As a debater, your primary responsibility is to defend your stance on the given motion. Not only does this involve crafting your own arguments, but you also need to be able to rebut the opposing team’s arguments. To accomplish this, try to look for weak points in their case, which often come in the form of logical fallacies. Purdue Online Writing Lab defines logical fallacies as “common errors in reasoning that will undermine the logic of your argument”. There are two main types of fallacies, namely illegitimate arguments and immaterial assertions. Both types are united by the fact that they are rarely supported by evidence. Read on to learn more about the specific logical fallacies, so you can spot them when you hear them and avoid making faulty arguments yourself!

Slippery Slope Fallacy

A slippery slope fallacy posits that if a certain event or phenomenon happens, a cascade of events will follow that will eventually lead to an unlikely outcome. For example, your opponent might say that masks should not be made compulsory during the COVID-19 pandemic for citizens of a particular country because it robs them of their freedoms. If the government can mandate masks, who knows what else they can mandate, and before you know it, the country will have turned into a dictatorship, they might argue. The problem is that mandating masks during a viral pandemic is not the same as dictatorial oppression. This argument ignores the unique circumstances surrounding the debate. In reality, the slope is often not that steep, and the remotely linked extreme consequences described are unlikely to materialize.

Bandwagon Fallacy

Also known as argumentum ad populum in Latin, which translates to “appeal to the people”, the bandwagon fallacy attempts to persuade the audience by appealing to their need for social belonging. An argument containing a bandwagon fallacy asserts that a statement or premise is true or correct, and thus that the audience should agree with it, because a group of people or a notable figure thinks so. This technique is common in advertising, when a product is heralded as the people’s choice, or when it is proclaimed to be loved by a famous celebrity. Naturally, consumers with patriotic values in the first instance or who are fans of the aforementioned celebrity in the second instance would be persuaded into purchasing the product. This is a benign example of a bandwagon fallacy, but it could be harmful when the widely held belief is misguided.

Circular Argument

As the name implies, a circular argument starts and ends at the same place. After stating a premise, the reason given to justify the assertion is merely a repetition of the premise, which is often phrased differently to give the impression of a difference. In effect, the argument is not justified, but might sound like it is to the uncritical ear. For example, your debate opponent might say that “animal testing is necessary because it is indispensable”. This statement simply  repeats what has been said without providing a solid reason to justify animal testing.

Red Herring Fallacy

A red herring fallacy attempts to divert the audience’s attention by broaching an irrelevant topic that is only remotely connected to the subject at hand. The side topic may be easier to discuss, and allows the speaker to avoid addressing/rebutting the argument. For example, in support of child labor, your opponent in a debate may say: “Yes, children may not have the time to go to school to receive an education, but what about the economy?” The speaker effectively agrees with concerns regarding children’s right to an education, and has no rebuttals against it, so he/she shifts the audience’s attention to the economic benefits of child labor.

Post Hoc Ergo Propter Hoc

This fallacy draws a false causal relationship between two events. Specifically, it asserts that if an event occurs after another, then the preceding event must have caused the following event. In reality, there may not be a causal relationship, or even a correlation to begin with. Post hoc ergo propter hoc is common in superstitions. For example, if someone sees a black cat and then proceeds to trip on the sidewalk, fall and hurt himself/herself, he/she may conclude that the black cat caused him/her to experience bad luck. In actuality, a lot of things, such as an untied shoe or haste, could have led to the fall.

Hasty Generalization

A hasty generalization is a conclusion that is drawn too quickly without sufficient or impartial proof, rendering its validity questionable. Stereotypes are a common example of a hasty generalization. For example, in a debate about accepting asylum seekers, your opponent might say that we should not allow refugees in because they are criminals, as exemplified by a few terrorist attacks orchestrated by foreigners. However, this argument is incomplete at best and racist at worst. It fails to account for the full picture, which might show that citizens of the country are just as likely to be criminals and that there may actually be more criminal incidents involving locals than refugees.

Moral Equivalence

This fallacy attempts to draw inaccurate parallels between a minor mistake with a major transgression, so as to make the former seem totally unacceptable. For example, in debating about increasing tax rates for the rich, your opponent may argue that taxation is as immoral as theft because it forcefully takes money away from people. In reality, taxation is hardly equivalent to theft, because taxpayer money may be redistributed to the poor in the form of welfare services, or used to build new infrastructure that benefits all of a country’s residents, whereas stolen money would be used for personal gains by malevolent individuals.

False Dilemma (Either/Or)

When a speaker creates a false dilemma, he/she is attempting to portray a given situation as a black-or-white ultimatum where the failure to take a particular course of action will lead to a devastating outcome. In reality, said devastating outcome is unlikely to occur. A false dilemma simply creates a sense of urgency that threatens an individual into taking action. For example, in a debate about taxing sugary drinks, your opponent might say “we can either stop imposing taxes on soft drinks or their producers can go bankrupt”. This statement falsely assumes that soda companies will perish due to sugar taxes, but that is not the inevitable outcome. They might find ways to adapt by launching healthier alternatives, such as naturally flavored unsweetened seltzer water. Without critical interpretation, the false dilemma may sway some people into wrongfully agreeing with the statement.

Sunk Costs Fallacy

Sunk costs refer to expenses incurred in the past that are not recoverable. When a speaker uses a sunk cost fallacy, they are trying to appeal to the human desire to complete something and not let any previous effort go to waste, even though continuing on the current path may be futile or counterintuitive. For example, to support his/her pro stance on building the wall along the US’ southern border, your debate opponent might say that because the government has already invested a lot of time and money in the endeavor, they should finish building the wall. However, instead of spending on the wall, the money could instead be used on other efforts, such as ultracold freezers for rural hospitals to facilitate the equitable rollout of the COVID-19 vaccine.

Strawman Argument

A person is said to use the strawman argument when he/she attacks a position that his/her opponent does not really hold. The position may be an oversimplified version of the opponent’s actual stance, or a related one on the side. Thus, rebuttals do not directly address the opponent’s position. For example, you might state that current methods of meat production contributes to climate change, and that more sustainable practices should be created. Your opponent might rebut it by saying that you are blaming farmers who are just trying to make a living for the earth’s demise, and threatening their livelihoods by changing the status quo. This is not a fair assertion as you are not blaming farmers, but rather the methods that they are using, which could be a result of large corporations with deep pockets. Farmers could also benefit from the more sustainable practices.

Those are ten of the most common logical fallacies used in debate! The next time you are participating in a debate, you can identify such flawed arguments in your opponent’s speech and rebut effectively. Also, you can avoid making these mistakes yourself, so you can craft a robust argument that is difficult to poke holes in and ultimately win the debate.