

Anyone who is not impressed by Tom’s argument has a good right not to be; it is entirely vacuous. Nevertheless, this argument is put forward frequently in debates as if it has some merit.

Entitlement.

What do people mean when they claim to have an entitlement to an opinion? Well, the term ‘entitled’ is equivocal so we need to look at what is meant by the different meanings.

Legal.

In the UK we have a right to free speech and free thought. This means that we can hold any opinion that we choose; however, this legal entitlement does not distinguish between valid opinion and invalid opinion. It simply means that we are entitled to an opinion no matter how right or wrong it may be.
Epistemic - (Of, relating to, or involving knowledge).

In an epistemic sense, entitlement is an earned right. It’s where a person has a right to an opinion because it is based on evidence or knowledge for example. In other words, there are good reasons for holding such an opinion. Opinions need to be justified and this distinguishes between valid and invalid opinion.

As can be seen, the two meanings of ‘entitled’ are quite different to each other. In fact, they are the opposite of each other. (1) states that we have the right to believe anything, with no regard as to whether it’s true; (2) states that we are only entitled to opinions that we can justify, which means having good reasons for holding them.

Its use as an argumentative tactic.

If we look at Tom’s argument, he’s using it in sense (1) – he does have a right to an opinion in this sense; however, he’s implying that his right to an opinion somehow justifies his claim – as in sense (2).

Claiming a right to an opinion in sense (1) adds absolutely nothing to the argument. It is a complete irrelevance that does nothing to resolve the disagreement. Tom may as well have pointed out that he disagrees with Jerry because Ostriches can’t fly! Changing the subject of the argument to whether one is entitled to an opinion merely introduces an irrelevance: the ‘red herring’ fallacy.

If Tom was claiming that he’s entitled to an opinion because he has good reasons for holding it, as in sense (2), then his claim carries more weight. Of course Jerry may also feel justified in claiming an entitlement to his opinion too. If their views differ, then one (possibly both) of them is wrong. If two people claim to be entitled to their opinion (2), how can the argument be resolved? By examining both of their arguments and finding out which has the best reasons to support their conclusion. In other words, by resolving the original argument!

You’re entitled to your opinion

Tom:	Homeopathy works.
Jerry:	No, quality clinical trials have shown that it’s no better than placebo.
Tom:	I know many people for whom it’s worked; and it’s worked for me too.
Jerry:	There are many reasons why something might appear to work. There are no ingredients in homeopathic remedies so they can’t work!
Tom:	Well, you’re entitled to your opinion.

Again, Tom is using the fact that a person is entitled to an opinion as an argumentative tactic but this time in completely the opposite manner. This usage is a rather condescending way of someone telling another person that they don’t agree with them as it includes the assumption that the person saying it is right (perhaps without having even stated their side of the argument) and they know the other person is wrong.

It is nothing more than a statement of presumption and is the Bare Faced Assertion fallacy (I’m right, you’re wrong – because I say so) therefore it is also a complete irrelevance in a debate.

Conclusion.

“Entitled to an opinion” is often used in debates as a defence of a belief or stance on a subject. Whether it’s used to end a debate (1), to add weight to a person’s position (2) or to reject an opponent’s argument, it is equally useless as a debating tactic.

Debates can only be resolved by presenting sound arguments with supporting evidence. Stating one’s rights and entitlements adds nothing to the debating process. Having a right to an opinion does not make that opinion right – or wrong.

Are you skeptical of skepticism?

John Jackson — Tue, 30 Dec 2008 17:20:29 +0000

An examination of the question: can skeptics be skeptical of skepticism?

“There’s no such thing as truth.”

What is wrong with this statement? Well, it’s a statement that is presented as being factual (true) and yet it’s claiming that there is no such thing as truth. The statement refutes itself. Claims or statements like this one create what is known as a self-refuting paradox: the claim could only be true if it were false!

The frequently asked question “are you skeptical of skepticism?” also attempts to create or illustrate the same sort of paradox. If a person is not skeptical of skepticism then they are not being skeptical; thus any claim to being a skeptic must be false. i.e. they are being as dogmatic in their acceptance of skepticism as any ‘believer’ who accepts their particular belief without question. And if they are skeptical of skepticism, then what good reason do they have for advocating something they are skeptical of? If they’re skeptical of the paranormal and skeptical of skepticism, what’s the difference?

At first glance it looks like a very clever question that reveals a fatal inconsistency with skepticism. So how can skeptics tackle this awkward question?

A definition of terms

In order for skeptics to deal with the question “are you skeptical of skepticism?” firstly we need to look at the definitions of the terms used:

Skeptical

Skeptical means doubtful. The Cambridge online dictionary defines skeptical as “doubting that something is true or useful”. For example: “The minister claimed that raising fuel tax would help combat global warming; but the audience were skeptical”.
Skepticism

The common usage of skepticism also means to be doubtful. For example: “The government’s claim to have reduced poverty was met with skepticism”.

However, scientific skepticism, as used by skeptics, does not simply mean to be doubtful. In fact, skepticism is actually a methodology, not a single concept. It is an approach to claims and knowledge that includes many components (see: What is Skepticism?).

Whenever a word has more than one meaning, there’s always the possibility of making a fallacy of equivocation and that is what is happening with the question “are you skeptical of skepticism?” When people use this question they intend it to mean “are you doubtful of your system of doubt?” but when it’s applied to scientific skepticism, what they’re actually asking is “are you doubtful of your methodology?” – in other words, do you or can you question your methods of inquiry?

The intended use of the question is meant to create the paradoxical situation described above but the actual question (as it pertains to scientific skepticism that skeptics advocate) creates no such problem.

The methods of inquiry that constitute skepticism should be subject to doubt and inquiry in the same way that other things are investigated in this manner and the fact that methodologies are open to scrutiny in this way just adds to the strength of skepticism as a tool for acquiring knowledge. Indeed, this is why skepticism has changed from early skepticism where knowledge was thought to be impossible (which is self-refuting!) to modern scientific skepticism that is used as a tool to acquire knowledge. If skepticism wasn’t open to doubt or scrutiny, it would never change.

Conclusion

The question “are you skeptical of skepticism?” is meant to show that skepticism leads to skeptics holding a paradoxical position; however, as has been explained, this seeming paradox is only created by making a fallacy of equivocation by those who don’t know what modern, scientific skepticism actually is.

Skepticism is not the same as merely being skeptical; and not only can skeptics be skeptical of skepticism – they should be.

Appeal to the open mind

John Jackson — Mon, 15 Dec 2008 04:26:50 +0000

Open Mind: A mind open to new ideas, lacking in prejudice, not dogmatic.

It is very common for people who are putting forward a claim to say something like, “you must consider this with an open mind“, or if their claim is rejected they will say something like, “well of course you don’t believe it, you’re closed-minded“.

There are many ways that this ‘appeal to open mindedness’ manifests itself, so let’s have a look at why it is not usually a valid argument:

What is an open-minded person?

An open-minded person is someone who is willing to consider ideas, opinions and arguments purely on their merit. If an idea can be shown to be correct then an open-minded person will alter, or add to, their world-view with this new-found knowledge. If the new idea does not stand up to scrutiny however, it will be rejected.

Having an open-mind does not mean embracing all kinds of weird ideas and uncritically accepting them no matter how bizarre or unsupported by evidence they are. The actual word used to describe a person who will believe in absolutely anything is: credulous.

Why do skeptics often get accused of not having open-minds?

The accusers don’t understand what open-mindedness is.

They confuse open-mindedness with being credulous. They simply don’t understand the difference between the two. If others do not ‘open-mindedly’ share their beliefs or accept their argument as valid, they accuse them of being ‘closed-minded’. This is simply a fallacious Ad Hominem argument.
Those accusers don’t realise what skepticism is.

Skeptics have to be open-minded. They test and examine claims in a scientific, objective way. To do this they have to be open-minded; this is the reason that skeptics are prepared to consider claims that may seem completely ridiculous to most people. Skepticism is not about rejecting ideas: it’s about testing them for validity.
Those accusers don’t realise that open-minded people can reject claims.

Being open-minded about something is a willingness to consider that it may be true: it also means considering the possibility that it may be false. A truly open-minded person’s mind is open to both possibilities. Disagreeing with a person’s position or argument after considering it does not make one closed-minded.

Misuse of the term “open-minded”.

It is the misuse of the term open-minded that the credulous hide behind. They use it as a shield against the use of critical thinking and logical analysis of their ideas, claims, and often bizarre beliefs.

The “I’m open-minded” claim is used to counter the lack of evidence, or the quality of evidence supporting a claim.

The appeal to open-mindedness is really an appeal to relinquish one’s rational integrity. It does not matter how or why something may appear to be true, that there is no credible evidence to support it, or even that it is demonstrably false; it should simply be accepted with an ‘open-mind’. In other words, with non-thinking credulity.

Conclusion.

Open-mindedness is considered a virtue, and true open-mindedness is.

The claim to be open-minded is frequently used by people who wish to sound virtuous, and simultaneously make their opponent sound intolerant, while defending or promoting their ideas and beliefs.

This appeal to be ‘open-minded’ when considering claims that are unsupported by evidence or which are completely bizarre is a fallacious one. Its message is simply: be credulous.

Argumentum ad Derren Browniam

John Jackson — Fri, 24 Oct 2008 15:12:28 +0000

Errors in skeptical debates: Argumentum ad Derren Browniam.

OK, this is not a serious attempt to introduce a newly named logical fallacy! However, I would like to address the usage of the argument whereby people, and often skeptics, try to convince others that what psychics do isn’t real because Derren Brown can do the same things. I jokingly refer to this as the ‘Argumentum ad Derren Browniam’.

Usually, it is made as a response to someone claiming to be a psychic/medium or to have seen one whom they believe to be genuine. The argument goes something like: “well I don’t believe the medium you saw was genuine; after all, look at what Derren Brown can do – and he’s not psychic“.

There are two main problems with this argument:

The first problem with this argument is that Derren Brown’s ability to replicate what another person does in no way actually disproves it. It does weaken their claim as it shows that it can be replicated by normal means, but it doesn’t disprove it: he may simply be obtaining similar results by a different method.
Secondly, people making this argument make the assumption that Derren Brown is using some advanced psychological trickery and, by inference, that psychics/mediums are doing it the same way (using advanced and complex methods) – this is not the case: there’s nothing advanced or particularly complicated about an interaction where psychic belief and claimed ability are encountered that results in a successful reading. In fact, it’s remarkably simple.

In many instances, people state that Derren achieves his amazing psychological manipulations using things like subliminal messages (which don’t really work) or NLP (which is mostly bollocks). All this succeeds in doing is rejecting one form of nonsense (the psychic claim) for another (the bogus psychological explanations Derren gives).

Derren Brown is a magician; a mentalist. In order for mentalism (which really mimics claims of ESP) to work well it has to appear to be something mysterious. Many mentalist feats are performed – such as predicting a 3-digit number someone will choose by (apparently) writing it down first – and the trick leaves people cold because they know that it’s a trick; the problem being that the mentalist achieves his feat without a plausible mechanism or explanation as to how it’s done (unless he’s actually claiming to be psychic; but that’s another kettle of fish). What Derren does is create a plausible mechanism for doing his mentalism. He’s created a persona whereby he can psychologically manipulate people to choose whatever number/word/etc. he chooses to ‘implant’ in a person’s head. The trick is exactly the same as standard mentalism but he’s embellishing it.

It’s the embellishment of standard mentalist tricks that’s the reason that Derren Brown is so good at what he does – not some fantastical psychological ability or the use of advanced NLP techniques. This fallacy (that Derren uses advanced psychology etc.) comes up all over the place, but I do see skeptics (or at least people who don’t believe in psychics) using it too.

The psychology and NLP explanation for what Derren Brown can do is an intentionally false one. It’s what makes Derren’s mentalism ‘work’ and what makes him such a fascinating persona but the explanation is all a part of the illusion.

In summary: Derren Brown’s feats neither disprove nor explain psychic claims in any way.