This article sets out some more common ways in which arguments can go awry. Show
Species of Fallacious ArgumentsThe common fallacies are usefully divided into three categories: Fallacies of Relevance, Fallacies of Unacceptable Premises, and Formal Fallacies. Many of these fallacies have Latin names, perhaps because medieval philosophers were particularly interested in informal logic. You don’t need to know the Latin names: what’s important is being able to recognize the fallacies. Fallacies of RelevanceFallacies of relevance offer reasons to believe a claim or conclusion that, on examination, turn out to not in fact be reasons to do any such thing. 1. The ‘Who are you to talk?’, or ‘You Too’, or Tu Quoque Fallacy
Responses like that probably sound familiar. But the doctor’s failure to look after her own health is irrelevant to the argument, resting on a concern for the patient’s health, that the patient should quit smoking. 2. The Red Herring Fallacy.
Plans to eliminate or reduce pesticides probably don’t entail stopping the production of common vegetables: the suggestion that they do is an irrelevant red herring. 3. The Strawman Fallacy.
Roger claims that Margaret is proposing measures that would eliminate cars. Margaret has not said anything equivalent to that. It’s a strawman. A positive message from the Strawman: the importance of being charitable. Showing that a strawman version of a position we oppose may win a debate, but it is unlikely to move us toward the truth. If we can show that even the strongest version of a position we oppose is flawed, we may make progress. So good logical and critical thinking leads to the principle of charity: When representing an argument that you do not agree with and are attempting to evaluate, it is important to represent that argument in a way that is reasonably faithful to the argument as it is made by the originators, and as strong as possible.
But if Myer has given arguments in favour of his view, we should evaluate them like any other argument – are they valid? strong? sound? cogent? (we’ll explain these terms in the course) – rather than writing them off because of facts about him. Sometimes, however, an arguer’s position may be a reason to examine their arguments more carefully than we might otherwise. The following does not appear fallacious:
Newsreaders look well informed, but they are essentially presenters. They are well known because they’re on the news: not because they know about investments. If we rely upon a newsreader’s endorsement to settle which investment fund we should trust, we would be accepting a claim without adequate evidence. That would be a fallacious appeal to authority. Appeals to authority also conflict with the basic tenet of good logical and critical thinking which calls upon us to take responsibility for evaluating the grounds for our beliefs. Adopting a belief merely because someone else simply told us it was true is a way of avoiding good logical and critical thinking. Sometimes, however, good logical and critical thinking will itself lead us to rely on genuine authorities. If I can’t assess the investment option for myself, I might reason that I should trust the advice of a genuine investment advisor. That’s not avoiding logical and critical thinking: it’s reasoning about a matter related indirectly to the question I’m trying to settle. When I consider whether I should rely on a genuine authority, I should consider the following questions:
Only if the answer to all four of these questions is “yes” should we accept a claim because an authority endorses it, and even then, we should only do so if we are not in a position to evaluate the evidence for the claim ourselves. 6. The Fallacy of Composition.
Sadly, for Tim, a long-suffering Blues Fan, the conclusion of this argument was false even though the premises were true. And, showing that famous philosophers are not immune:
7. The Fallacy of Division.
Tim would have to be taller than 188cm/6ft 2in to be taller than Sharapova: he’s not. 8. Equivocation.
When the two senses of ‘law’ (laws regulating human conduct vs. uniformities of nature) are made explicit, it is apparent that the first premise is irrelevant, hence a fallacious argument. And, showing that famous philosophers are not immune again, we see John Stuart Mill arguing that happiness is desirable:
But ‘desirable’ is used in two different ways in this passage, to mean ‘can be desired’ (just like ‘visible’ means ‘can be seen’) and ‘worthy of being desired’. 9. Appeal to Popularity.
Perhaps the Bible is true, but the fact lots of people believe it to be so is irrelevant to whether it is or not. We should investigate and evaluate their reasons for believing it, rather than taking the mere fact that they believe it as a reason to do so. But … sometimes a consensus among properly informed people may be a fairly good guide to the truth of a claim: see the circumstances in which an appeal to authority might not be fallacious. 10. Appeal to Tradition.
But all of the objections to arguments from majority belief apply here, too.
Note: When we describe someone as ignorant, we often mean it as an insult. Here we use it to describe the situation in which we do not know (are ignorant of) something. In this sense, the smartest of us are ignorant of quite a lot. (We don’t want any equivocation in our use of the term ‘ignorant’).
Both claims assume that the lack of evidence for (or against) a claim is good reason to believe that the claim is false (or true). Ignorance – in the sense of a lack of knowledge – features as part of the proof of the conclusion. But in general, the mere fact that a claim has not yet been proven is not enough reason to think that claim is false. However, are there some non fallacious appeals to ignorance? a) If qualified researchers have used well-designed methods to search for something for a long time, without success, and it’s the kind of thing people ought to be able to find, then the fact that they haven’t found it might constitute some evidence that it doesn’t exist. b) Some practices (e.g. law – see week 6) require us to reject a claim until a certain standard of proof is met: the presumption that defendants are innocent until proven guilty beyond a reasonable doubt for example. 12. Appeals to Emotion – e.g., pity, affection.
That would be an appeal to emotion, in this case love. Note that the persistent child might continue:
That would be a strawman, not contemplated by the father or entailed by his actual view, and attacking that. Being able to spot the common fallacies can be very useful in the home. Remember, there are three species of fallacies. The Fallacies of Relevance sketched so far attempt to introduce premises that are irrelevant to the conclusion. Fallacies of Unacceptable PremisesFallacies of Unacceptable Premises attempt to introduce premises that, while they may be relevant, don’t support the conclusion of the argument. 13. Begging the Question.
The Bible could only be divinely inspired if God existed. So Arthur’s appeal to the Bible to prove the existence of God assumes the very thing he’s trying to prove. 14. False Dilemma or False Dichotomy.
It’s possible that Shakespeare didn’t write all of the plays attributed to him, but that doesn’t mean Bacon did: there are other possibilities. In the Shakespeare/Bacon case the false dilemma was explicit (either Shakespeare wrote all the plays … or Bacon did), but often the dilemma is implicit. If I spend all of the week partying, I won’t have time to study and I’ll fail. If I spend all week studying, I’ll be over-prepared and stressed and I’ll fail. So I’m going to fail either way. I might as well spend the week partying. Here the dilemma is unstated – “The only options are to spend all week studying or to spend all week partying” – and once stated it surely isn’t plausible: the student could spend some of the week studying and some of the week partying? 15. Decision Point Fallacy or the Sorites Paradox.
If an arguer claims that because we cannot identify a precise cut-off or decision point, we cannot distinguish between correct and incorrect uses of the term, they are arguing fallaciously.
But we can tell the difference between people who are bald and not bald, between heaps and non-heaps, and embryos and babies, even if we can’t tell exactly when something stopped being one thing and became the other. 16. The Slippery Slope Fallacy.
Slippery Slope arguments are fallacious if it is possible to stop at one of the steps: couldn’t I get a credit card with a maximum, or exercise a bit of control, or get the local animal protection society to help me feed the dog? 17. Hasty Generalisations.
The claim that smoking carries significant health risks isn’t falsified by a single case and trials drawing population wide conclusions must recruit representative study-populations. 18. Faulty Analogies.
Are visits to after-hours medical clinics with a sick child analogous to visits to a gas station or a restaurant? 19. And … the Fallacy Fallacy!
The conclusion of an argument may be true, even if the argument contains a fallacy. Finding a fallacy just means that the arguer needs to look for other, better reasons in support of their conclusion. Formal FallaciesThe third species of fallacy are Formal Fallacies. Some arguments are fallacious not because of their content – because of what they say – but because of their form or structure. Any argument with these forms or structures will be invalid, no matter what content we put into them. Patrick will talk a little more about the standard forms or structures of arguments in weeks 2 to 4. The most familiar versions have some number of premises, followed by a conclusion, and if they’re valid (Patrick will talk about that in week 3) the truth of the premises guarantees the truth of the conclusion. There are some common argument forms, however, which look quite like the valid versions, but which are not valid. Here we’re just going to identify two formal fallacies that will come up later in the course. 20. Affirming the consequent.Suppose I have a guard dog, Brutus, and I’m confident he will bark if an intruder comes into my house. I might reason like this:
That’s valid: If it’s true that Brutus will bark if there’s an intruder, and if Brutus hasn’t barked, then there can’t be an intruder. If the premises are true, then the conclusion must be true too. But what if I reason like this:
That’s not valid. Why? Well the premises might be true, but the first premise doesn’t say that Brutus will bark if and only if there’s an intruder. The first premise can be true – that is it can be the case that Brutus will bark if there’s an intruder – even if Brutus occasionally barks for other reasons as well. Notice that you can’t respond here “Oh, the burglar might have fed Brutus tranquilized steak. That’s why he hasn’t barked. There is a burglar!” That rejects the first premise (If there’s an intruder, Brutus will bark), and we’re seeing what happens if the premises are true. So here, if the premises are true, the conclusion must follow. 21. Denying the Antecedent.Suppose I hear barking and reason like this:
That’s valid. If the premises are true – if it’s true that if it barks it’s a dog and it barks – then the conclusion must be true too. But what if I reason like this:
That’s not valid. The first premise says that if something barks then it’s a dog (i.e., that only dogs bark), but it doesn’t say that every dog barks. So we can’t be sure that the conclusion of this second argument is true even if the premises are true. It might be true that something doesn’t bark (i.e., the antecedent is false, or denied, as the second premise says), but is a dog. Fallacious Argument FAQSIn traditional philosophy and logic, a non sequitur is classified as a logical fallacy because it involves flawed reasoning. This fallacy occurs when it is readily apparent that there’s no connection between a given premise and the conclusion drawn. Today, the term non sequitur is also used to describe remarks that have no relation to what was previously said and remarks that come out of the blue, indicating that the speaker was not paying attention. When an argument’s premise assumes the truth of the conclusion, as opposed to supporting the argument being made, this indicates a begging the question fallacy. In its interrogative form, that is, when posed as a question, a begging the question fallacy is known as a complex question fallacy. In either form, the error in logical reasoning remains the same. You can identify a common fallacy in an argument by pinpointing any instances of irrelevance and/or flawed logic. There are several types of common fallacy and they are categorised according to how they function and the principles of logic. However, each type of common fallacy has a commonality in that all fallacies involve errors in reasoning. Common fallacies involve errors in reasoning. Studying fallacies teaches you to identify these errors in other people’s arguments and avoid them in your own. Learning how the different types of common fallacies are defined and categorised also means you’re equipped with a convenient way to critique and describe arguments. The purpose of common fallacies is to persuade others that an argument or conclusion is valid, even when it is not supported by sound logic and reasoning. Fallacies are employed by all manner of speakers and writers, from advertisers and television presenters to the friendly neighbour down the street. People may be aware or unaware that they are making a fallacious argument. Amphiboly is a type of informal common fallacy that involves grammatical ambiguity. The fallacy of amphiboly occurs when the grammar of a statement, be it written or spoken, leaves the statement open to multiple interpretations. Amphibolous statements in writing are often the result of poor sentence structure. The best way to argue a point without falling into the trap of common fallacies is to know your subject well and be equipped with plenty of evidence to support each statement or proposition that leads to your conclusion. It’s also helpful to understand common logical fallacies and how they function to ensure you do not unintentionally rely on fallacious arguments. Presenting a well-structured argument is a matter of applying logic and sound reasoning, to do this, you need to avoid fallacies. While the terms logical thinking and critical thinking are often used interchangeably, there are differences between the two. Logical thinking is the process of evaluating truth conditions and the legitimacy of connections between statements by applying formal deductive logic. Critical thinking pays heed to logical thinking processes yet allows for less rigid evaluations while remaining analytical. One of the best ways to develop critical thinking skills is through ongoing education. Although it sounds funny – given that we think constantly – in many ways, we have to be taught how to think critically. Outside formal education, you can develop critical thinking skills by questioning what you read and hear. Don’t accept statements or interpretations at face value, instead, research the topic itself and related topics to learn more and draw your own conclusions. Remember to approach a topic from different viewpoints and angles to gain a well-rounded perspective. A logical argument is one that relies on the principles of classical logic to establish veracity. An excellent example is this classic: If A = B and B = C, then A = C. We can replace these placeholders with any number of options. For instance: Dogs are canines, canines are mammals, therefore all dogs are mammals. Each proposition, or statement, in this example follows a logical order, the hallmark of a logical argument. If we removed the middle proposition (canines are mammals), the argument would be: Dogs are canines, all dogs are mammals. While we might know this is true, the missing proposition means the argument is no longer presented logically. © Tim Dare, University of Auckland Which of the following consequences of the Columbian Exchange most affected American Indians in the 16th century?The spread of disease. Possibly the most dramatic, immediate impact of the Columbian Exchange was the spread of diseases. In places where the local population had no or little resistance, especially the Americas, the effect was horrific. Prior to contact, indigenous populations thrived across North and South America.
Which of the following statements is true about the Mughal and Ottoman empires in the sixteenth century?Which of the following statements is true about both the Mughal and Ottoman empires in the sixteenth century? In both empires the majority of the people were Muslims.
Which of the following represents a significant change in Africa between 1450 CE and 1750 CE?Which of the following represents a significant change in Africa between 1450 C.E. and 1750 C.E.? Most enslaved Africans were transported across the Atlantic instead of the Sahara. Which of the following was a major change in global patterns of religious beliefs and practices in the period 1450-1750 C.E.?
Which of the following best describes the impact on African society of the tree depicted on the map?Which of the following best describes the impact on African society of the trade depicted on the map? Gender and family roles were restructured as the male population in West Africa diminished.
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