Which Common Logical Fallacy Draws A Broad Conclusion Based On Too Little Evidence?

What this handout is about

This handout discusses mutual logical fallacies that you may see in your own writing or the writing of others. The handout provides definitions, examples, and tips on avoiding these fallacies.

Arguments

Most academic writing tasks require yous to brand an statement—that is, to present reasons for a particular claim or interpretation you are putting forward. You may take been told that you need to make your arguments more logical or stronger. And you may have worried that you simply aren't a logical person or wondered what it means for an argument to be strong. Learning to make the best arguments yous can is an ongoing process, only it isn't impossible: "Being logical" is something anyone can do, with practice.

Each argument you make is composed of bounds (this is a term for statements that express your reasons or evidence) that are arranged in the right way to back up your conclusion (the main claim or interpretation yous are offering). You can make your arguments stronger by:

1. using good premises (ones y'all have skilful reason to believe are both true and relevant to the effect at hand),
2. making sure your premises provide skillful support for your conclusion (and not another determination, or no conclusion at all),
3. checking that you have addressed the virtually important or relevant aspects of the issue (that is, that your premises and conclusion focus on what is really important to the issue), and
4. non making claims that are so stiff or sweeping that yous can't really support them.

You also need to be sure that you present all of your ideas in an orderly way that readers can follow. See our handouts on argument and organization for some tips that will amend your arguments.

This handout describes some means in which arguments often fail to exercise the things listed above; these failings are called fallacies. If you're having problem developing your argument, check to see if a fallacy is function of the problem.

It is specially like shooting fish in a barrel to sideslip up and commit a fallacy when you have strong feelings about your topic—if a conclusion seems obvious to you, you're more likely to just assume that it is truthful and to be careless with your evidence. To aid you encounter how people ordinarily make this fault, this handout uses a number of controversial political examples—arguments near subjects like abortion, gun control, the death sentence, gay spousal relationship, euthanasia, and pornography. The purpose of this handout, though, is not to argue for any particular position on any of these issues; rather, information technology is to illustrate weak reasoning, which can happen in pretty much whatsoever kind of argument. Delight be aware that the claims in these examples are just made-up illustrations—they haven't been researched, and y'all shouldn't employ them as evidence in your own writing.

What are fallacies?

Fallacies are defects that weaken arguments. By learning to look for them in your own and others' writing, you can strengthen your power to evaluate the arguments you make, read, and hear. It is of import to realize two things almost fallacies: first, beguiling arguments are very, very mutual and tin exist quite persuasive, at least to the coincidental reader or listener. You can find dozens of examples of fallacious reasoning in newspapers, advertisements, and other sources. Second, it is sometimes hard to evaluate whether an argument is fallacious. An argument might be very weak, somewhat weak, somewhat strong, or very strong. An argument that has several stages or parts might have some potent sections and some weak ones. The goal of this handout, then, is not to teach you how to label arguments as fallacious or fallacy-free, but to help you expect critically at your own arguments and motion them away from the "weak" and toward the "potent" finish of the continuum.

So what practice fallacies wait like?

For each fallacy listed, in that location is a definition or explanation, an example, and a tip on how to avoid committing the fallacy in your own arguments.

Hasty generalization

Definition: Making assumptions well-nigh a whole group or range of cases based on a sample that is inadequate (unremarkably because it is atypical or too pocket-size). Stereotypes about people ("librarians are shy and smart," "wealthy people are snobs," etc.) are a common example of the principle underlying jerky generalization.

Example: "My roommate said her philosophy class was difficult, and the one I'one thousand in is hard, too. All philosophy classes must be hard!" Two people'due south experiences are, in this instance, not enough on which to base a decision.

Tip: Ask yourself what kind of "sample" y'all're using: Are you relying on the opinions or experiences of but a few people, or your own experience in just a few situations? If so, consider whether you need more bear witness, or perchance a less sweeping conclusion. (Notice that in the example, the more small determination "Some philosophy classes are hard for some students" would not exist a hasty generalization.)

Missing the betoken

Definition: The premises of an argument do support a item conclusion—just not the conclusion that the arguer actually draws.

Instance: "The seriousness of a punishment should match the seriousness of the crime. Right now, the punishment for boozer driving may just exist a fine. But drunk driving is a very serious law-breaking that can kill innocent people. So the death penalty should be the penalty for drunk driving." The argument actually supports several conclusions—"The penalty for drunk driving should be very serious," in detail—but information technology doesn't support the claim that the decease punishment, specifically, is warranted.

Tip: Separate your premises from your conclusion. Looking at the bounds, ask yourself what decision an objective person would reach later reading them. Looking at your conclusion, ask yourself what kind of show would be required to back up such a conclusion, and then see if you've actually given that evidence. Missing the point oft occurs when a sweeping or extreme conclusion is being drawn, then be especially careful if you know you're challenge something big.

Mail hoc (besides chosen false cause)

This fallacy gets its proper noun from the Latin phrase "post hoc, ergo propter hoc," which translates every bit "subsequently this, therefore considering of this."

Definition: Assuming that because B comes afterwards A, A caused B. Of grade, sometimes one upshot really does cause another one that comes later on—for example, if I annals for a class, and my name later appears on the curlicue, it's true that the first upshot caused the ane that came afterward. But sometimes 2 events that seem related in time aren't really related equally cause and result. That is, correlation isn't the same matter as causation.

Examples: "President Jones raised taxes, and so the rate of violent crime went up. Jones is responsible for the ascent in crime." The increase in taxes might or might not be one factor in the rising crime rates, just the argument hasn't shown us that one caused the other.

Tip: To avert the post hoc fallacy, the arguer would need to give us some caption of the process past which the tax increase is supposed to accept produced college crime rates. And that'south what you should exercise to avoid committing this fallacy: If you lot say that A causes B, you should have something more to say about how A caused B than simply that A came beginning and B came afterwards.

Slippery slope

Definition: The arguer claims that a sort of chain reaction, usually ending in some dire upshot, will have identify, but there's really not plenty prove for that assumption. The arguer asserts that if we accept even i stride onto the "slippery gradient," we will end upwards sliding all the way to the lesser; he or she assumes we tin can't stop partway down the hill.

Case: "Fauna experimentation reduces our respect for life. If nosotros don't respect life, we are probable to be more than and more tolerant of trigger-happy acts similar war and murder. Before long our club will become a battlefield in which everyone constantly fears for their lives. Information technology will exist the terminate of civilization. To prevent this terrible consequence, we should make animal experimentation illegal right now." Since beast experimentation has been legal for some fourth dimension and civilization has non however ended, it seems peculiarly clear that this concatenation of events won't necessarily have place. Even if we believe that experimenting on animals reduces respect for life, and loss of respect for life makes us more tolerant of violence, that may be the spot on the hillside at which things cease—we may not slide all the style down to the end of culture. And so we have not still been given sufficient reason to take the arguer's conclusion that we must make animal experimentation illegal right now.

Similar post hoc, slippery slope can be a tricky fallacy to identify, since sometimes a chain of events really tin can be predicted to follow from a certain activity. Here'southward an instance that doesn't seem beguiling: "If I fail English 101, I won't exist able to graduate. If I don't graduate, I probably won't be able to become a good job, and I may very well terminate up doing temp work or flipping burgers for the next twelvemonth."

Tip: Check your statement for bondage of consequences, where you lot say "if A, then B, and if B, then C," and so forth. Make sure these chains are reasonable.

Weak analogy

Definition: Many arguments rely on an illustration between two or more objects, ideas, or situations. If the two things that are being compared aren't really alike in the relevant respects, the analogy is a weak i, and the argument that relies on it commits the fallacy of weak analogy.

Case: "Guns are like hammers—they're both tools with metal parts that could be used to kill someone. And yet it would exist ridiculous to restrict the purchase of hammers—so restrictions on purchasing guns are equally ridiculous." While guns and hammers do share certain features, these features (having metallic parts, existence tools, and being potentially useful for violence) are not the ones at stake in deciding whether to restrict guns. Rather, nosotros restrict guns because they tin hands exist used to kill large numbers of people at a distance. This is a feature hammers do not share—it would be hard to kill a crowd with a hammer. Thus, the illustration is weak, and so is the argument based on it.

If you think about it, you can brand an illustration of some kind betwixt almost whatever two things in the world: "My paper is like a mud puddle considering they both get bigger when it rains (I work more when I'm stuck within) and they're both kind of murky." So the mere fact that you can draw an analogy between 2 things doesn't testify much, by itself.

Arguments by illustration are frequently used in discussing abortion—arguers frequently compare fetuses with developed human beings, and and then fence that treatment that would violate the rights of an adult human existence also violates the rights of fetuses. Whether these arguments are good or not depends on the strength of the analogy: exercise adult humans and fetuses share the backdrop that requite adult humans rights? If the property that matters is having a homo genetic code or the potential for a life total of homo experiences, adult humans and fetuses do share that property, and so the argument and the analogy are strong; if the belongings is being self-aware, rational, or able to survive on 1's own, adult humans and fetuses don't share information technology, and the analogy is weak.

Tip: Identify what properties are of import to the claim you lot're making, and see whether the two things you're comparing both share those properties.

Appeal to authorization

Definition: Often we add strength to our arguments past referring to respected sources or authorities and explaining their positions on the bug we're discussing. If, however, we endeavour to get readers to agree with us simply by impressing them with a famous proper noun or by appealing to a supposed authority who actually isn't much of an expert, we commit the fallacy of entreatment to authority.

Example: "Nosotros should abolish the capital punishment. Many respected people, such every bit player Guy Handsome, have publicly stated their opposition to it." While Guy Handsome may exist an authority on matters having to exercise with interim, there's no detail reason why anyone should be moved by his political opinions—he is probably no more of an authority on the expiry penalty than the person writing the newspaper.

Tip: In that location are two like shooting fish in a barrel ways to avoid committing appeal to potency: First, make sure that the authorities you cite are experts on the subject you're discussing. 2d, rather than just maxim "Dr. Authority believes 10, and then we should believe it, too," attempt to explicate the reasoning or evidence that the authority used to go far at his or her opinion. That way, your readers have more to continue than a person's reputation. Information technology likewise helps to choose authorities who are perceived as fairly neutral or reasonable, rather than people who will exist perceived equally biased.

Advertisement populum

Definition: The Latin proper name of this fallacy ways "to the people." There are several versions of the advert populum fallacy, merely in all of them, the arguer takes advantage of the desire near people have to be liked and to fit in with others and uses that want to endeavor to get the audience to accept his or her argument. 1 of the most common versions is the bandwagon fallacy, in which the arguer tries to convince the audience to do or believe something because everyone else (supposedly) does.

Example: "Gay marriages are simply immoral. seventy% of Americans recollect then!" While the stance of almost Americans might be relevant in determining what laws we should have, it certainly doesn't make up one's mind what is moral or immoral: in that location was a time where a substantial number of Americans were in favor of segregation, only their opinion was not evidence that segregation was moral. The arguer is trying to go us to agree with the conclusion past appealing to our desire to fit in with other Americans.

Tip: Make sure that yous aren't recommending that your readers believe your conclusion because everyone else believes information technology, all the cool people believe it, people volition like you better if y'all believe it, so along. Go along in mind that the pop opinion is not e'er the right ane.

Advertisement hominem and tu quoque

Definitions: Like the entreatment to authorisation and advertising populum fallacies, the ad hominem ("against the person") and tu quoque ("you, too!") fallacies focus our attending on people rather than on arguments or prove. In both of these arguments, the conclusion is usually "You shouldn't believe And then-and-So's statement." The reason for not assertive So-and-So is that Then-and-So is either a bad person (ad hominem) or a hypocrite (tu quoque). In an ad hominem statement, the arguer attacks his or her opponent instead of the opponent's argument.

Examples: "Andrea Dworkin has written several books arguing that pornography harms women. But Dworkin is just ugly and bitter, so why should we listen to her?" Dworkin's advent and character, which the arguer has characterized so ungenerously, accept nothing to do with the strength of her argument, so using them equally evidence is beguiling.

In a tu quoque argument, the arguer points out that the opponent has actually washed the affair he or she is arguing against, and so the opponent's argument shouldn't be listened to. Here's an instance: imagine that your parents take explained to you why you shouldn't smoke, and they've given a lot of good reasons—the impairment to your health, the cost, and and so forth. You answer, "I won't accept your argument, considering yous used to smoke when you were my age. You did information technology, too!" The fact that your parents take done the thing they are condemning has no bearing on the premises they put frontward in their argument (smoking harms your health and is very expensive), and so your response is beguiling.

Tip: Exist sure to stay focused on your opponents' reasoning, rather than on their personal character. (The exception to this is, of course, if you are making an argument about someone's character—if your conclusion is "President Jones is an untrustworthy person," premises near her untrustworthy acts are relevant, not fallacious.)

Entreatment to pity

Definition: The appeal to compassion takes place when an arguer tries to get people to accept a conclusion by making them feel distressing for someone.

Examples: "I know the exam is graded based on performance, but you should requite me an A. My cat has been ill, my car broke downwards, and I've had a cold, so it was actually hard for me to written report!" The conclusion here is "Y'all should requite me an A." Only the criteria for getting an A have to do with learning and applying the cloth from the form; the principle the arguer wants us to accept (people who have a hard week deserve A'due south) is clearly unacceptable. The information the arguer has given might experience relevant and might even get the audience to consider the conclusion—just the information isn't logically relevant, and so the statement is beguiling. Hither's another case: "It'due south incorrect to taxation corporations—call back of all the money they give to charity, and of the costs they already pay to run their businesses!"

Tip: Make certain that you lot aren't merely trying to get your audience to agree with you by making them feel sorry for someone.

Appeal to ignorance

Definition: In the appeal to ignorance, the arguer basically says, "Look, there's no conclusive evidence on the effect at hand. Therefore, you should take my determination on this effect."

Case: "People take been trying for centuries to prove that God exists. Only no one has yet been able to prove it. Therefore, God does not exist." Here's an opposing statement that commits the aforementioned fallacy: "People take been trying for years to bear witness that God does not exist. Just no one has still been able to testify it. Therefore, God exists." In each example, the arguer tries to use the lack of evidence equally back up for a positive claim most the truth of a determination. There is one situation in which doing this is non fallacious: if qualified researchers have used well-thought-out methods to search for something for a long time, they oasis't found it, and it's the kind of thing people ought to be able to find, and so the fact that they haven't found it constitutes some bear witness that it doesn't exist.

Tip: Look closely at arguments where you point out a lack of evidence and and so draw a conclusion from that lack of evidence.

Straw man

Definition: One way of making our own arguments stronger is to conceptualize and answer in advance to the arguments that an opponent might make. In the straw man fallacy, the arguer sets up a weak version of the opponent's position and tries to score points past knocking it down. But just equally beingness able to knock downwards a straw man (like a scarecrow) isn't very impressive, defeating a watered-downwardly version of your opponent's argument isn't very impressive either.

Case: "Feminists desire to ban all pornography and punish anybody who looks at it! But such harsh measures are surely inappropriate, so the feminists are wrong: porn and its fans should be left in peace." The feminist statement is made weak past being overstated. In fact, most feminists do not propose an outright "ban" on porn or any punishment for those who merely view information technology or corroborate of information technology; often, they propose some restrictions on particular things similar child porn, or suggest to allow people who are injure by porn to sue publishers and producers—non viewers—for damages. And then the arguer hasn't really scored whatsoever points; he or she has just committed a fallacy.

Tip: Be charitable to your opponents. State their arguments equally strongly, accurately, and sympathetically as possible. If y'all tin can knock downwards even the best version of an opponent's argument, and so you lot've actually achieved something.

Red herring

Definition: Partway through an argument, the arguer goes off on a tangent, raising a side upshot that distracts the audience from what'southward actually at stake. Often, the arguer never returns to the original issue.

Example: "Grading this exam on a curve would exist the almost fair thing to do. Afterward all, classes go more smoothly when the students and the professor are getting along well." Let'due south effort our premise-determination outlining to run across what'due south incorrect with this argument:

Premise: Classes get more smoothly when the students and the professor are getting along well.

Determination: Grading this exam on a curve would exist the nigh off-white thing to do.

When nosotros lay information technology out this fashion, it'southward pretty obvious that the arguer went off on a tangent—the fact that something helps people get along doesn't necessarily make it more fair; fairness and justice sometimes require us to practice things that cause conflict. But the audience may feel like the issue of teachers and students agreeing is important and be distracted from the fact that the arguer has not given any evidence equally to why a curve would be fair.

Tip: Try laying your premises and decision out in an outline-similar form. How many problems practise y'all see being raised in your argument? Can you lot explain how each premise supports the conclusion?

Imitation dichotomy

Definition: In imitation dichotomy, the arguer sets upwards the state of affairs and then it looks similar at that place are simply 2 choices. The arguer then eliminates i of the choices, so it seems that nosotros are left with only i option: the one the arguer wanted us to pick in the showtime place. But often there are really many different options, not just 2—and if we idea about them all, we might not exist so quick to choice the ane the arguer recommends.

Example: "Caldwell Hall is in bad shape. Either we tear information technology down and put up a new edifice, or we go on to risk students' safety. Obviously we shouldn't risk anyone's safety, and so nosotros must tear the building downwards." The statement neglects to mention the possibility that we might repair the edifice or find some way to protect students from the risks in question—for instance, if only a few rooms are in bad shape, perhaps we shouldn't concur classes in those rooms.

Tip: Examine your own arguments: if you lot're maxim that nosotros have to choose between simply two options, is that really so? Or are there other alternatives you haven't mentioned? If there are other alternatives, don't just ignore them—explain why they, too, should be ruled out. Although there's no formal name for it, assuming that there are simply three options, iv options, etc. when really in that location are more is similar to false dichotomy and should as well be avoided.

Begging the question

Definition: A complicated fallacy; it comes in several forms and can exist harder to discover than many of the other fallacies we've discussed. Basically, an argument that begs the question asks the reader to simply take the conclusion without providing real evidence; the argument either relies on a premise that says the aforementioned thing as the conclusion (which you lot might hear referred to equally "existence round" or "round reasoning"), or but ignores an important (but questionable) supposition that the statement rests on. Sometimes people utilise the phrase "beg the question" as a sort of general criticism of arguments, to mean that an arguer hasn't given very good reasons for a conclusion, merely that'south non the meaning we're going to discuss here.

Examples: "Active euthanasia is morally acceptable. Information technology is a decent, ethical thing to assist another man being escape suffering through expiry." Let'due south lay this out in premise-determination class:

Premise: Information technology is a decent, ethical matter to help another human being escape suffering through death.

Conclusion: Active euthanasia is morally adequate.

If we "translate" the premise, we'll run across that the arguer has really simply said the same thing twice: "decent, upstanding" means pretty much the same thing as "morally acceptable," and "help another human being escape suffering through death" means something pretty similar to "agile euthanasia." So the premise basically says, "active euthanasia is morally acceptable," just similar the determination does. The arguer hasn't notwithstanding given the states any real reasons why euthanasia is adequate; instead, she has left us asking "well, really, why do yous think active euthanasia is acceptable?" Her argument "begs" (that is, evades) the real question.

Hither's a second case of begging the question, in which a dubious premise which is needed to make the argument valid is completely ignored: "Murder is morally wrong. So active euthanasia is morally incorrect." The premise that gets left out is "active euthanasia is murder." And that is a debatable premise—over again, the argument "begs" or evades the question of whether active euthanasia is murder by simply not stating the premise. The arguer is hoping we'll only focus on the uncontroversial premise, "Murder is morally incorrect," and not discover what is existence causeless.

Tip: One way to attempt to avoid begging the question is to write out your bounds and conclusion in a short, outline-similar course. See if you find whatever gaps, any steps that are required to motion from i premise to the next or from the premises to the decision. Write down the statements that would fill up those gaps. If the statements are controversial and you've just glossed over them, you might be begging the question. Next, check to see whether whatsoever of your premises basically says the same matter as the conclusion (just in different words). If and so, you're probably begging the question. The moral of the story: y'all tin't but assume or use as uncontroversial prove the very thing you're trying to prove.

Equivocation

Definition: Equivocation is sliding between two or more different meanings of a single word or phrase that is of import to the statement.

Example: "Giving coin to charity is the right thing to do. And so charities have a right to our money." The equivocation here is on the word "right": "right" can mean both something that is correct or good (as in "I got the right answers on the examination") and something to which someone has a claim (equally in "everyone has a correct to life"). Sometimes an arguer volition deliberately, sneakily equivocate, often on words like "freedom," "justice," "rights," and so forth; other times, the equivocation is a mistake or misunderstanding. Either way, it's important that you lot use the main terms of your argument consistently.

Tip: Identify the virtually important words and phrases in your argument and ask yourself whether they could take more than than i meaning. If they could, exist sure you aren't slipping and sliding betwixt those meanings.

Then how do I find fallacies in my own writing?

Hither are some full general tips for finding fallacies in your own arguments:

• Pretend you disagree with the determination you're defending. What parts of the statement would now seem fishy to you? What parts would seem easiest to attack? Give special attending to strengthening those parts.
• Listing your main points; nether each 1, list the bear witness you take for information technology. Seeing your claims and evidence laid out this way may brand you realize that you have no proficient evidence for a particular claim, or information technology may help you expect more critically at the evidence you're using.
• Larn which types of fallacies you're especially prone to, and be careful to check for them in your piece of work. Some writers brand lots of appeals to say-so; others are more than likely to rely on weak analogies or ready straw men. Read over some of your old papers to see if at that place's a detail kind of fallacy you lot need to watch out for.
• Be aware that broad claims need more than proof than narrow ones. Claims that use sweeping words like "all," "no," "none," "every," "always," "never," "no one," and "everyone" are sometimes appropriate—but they crave a lot more proof than less-sweeping claims that utilise words like "some," "many," "few," "sometimes," "usually," and so forth.
• Double check your characterizations of others, especially your opponents, to be certain they are accurate and fair.

Tin can I get some practise with this?

Yes, you can. Follow this link to encounter a sample argument that'due south full of fallacies (and and then you tin can follow another link to get an explanation of each ane). So there's a more well-constructed argument on the aforementioned topic.

Works consulted

We consulted these works while writing this handout. This is not a comprehensive list of resources on the handout's topic, and nosotros encourage yous to do your own enquiry to find additional publications. Please do not use this listing every bit a model for the format of your own reference list, as it may not match the commendation style you are using. For guidance on formatting citations, delight see the UNC Libraries citation tutorial. We revise these tips periodically and welcome feedback.

Copi, Irving Thou., Carl Cohen, and Victor Rodych. 1998. Introduction to Logic. London: Pearson Educational activity.

Hurley, Patrick J. 2000. A Concise Introduction to Logic, 7th ed. Belmont, CA: Wadsworth.

Lunsford, Andrea A., and John J. Ruszkiewicz. 2016. Everything'south an Argument, 7th ed. Boston: Bedford/St Martin's.

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