Writing Commons: "Logical Fallacies"

Read this article to learn about logical fallacies and how to avoid them. Logical fallacies occur when the chain of reasoning breaks down, which invalidates the conclusion. Try to identify any logical fallacies in your writing by revisiting one of the writing activities for this course or another course

Fallacious Kairos

  • Red Herring: Introducing irrelevant facts or claims to detract from the actual argument. For instance, our invasion of Iraq was predicated, in part, upon the connection between the attacks of 9/11 and Saddam Hussein. The war was described by some as an appropriate response to the terrorist attacks on 9/11, but in reality, the connection between Iraq and Saddam Hussein was a red herring. Hussein was not connected to Al Qaeda, the terrorist network that perpetrated the attacks, or 9/11.
  • Argument from Authority: We already noted that an argument from false authority involves a speaker or writer claiming authority in a particular area without giving evidence of that authority. These claims of authority are obviously connected to ethos, but depending on the argument, may also be connected to kairos. For example, when a political candidate claims that, if action is not taken right now, the nation risks ruin, he or she is identifying him- or herself as an expert on both the nature of the problem as well as the timing.


Fallacious Logos

  • Appeal to Nature: Suggesting a certain behavior or action is normal/right because it is "natural". This is a fallacious argument for two reasons: first, there are multiple, and often competing, ways to define "nature" and "natural". Because there is no one way to define these terms, a writer cannot assume his or her reader thinks of "nature" in the same way he or she does. Second, we cannot assume that "unnatural" is the same as wrong or evil. We (humans) have made lots of amendments to how we live (e.g., wearing clothes, living indoors, farming) with great benefit.
  • Argument from Ignorance: Assuming something is true because it has not been proven false. In a court of law, a defendant is, by law, "innocent until proven guilty". However, judges and jurors must hear testimonies from both sides and receive all facts in order to draw conclusions about the defendant's guilt or innocence. It would be an argument from ignorance for a judge or juror to reach a verdict without hearing all of the necessary information.
  • Straw Man: Intentionally misrepresenting your opponent's position by over-exaggerating or offering a caricature of his or her argument. It would be fallacious to claim to dispute an opponent's argument by creating a superficially similar position and refuting that position (the "straw man") instead of the actual argument. For example, "Feminists want to turn men into slaves". This statement fails to accurately represent feminist motivations – which can be very diverse. Most feminists agree in their goal to ensure women's equality with men. Conceptions of equality can vary among feminists, but characterizing them as men-haters detracts from their true motivations.
  • False Dilemma: Assuming that there are only two options when there are, in fact, more. For example, "We either cut Social Security, or we have a huge deficit". There are many ways to resolve deficit problems, but this statement suggests there is only one.
  • Hasty Generalization: Drawing a broad conclusion based on a small minority. For instance, if you witnessed a car accident between two women drivers, it would be a hasty generalization to conclude that all women are bad drivers.
  • Cum Hoc, Ergo Propter Hoc (With This, Therefore Because of This): Confusing correlation with causation – that is, thinking that because two things happened simultaneously, then one must have caused the other. For example, "There has been an increase in both immigration and unemployment; therefore, immigrants are taking away American jobs". This statement is fallacious because there is no evidence to suggest that immigration and unemployment are related to each other – other than that their rates increased simultaneously.
  • The Slippery Slope: We already noted that the slippery slope argument is often a way to scare readers or listeners into taking (or not taking) a particular action. The slippery slope argument can also function as a false invocation of logic or reason in that it involves a causal statement that lacks evidence. For example, I might argue that if the drinking age were lowered from 21 to 18, vast numbers of college students would start drinking, which in turn would lead to alcohol poisoning, binge drinking, and even death. This conclusion requires evidence to connect the legality of drinking with overindulgence. In other words, it does not follow that college students would drink irresponsibly if given the opportunity to drink legally.


Fallacious Pathos

  • Argument by Dismissal: Rejecting an idea without providing a reason or explanation for its dismissal. For instance, there is a tendency to cry "socialism" when faced with calls for a single-payer system in the ongoing health care debate. Such a dismissal of the single-payer system may include the observations, "This is America!", or, "You are free to live elsewhere if you prefer". While we do live in the United States and people are free to live wherever they want, neither of these observations actually addresses the argument, either for or against the single-payer system. The observer relies on the simple (and fallacious) dismissal of the opposing viewpoint.
  • Argument by Emotive Language: Using emotional words that are not supported by evidence and/or are unconnected to the argument being made. For example, in abortion debates regarding a woman's right to choose, the argument sometimes shifts from a discussion of medical or legal rights to a graphic description of the abortion process or extreme analogies between abortion and genocide. Most would agree that genocide should be prevented and that the destruction of a fetus is a violent procedure, but these observations distract from the conversation about a woman's medical and legal rights.
  • Appeal to Pity: Drawing on irrelevant personal experiences or feelings in order to produce a sympathetic response. For instance, if I were writing about the necessity of universal health care and I included a personal anecdote about falling ill in Canada and being unable to receive free health care, that anecdote would be a fallacious appeal to pity. My personal experience, though interesting, does not illuminate the issue of universal health care.
  • The Slippery Slope: Suggesting that a particular argument or course of action will lead to disastrous consequences without offering evidence. This fallacy usually produces an emotional response. A common example is the assertion that legalizing gay marriage will lead to polygamy, bestiality, and/or pedophilia.


Fallacious Ethos

  • Ad Hominem (Argument to the Person): Attacking the person instead of the argument. For example, "You say I shouldn't drink so much, but you drink every day". The validity of the argument (drink less) can't be based on the behavior of the person making the argument. Instead, the validity of the argument should be evaluated on its own terms – separate from the person making the claim.
  • Argument from Authority: Claiming to be an expert and, on that basis, to be deserving of trust. It's important to remember that there are different kinds and levels of expertise: My weekend cooking class doesn't make me an authority on recipes, though I can honestly say I've studied cooking. So, I might be an authority on some elements of cooking, but not all of cooking. When faced with an argument from authority, it is important to investigate the credentials of the speaker or writer.
  • Appeal to Authority: Using a statement taken out of context as authoritative support. For instance, it would be fallacious to use Malcolm X's declaration "by any means necessary" to justify an oppressed group's violence against police officers. Such an assertion ignores the context, and therefore the complexity, of Malcolm X's statement.
  • Argument from False Authority: Using an expert in a specific field as an expert in all related fields. For instance, if I am writing a paper about heart disease and I quote my chiropractor, Dr. Wallace, then I would be making an appeal to fallacious ethos; despite being a doctor, she is not an authority on heart disease.
  • Appeal to Anonymous Authority: Using appeals to nonspecific groups (e.g., doctors, scientists, researchers, and so on). For example, "Research shows that all women are inferior to men". Or, "Studies indicate that all college students binge drink". Neither of these statements offers a specific credible source, so both claims lack authority.
  • Inflation of Conflict: Using a conflict between two authorities as a reason to dismiss their arguments and knowledge. For instance, it would be fallacious to assert that global climate change does not exist because two scientists disagree about its effects.


Logical Fallacies

By now you know that all arguments operate according to an internal logic. No matter which of the four rhetorical appeals the author uses, her thesis will succeed or fail based on the soundness of her argument. In classical logic, an argument is sound only if all of its premises are true and the argument is valid. And an argument is valid only if its conclusion follows logically from the combination of its premises. For example, Plato's classic syllogism, "All men are mortal; Socrates is a man: therefore, Socrates is mortal" is both valid and sound. Its premises are true, and the conclusion is undeniable given an understanding of the definitions of the terms.

Plato's famous syllogism is an example of a deductive argument; that is, it relies on a process of reasoning from general statements of common knowledge to arrive at a specific and logically consistent conclusion. But most of the arguments you will encounter in college and in life in general take the form of inductive arguments, which move in the opposite direction: from statements of specific instances toward a general conclusion. For instance, if I say that the sun has always risen in the morning, and then conclude that the sun will therefore rise tomorrow, I have formulated an inductive argument. Notice, however, that my conclusion is not necessarily valid given the definitions of the terms. I can be fairly confident that the sun will rise tomorrow in the morning, but I can't be absolutely certain of it. After all, the sun might go supernova overnight.

Of course, given the fact that astronomers suggest that the sun isn't likely to die for at least another four billion years, my inductive argument's lack of absolute certainty shouldn't bother anyone. The point is that because my argument relies on a specific instance known to be true ("the sun has always risen in the morning"), and then moves to a general conclusion ("the sun will therefore rise tomorrow in the morning"), the possibility that I have committed a logical fallacy in the course of my argument is relatively high. That is, somewhere in the chain of reason leading from the premise to the conclusion, I might have unknowingly violated the internal logic my argument needs in order to succeed. The term "logical fallacy" refers to the point – or points – at which that chain of reason snaps, rendering the conclusion invalid.

Not all inductive arguments commit logical fallacies. Indeed, most of the argumentative texts you will encounter in college manage to avoid such faulty reasoning, mainly because successful authors – i.e., those who publish – have learned how to avoid such pitfalls. They know that inductive argumentation is vulnerable to logical fallacies, not only because such arguments start with specific premises and move to general conclusions, but also because their premises so often rely on human values and abstract concepts. Furthermore, poorly constructed inductive arguments often make statements that on the surface appear plausible, but after consideration or further research reveal inconsistencies or outright falsehoods.

For example, let's say that I'm writing an essay attempting to prove that same-sex marriage is wrong and should not be allowed. One of my premises suggests that if same-sex marriage were legal, pretty soon humans would be marrying their dogs. This statement commits a number of logical fallacies, but the most egregious of them is called the slippery slope, which describes a situation in which a generally unacceptable situation (humans marrying dogs) is proposed as the inevitable outcome of a policy change (allowing same-sex marriage). But no evidence exists that such an outcome will in fact obtain. Furthermore, the argument commits a variant of a categorical mistake, because dogs and humans do not belong to the same species; a dog cannot consent to or decline a marriage vow, and marriage legally requires that both parties are willing and able to provide consent. A reader who accepts such arguments at face value simply cannot make an informed decision about the issue at hand. Logical fallacies not only result in bad writing; they also translate to irresponsible citizenship.

Many more logical fallacies exist than can be included in this article. In the sections that follow, you will find explanations of some of the more common examples as they play out within the context of the four rhetorical appeals. Further research in the library and on reliable websites will yield an inexhaustible amount of information on the various logical fallacies (see some example websites below). As you read assigned texts and write your own argumentative essays, you should constantly test the arguments they contain, examining the premises and their links to one another and to the conclusion. Learning to recognize logical fallacies is a skill essential to college-level writing and to critical thinking in general.

Last modified: Thursday, October 24, 2019, 12:22 PM