APPENDIX A: LOGICAL FALLACIES

Here we examine some different forms of bad reasoning under the headings: fallacies of relevance, all of which depend on premises not relevant to the conclusion; fallacies of ambiguity, all of which depend on the ways in which many words and expressions can have multiple and often incompatible meanings; and fallacies of presumption, which depend on unacknowledged, unjustified extra assumptions.

Fallacies of Relevance

As we turn to the fallacies of relevance, it is good to remember these fallacies depend on the use of information that may seem relevant to establishing the conclusion but isn’t really relevant after all. They often play on our emotional responses to certain situations and topics and they can be quite effective as means of persuading us. They work so well in getting us to buy into their conclusions in part because of the nature of the human mind – even though we are capable of thinking about things coolly and logically, we often jump to conclusions on emotional grounds and then enlist our cognitive abilities merely to rationalize decisions and conclusions we have already made. Philosophers would encourage us to resist such impulses and to stop and think before jumping to conclusions. This can of course be quite challenging just because of the way in which our brains are wired – the neural pathway between sensory input to motor and cognitive output is shorter in its trip through those parts of the brain that process emotions than it is through our higher cognitive powers. But still, whoever said leading an examined life was the easiest thing to do?

Appeal to authority

My friend who is a scientist insists that global warming is not cause for alarm, and for me that is a good enough reason to accept her conclusion.

This fallacy is also known as “appeal to inappropriate authority.” Appealing to authority is a commonly used way of trying to convince people. But why do we find authorities believable in the first place? Because they are authorities? In this case we may wonder why they are considered authorities at all. On the other hand if they have something to back up their claims, why don’t we just see for ourselves whether they are right or not?

Ad hominem

There is no need to take that animal rights activist seriously. After all, she also benefits from the use of animals – notice her leather shoes and fur mittens.

The name of this fallacy is a Latin expression meaning “against the person.” It is also known as the “abusive fallacy,” or “personal attack.” This very popular fallacy focuses on the personal inconsistency of the person giving the argument in an attempt to discredit their argument. People who use this strategy don’t respond directly to their opponent’s argument but bring up external reasons not to believe anything he or she says. This is clearly wrong since it is the argument that someone gives and its validity and soundness that should be our concern not the person from whose mouth that argument happens to be coming.

Popular appeal (bandwagon fallacy)

The Romans were justified in slaughtering thousands of slaves. After all it was a part of their culture and not many people objected.

This fallacy involves appealing to what most people or the majority of people think as a way of determining what is really true or really right. But as pre-civil rights segregation laws show – what the majority wants or believes can very easily be wrong. The fallacy known as the “appeal to tradition” is similar in that it claims that tradition, the way people have been doing things for a long time, is a good enough basis for us to believe or act as they did. This, of course overlooks the possibility that they were wrong or had no good reason to believe or act as they did.

Appeal to force

The reason that we are right is because we have the military might to get rid of any government that disagrees.

However effective force or threats of force may be in getting people to do what we want, we may wonder whether this approach really is attempting to convince anyone of anything. Even though threats may get people to say that they agree with you, this shows nothing about whether the conclusion is true or whether they really believe what you are saying.

Appeal to consequences

If astronomers are correct, the earth orbits a relatively insignificant star in a remote corner of one galaxy among billions. But this conclusion violates our sense of the significance of our own lives and so it must be false.

This fallacy involves rejecting some particular viewpoint, theory or idea based on the consequences to which it leads. These consequences are often emotionally loaded, the kinds of things that we may not want to believe. However, it is often simply irrelevant whether we like or want to believe something: the truth may in fact be indifferent to what is pleasing to us. The way to tell what the truth of the matter is, is to examine the evidence rather than reject a theory out of hand because it has unappealing consequences.

The naturalistic fallacy

Women alone can have babies. So the responsibility of raising and taking care of them is entirely theirs.

Next, we have the naturalistic fallacy. We often appeal to nature as if natural things, practices, etc. were automatically good. This is perhaps understandable in a world filled with various artificial substances of dubious safety. But we should be careful of making such appeals since they involve a leap of logic. The problem with the naturalistic fallacy is actually quite a general problem – the attempt to conclude something about what should or ought to be the case from what simply is the case. In this example, the facts of how human reproduction work entail nothing about who should play what role in raising children. That is a matter of social relations that, us philosophers hope, should be based on a free and open (and rational) discussion between those involved and not on the “facts of life.”

The genetic fallacy

Newspapers are businesses that make profits from selling papers. So we should distrust what they publish since it is bound to be affected by their desire to make money.

Arguing like this is a more general version of the naturalistic fallacy. We often assume that where something comes from affects its nature in fundamental ways and so we automatically tend to distrust research that is paid for by corporations, we distrust claims made by people who stand to gain from what these claims are about and so on. Although it may seem like wise advice to “follow the money” and keep in mind that those who pay the bills might use their power to determine the content of the conversation, insisting that this must be the case simply does not follow. In the case of the news media, the fact that a large newspaper corporation makes money for its employees doesn’t automatically slant what exactly they are saying in one way or another. This is because one part of their business strategy might also be to maintain high standards of independently verified journalistic integrity. If they are selling their reputation as reliable reporters, and there is an independent way of determining the truth of their claims, there is not necessarily a conflict built into the idea of selling newspapers. Just as in the case of other fallacies of relevance, such as appeal to authority and ad hominem, in this case what matters is not so much who is saying something but what is being said, and we can see for ourselves whether it is reliable or slanted in any way.

Red herring

We shouldn’t worry that much about people dying of horrible diseases in Africa. After all we have problems of our own to deal with.

The name of this fallacy comes from the British method of fox hunting. First a captive fox is released and then a pack of foxhounds follow its scent trail, followed in turn by the hunters. In order to make it a little more difficult for the hounds to follow the fox, a piece of smoked herring (a smelly fish that typically is red in color) is wiped on the ground across the fox’s path and thrown off to the side somewhere. This serves to distract and confuse the hounds and gives the fox a chance to get away. In an argument whenever you bring up something irrelevant in order to draw attention away from the topic at hand you are relying on the fallacy of red herring. The problem with the reasoning in this example, of course, is that there is no mention made of the possibility that both problems in Africa and problems here can be addressed. Besides mentioning something off the topic in no way undermines whatever claims are made about that topic.

Weak analogy

Galileo was ridiculed because of his views, and these views later proved to be correct.
I too am ridiculed for believing that the Pope is a reptilian alien in league with the Freemasons. Thus I too will have my day and my views will be accepted.

Analogies are comparisons between different things. We reason analogically when we argue that because one object or concept has a certain feature, other objects or concepts that are similar in certain respects will also have that feature. This is an important way in which we make sense of the world. However, it has its drawbacks. If we are not careful we can end up making analogies when they are not really there. This argument is based on a weak analogy because it is just not the case that all views that are ridiculed end up prevailing in the end. Some do, like Galileo’s, but the reason was not inherent in their being ridiculed, but on their being based on good reasoning supported by evidence in the appropriate ways. And by the way, there really are people who believe that the Pope is a reptilian alien, just google it and see.

Fallacies of Ambiguity

The next set of fallacies relies on the fact that many terms have multiple meanings. Switching between meanings without acknowledging that one is doing so is a way of making invalid reasoning look valid. Closer examination reveals arguments that do this to be weaker than at first glance. Here we will consider just a few examples. Many more often appear in debates and you can find out about many more examples by following the links at the end of this chapter.

Equivocation

People in jail are actually free. This is because if you can think whatever you want, then you are free and people jail can certainly think whatever they want.

Equivocation is using multiple meanings of a word as if they were the same. We start out with one meaning of a word like “freedom” and end up with another meaning, in the attempt to fool the person who is listening to us that our reasoning is valid. Since many words have multiple meanings, it is important to watch out for subtle shifts as an argument progresses.

Straw person

The senator who suggested cutting funding for the new Air Force attack drone system really wants to leave us defenseless against our enemies. Thus we should reject such cuts.

This fallacy often appears in the context of a debate in which one person misrepresents his or her opponent’s view in order more easily to knock it down, like a person made of straw. This is a fallacy of ambiguity in that it relies on a superficially similar version of the view that is being attacked rather than the view itself. One can often “win” debates by using this strategy, but such victories are hollow in that they do not really engage with the real issues. If you really want to demonstrate that some view you are attacking is worthy of rejection, it is far better to rely on the “principle of charity” and present your opponent’s view in as favorable a light as possible. If it still fails, then your position may look even better. The drawback, however, is that if you represent your opponent’s views in a more fair and favorable light, your objections to them may themselves not hold up. But that is really only a drawback if you care more about winning debates rather than in figuring things out.

Cherry picking

This study of 12 children clearly shows a link between childhood vaccination and autism. Thus vaccines cause autism.

This one is really no joke – in fact the whole of the current scare about childhood vaccinations and autism was “established” by a single study of twelve children! The fact that the paper was retracted, and its author was barred from medical practice didn’t matter since its influence only grew since the date of its publication. The logical mistake here is that of selectively reading the evidence in favor of your own hypothesis, or “cherry picking” the data to get the juiciest bits while ignoring anything that contradicts it. The other name for this fallacy, “Texas sharpshooter” refers to the related practice of proving your worth as a target shooter by first shooting random holes in the side of a barn, and then afterwards drawing your target around a cluster of holes so that it looks like you are a great shot. Is this done in Texas? Probably not, but whoever named it must have had a low opinion of Texans – no offense intended and if you are from Texas, substitute your state of choice.

Fallacy of misplaced concreteness

I feel so agitated after I watch the news. That is not so surprising though, since the media is trying to scare us all.

How often have you heard someone say something like “it’s the media’s fault?” While this may be a common way of talking about things, it makes a subtle mistake in reasoning. It treats an abstract noun, “the media” which refers to many different organizations, publications, companies and their vast numbers of employees, owners, stockholders, etc., as if it were a concrete noun: the kind of thing that could meaningfully be referred to as being at fault for something. Concrete things, such as individual people can of course be at fault. Some organizations, such as corporations, can be at fault in a legal sense that they are liable for damages if they do something that is illegal. But can “the media” really be at fault for anything? What would this even mean? To be at fault for something, I for example, have to knowingly and willingly do something that is illegal or otherwise wrong. But this requires that I can know things and will things, that is, that I am person with a functioning mind.

When we talk about abstractions like governments, the media, society and so on, were are no longer talking about particular concrete things, however. Instead we are talking about collections of organizations, institutions, and of course all of the many particular people who run them. And such collections are just not the kinds of things that can do anything on their own. This is not to say that individual news agencies, reporters, publishers or whoever, wouldn’t be responsible for knowingly publishing false or misleading information. Of course they would be. It is also not to say that there might not be general trends – clearly governments run by one particular political party tend to do things that governments run by another party would not. It’s just that we have to be careful about talking about these abstractions – the government, the media, society – as if they were real agents making deliberate decisions. To do so would be to commit the fallacy of misplaced concreteness.

Fallacies of Presumption

The third set of fallacies we will consider here are those that make presumptions, often in a hidden way. That is, they rely on hidden and unstated assumptions written, as it were, between the lines. This strategy, however, cannot withstand critical analysis since if we can get the perpetrator of such fallacies to acknowledge these hidden presumptions we can see them for what they are, mere assumptions without warrant.

Mere assertion

Abortion is just wrong, and that is all there is to it.

This is the simplest and most obvious kind of bad reasoning. As the name implies, mere assertion involves simply stating what you want to establish without presenting any evidence whatsoever to support it. It is truly amazing how often people simply assert something that they may think is true without bothering to offer anything to support this assertion.

Begging the question

You should become a Christian. This is because the Bible says that if you are not a Christian you will go to Hell.

This strange sounding name really applies to a very simple technique. Someone who begs the question is guilty of assuming what they are claiming to establish in their argument. In other words they put a disguised version of their conclusion in the premises of their argument. That is, they are not really arguing for what they claim to be arguing for. This is an example of a fallacy that is nevertheless a valid form of reasoning. The problem here is that we cannot just assume that the conclusion is true, as someone who uses this way of argument is in fact doing. Begging the question is not, of course, always so obvious. We can see that this is a case of begging the question when we realize that the only people who will be convinced by this argument are Christians. Why? Simply because nobody else will take evidence from the Bible seriously, and people who consider the Bible as authoritative are already Christians. This example also shows why begging the question is also known as “preaching to those already converted.”

Appeal to ignorance

The claim that the death penalty deters crime has not been established with any certainty. Thus it is clear that it does not deter crime.

The fact that something has not yet been proven to be true does not mean that it is false. It is just unknown! Yet this fallacy assumes that if we do not have proof of something then that thing must be false.

False dilemma (black or white fallacy)

Either living organisms are products of blind chance or they were deliberately designed.
But it makes no sense that something as functionally complex as a living organism is the result of blind chance. Hence, they must have been designed.

The argument here rests entirely on an assumption that is not always so easy to see, the assumption that the alternatives stated are the only ones there are. If this were the case, then the argument would stand, but often other alternatives are simply not even mentioned. Hence the dilemma, or forced choice between two alternatives, is here a false one. In the example below, which is often used against the theory of biological evolution, the missing alternative is precisely what Darwin articulated in his book On the Origin of Species, a theory which contains an element of chance but which is not reducible to the blind chance that this argument presumes is the only alternative to deliberate design.

Hasty generalization

All three of my ex-wives always told me what to do. This clearly shows that all women want to control us men all the time.

We may be tempted to conclude a lot from a single case, or a relatively small sample, but this is often merely a way to confirm our prejudices. If we really want to make sweeping generalizations, we’ll have to gather a bit more evidence in less clearly biased ways than this.

Slippery slope

If we legalize physician assisted suicide, then everyone over sixty had better watch their backs. Once doctors get used to helping people with terminal illnesses die comfortably, they’ll find it easier to get rid of older people.

Slippery slope arguments are often used as a way of warning us of the dangers of allowing people to do something that is now forbidden. They say, in effect, if we allow someone to do this, then they’ll have no reason not to do that, which is much worse. The name comes from the metaphor of an icy ski slope: if we are foolish enough to step onto the slope, without skis on of course, we’ll end up uncontrollably sliding down to the bottom. The problem with this argument is that it claims that we must end up where the arguer claims we will, but the argument gives does nothing but assert that.

False cause

Most heroin users smoked marijuana when they were younger. So smoking marijuana must be one of the causes of heroin use.

Us humans are very good at noticing patterns in the world around us. In fact science is based on this ability – we notice regularities and then come up with explanations for them. The most powerful of these explanations involve attributing a causal relationship between events that appear to be related to each other in a regular way. We have to be careful here, however, since we also have the tendency to overdo this. This may seem like a convincing argument until we recognize that the fact that something tends to happen before something else is not nearly enough to establish that the first thing causes the second to happen. For example, the fact that my alarm clock goes off every day shortly before sunrise does not mean that my alarm clock causes the sun to rise. The same goes for drug abuse. The fact that I abused marijuana first and then heroin later does not mean that the first caused the second. It is equally possible that I abuse whatever drugs I abuse for another reason – I have major problems I am trying to escape from.

Circular reasoning

He must be guilty, since he has a guilty look on his face. Furthermore, the look on his face indicates guilt, because he is the one who did it.

This final fallacy in our list is, in a sense, a more complex version of begging the question. Circular reasoning involves bouncing back and forth between two assumptions each of which is supposed to be the basis for the other. To see the circular structure of the reasoning exhibited here it may help to figure out which statement is the premise and which is the conclusion. In this example, at first glance it seems like the conclusion is “He is guilty,” and this seems to be based on the premise that “He has a guilty look on his face.” However, the fact that the look on his face indicates guilt is then supported by the assertion that “He did it.” Clearly we are moving around in a circle – our premise supports and is supported by our conclusion. There is thus no real support for either and the whole structure is unfounded. This fallacy is also known as the “vicious circle” fallacy.

Wishful thinking

The tendency to project our own desires onto reality and fool ourselves into thinking that reality conforms to how we would like it to be.

I just know that the Yankees will win the World Series, they just can’t let me down again!

Further exploration

There are many great websites that list, discuss and explain the many ways we get things wrong in our thinking. Here are a few of my favorites.

Your Fallacy Is is a nicely designed website with more examples of common fallacies.

Your Bias Is is the sister site to Your Fallacy Is and focuses on common cognitive biases.

Logically Fallacious is a site with a huge and comprehensive list of logical fallacies and cognitive biases. A great reference with lots of examples.