Week 13 · Chapter

Chapter 13 — Argument, Reasoning & Logical Fallacies

Public Speaking Free sample edition

The module's primary reading · ~40–50 minutes · Objective 7 (compose and deliver an informative speech that teaches without an agenda and a persuasive speech that moves an audience ethically using the three appeals (ethos, pathos, logos), sound reasoning (inductive, deductive, causal, analogical; claim, evidence, warrant), and an awareness of the common logical fallacies, on a topic from the pinned non-partisan roster), Objective 3 (choose and narrow a topic, write a general purpose, a well-formed specific purpose, and a central idea, and support the speech with credible examples, statistics, and testimony that are evaluated for credibility and cited aloud in a complete oral citation naming who, what, and when — never fabricated, never plagiarized) · Read it first this week; the lecture, the slide deck, the tutorial, the quiz, and the Speech Workshop all build on it.

In plain language

This week you look under the hood of an argument (a claim plus the reasons and evidence offered for it). You learn four ways of reasoning (getting from evidence to a conclusion) and how to tell a strong path from a shaky one. You learn to draw any argument as a small map whose most important part is the warrant (the unstated link between your evidence and your claim). And you learn 12 fallacies, the flaws that make an argument look stronger than it is, so you can keep them out of your own speech and catch them in someone else's.

Why you already care about this

Picture a student-government meeting in a library basement on a weeknight. About 20 students sit at study tables, deciding whether to allow snacks in the library. The first speaker stands up and says, "I asked three friends who eat at their desks, and all three keep them spotless, so every student will keep the library clean." Heads nod. The second speaker says, "If we allow coffee, next it's pizza, and soon the library is a food court." More heads nod. The scene is illustrative and attributed to no one.

Both speakers sounded sure of themselves. Both got nods. And both arguments break the moment you look at them closely. Three friends are not every student. Coffee does not lead to a food court unless someone shows that each step will happen. You have heard arguments like these in group chats, in meetings at work, and in ads, and you have probably made one or two yourself.

Last week you learned to move an audience with the three appeals. This week you learn to check whether the logos part of that move, the reasoning, holds weight. That skill works in two directions: it makes your own persuasive speech harder to knock down, and it makes you a sharper listener when someone else is trying to persuade you.

By the end of this chapter you will be able to:

name the four types of reasoning this course teaches and find each one inside a real argument;
write a syllogism and test causal and analogical reasoning for the classic weak spots;
map an argument with Toulmin's model and tell the warrant from the evidence;
define and spot the 12 fallacies this course names, and untangle the mix-ups that trip almost everyone;
build your own persuasive claim as a full argument and catch a chatbot that labels a fallacy wrong.

Carry this sentence with you: the evidence is what you cite — the warrant is why it counts.

Where we are

Already covered: Week 3 gave you the claim's ancestors, the specific purpose and the central idea; Week 4 gave you evidence and the oral citation; Week 12 turned the running speech into a persuasive policy claim built on the three appeals.
This week: the four types of reasoning, Toulmin's map of an argument, the 12 fallacies this course names, and the drills that put them to work.
How they connect: logos is the appeal to evidence and reasoning, and this week shows what makes reasoning sound or unsound, so your persuasive speech's case can stand up to a skeptical listener.
Where we're going next: Week 14, Special-Occasion & Small-Group / Team Communication, turns from arguing a case to fitting a moment and working in a group.

Here is what this week leans on. Week 4 taught you that a complete oral citation names who, what, and when before the evidence; that is still the form your evidence takes, and Toulmin's model now gives it a place in a larger structure. Week 4 also taught you the difference between expert testimony (from someone qualified in the relevant field) and lay testimony (from someone with firsthand experience), which becomes the cure for one of this week's fallacies. Week 12 gave you the running speech's claim: "Our campus dining hall should run a two-week plate-waste audit before deciding whether to remove trays." It also previewed false dilemma as the "decide now or lose everything" form of false urgency. This week that preview gets its full name.

1. Four types of reasoning: find the path from evidence to claim

Think about how you decide a new coffee shop is good. Maybe you went three times and every drink was great, so you trust the place. Maybe a friend told you that every shop roasting its own beans is good, and this one roasts its own. Maybe you noticed your afternoons got better after you switched shops. Maybe you liked the shop's sister location across town, so you figure this one is similar. Those are four different paths from evidence to a conclusion, and each one can go wrong in its own way.

Reasoning is the process of moving from evidence or principles to a conclusion; this course names four types: inductive, deductive, causal, and analogical. Conventions differ here. Some treatments file causal, sign, and analogical reasoning under induction and treat deduction on its own, so this course teaches its grouping in words and never asks you to recite how many types there are.

Inductive reasoning moves from specific cases to a general conclusion, so its strength depends on how many cases there are and how typical they are.
Deductive reasoning moves from a general principle to a specific conclusion, so the conclusion must hold if the principle and the case are both true.
A syllogism is the classic form of deductive reasoning: two premises, one general and one specific, followed by the conclusion they lead to. A premise is a statement offered as a starting point in an argument, which the conclusion is drawn from.
Causal reasoning claims one thing produces another; it must show more than that one thing came after the other or that the two rise and fall together. A correlation is a pattern in which two things tend to change together, which can happen without either one causing the other.
Analogical reasoning says two cases alike in known ways are likely alike in another way, which holds only when they are alike in the ways that matter.

You met the word analogy in Week 11, as a clarity strategy that explains something new by comparing it to something familiar. Analogical reasoning goes one step further: it uses the comparison as proof. That extra step is where it can break.

Worked example — four types inside one claim. The running speech is illustrative and attributed to no one. Its claim is "Our campus dining hall should run a two-week plate-waste audit before deciding whether to remove trays." Here is how each type of reasoning shows up inside it.

First, deductive. Written as a syllogism, the speech's case looks like this:

Premise 1, the general principle: "A campus should measure a change's effect before adopting it when the best available study found no significant effect."
Premise 2, the specific case: the best available study on trays found no significant reduction in food waste.
Conclusion: our campus should measure before removing trays.

That is 2 premises + 1 conclusion = 3 statements. If both premises are true, the conclusion follows.

Second, causal. Does removing trays cause less waste? The speech answers with oral citation 2:

"In a study published in the journal Sustainability in December 2022, researchers Wenhao Zhang and Junehee Kwon found that a week without trays in a university dining hall, compared with a week with trays, reduced how much food diners took but did not show a significant reduction in food waste."

Diners took less food after the trays left, but a drop in waste did not show up. The speech does not claim a cause the study did not find. That restraint is causal reasoning done well.

Third, analogical. Copying another campus's tray decision assumes the two dining halls are alike in the ways that matter: the menu, the diners, the serving line. The qualifier "in dining halls like ours" says that assumption out loud instead of hiding it.

Fourth, inductive. One study's two weeks in one dining hall are specific cases. Turning them into "trayless never works anywhere" would generalize too far, so the speech asks for its own measurement.

The sort, counted: 4 types of reasoning, each found once in the running speech. In words: one persuasive claim can rest on several kinds of reasoning at once, and each kind has its own test.

Here is a caveat. A syllogism is only as good as its premises. A perfectly shaped syllogism with a false first premise leads, perfectly, to a false conclusion. So the form tells you whether the conclusion follows; the evidence tells you whether the premises are true.

Misconception check. Students often swap inductive and deductive reasoning, because both involve "general" and "specific" and the words sound alike. The cure is the direction of travel. Inductive reasoning starts with cases and ends with a general conclusion: three great drinks, so the shop is good. Deductive reasoning starts with a general principle and ends with a specific conclusion: every shop that roasts its own beans is good, this one does, so this one is good. A second classic slip is treating sequence or correlation as cause. If B happened after A, that alone does not show A caused B.

2. Map the argument: claim, evidence, and warrant

Imagine a friend says, "You should take the early bus." You ask why. They say, "It's never crowded." You nod, because you both assume something neither of you said: that a less crowded bus is a better bus. That unspoken assumption is the hinge of the whole argument. If you love the late bus because your best friend rides it, the hinge does not hold for you, and the argument fails.

Stephen Toulmin gave that hinge a name. Toulmin (1958), The Uses of Argument, laid out the parts of an everyday argument. Toulmin's model is Stephen Toulmin's 1958 layout of an argument's parts: claim, evidence (grounds), and warrant, which this course keys, plus backing, qualifier, and rebuttal. Toulmin's model is a classroom model, a simplification you can hold in one hand, and not every real argument states all six parts.

A claim is the statement an argument asks the audience to accept, such as a policy a persuasive speech proposes.
Evidence is, in Toulmin's model, the grounds offered for a claim: supporting material such as a study or statistic, cited aloud with who, what, and when.
A warrant is the usually unstated principle that makes the evidence count as proof of the claim; it is the link between them, not a fact that is cited.
Backing is, in Toulmin's model, the support offered for the warrant itself when an audience might doubt the principle.
A qualifier is, in Toulmin's model, the words that limit how strongly or how widely a claim applies, such as "for a two-week trial" or "in dining halls like ours."
A rebuttal is, in Toulmin's model, the condition under which the claim would not hold, stated so the speaker can account for it, such as "unless the audit costs more than the trial."

The counting is easy to keep straight: 6 parts named, and the course keys 3 of them, the claim, the evidence, and the warrant. That leaves 6 − 3 = 3 parts named but not keyed: backing, qualifier, and rebuttal.

Worked example — the running speech, mapped. Here is the running speech's persuasive claim, part by part.

The running speech's persuasive claim mapped onto five of Toulmin's six parts
Part	What the running speech says
Claim	"Our campus dining hall should run a two-week plate-waste audit before deciding whether to remove trays."
Evidence	Oral citation 1 (the U.S. Department of Agriculture's Food Waste FAQ page) and oral citation 2 (Zhang and Kwon's study in Sustainability, December 2022)
Warrant	"a campus should measure a change's effect before adopting it when the best available study found no significant effect"
Qualifier	"for a two-week trial" and "in dining halls like ours"
Rebuttal	"unless the audit costs more than the trial"

Here is oral citation 1 in full, exactly as the speech says it:

"According to the U.S. Department of Agriculture's Food Waste FAQ page, which draws on the department's Economic Research Service, between 30 and 40 percent of the food supply in the United States goes to waste."

Count the map: 1 claim + 2 pieces of evidence + 1 warrant + 2 qualifiers + 1 rebuttal = 7 statements, across 5 of the 6 parts. Backing is the one part the course's map leaves unstated. In words: the map makes visible the one sentence most speakers never say, the warrant, so you can check whether it holds.

Notice what the qualifier does for your credibility. "For a two-week trial" admits the audit is a test, not a permanent rule. "In dining halls like ours" admits that a study from another dining hall may not transfer. A listener who doubts you hears a speaker who already knows the limits. That is ethos and logos working together.

Notice what the rebuttal does too. "Unless the audit costs more than the trial" names the one condition that would sink the claim. Week 12 asked you to acknowledge the strongest counter-argument; the rebuttal is where that honesty lives inside the argument itself.

Warrant versus evidence. Oral citation 2 is evidence, because anyone can check it at the source. "Measure before adopting" is the warrant, because it is the principle that turns the study into a reason for the audit. Ask yourself one question: could a listener look this up? If yes, it is evidence. If it is the reason the evidence matters, it is the warrant.

Misconception check. Students often point to a statistic and call it the warrant, because the statistic feels like the strongest part of the argument. But a statistic is evidence. The warrant is the link: the principle that says why that statistic should move the listener toward this claim. The cure is the look-it-up test above. When a listener rejects an argument whose evidence is solid, the warrant is usually where they got off the bus.

3. Fallacies that break the support

Think of a chair with a cracked leg. From across the room it looks like any other chair. Sit on it and you find out. A fallacy is a flaw in reasoning that makes an argument look stronger than it is, usually by breaking the link between the evidence and the claim. A fallacious argument looks fine from across the room.

This course names 12 fallacies. Other treatments name more or fewer, so "the" number of fallacies is taught in words, and no quiz asks you to count them. For study, this chapter sorts them into two groups of six. The groups are this course's study aid, not a standard taxonomy. The first six break an argument's support: the evidence is too thin, the cause is assumed, the comparison does not fit, or the source has no standing.

Each example below is illustrative, neutral, and attributed to no one. Fallacies are always taught on invented examples in this course, never on a real public figure.

Hasty generalization is a fallacy that draws a general conclusion from too few or too unusual cases; it is an error about sample size. Example: "I asked three friends who eat at their desks, and all three keep them spotless, so every student will keep the library clean."
False cause is a fallacy that treats one thing as the cause of another because it came first or because the two occur together; it is an error about causation, also called post hoc. Example: "Sales at the café went up the month the new manager started, so the new manager caused the rise."
Weak analogy is a fallacy that compares two cases that differ in ways that matter to the conclusion being drawn. Example: "A pizza shop guarantees its delivery time, so campus security should guarantee its response time too." Both show up at your door, but an emergency is not a pizza order.
Appeal to ignorance is a fallacy that treats a lack of proof as proof, claiming something is false because it has not been shown true, or true because it has not been shown false. Example: "No one has proven the bike-helmet loaner program made riders safer, so it made no difference."
False authority is a fallacy that offers a person's opinion as proof when that person has no expertise in the field the claim is about. Example: "A popular gaming streamer says this bike helmet is the safest on the market, so it is."
Bandwagon is a fallacy that treats a claim as true or a choice as right because many people believe it or do it. Example: "Everyone on my floor already snacks in the library, so it must be fine."

Worked example — two support fallacies fixed. Take the café manager. Sales rose the month she started. To turn that into sound causal reasoning, a speaker would need to rule out other explanations: a new menu, a holiday rush, a nearby café closing. Without that, the honest sentence is "sales rose the month the new manager started," and nothing more.

Now take the streamer and the helmet. The fix comes straight from Week 4. Replace false authority with expert testimony from someone qualified in helmet safety, and cite that source aloud as who, what, and when, before the evidence. Fame in one field is not expertise in another.

Misconception check. Students often swap false cause and hasty generalization, because both sound like "jumping to conclusions." They jump in different directions. Hasty generalization is wrong about sample size: too few cases for a general claim. False cause is wrong about causation: one thing came first, so it must have caused the other. Ask one question to sort them: is this argument about how many cases, or about what caused what? Three friends and every student is a sample problem. A new manager and rising sales is a cause problem.

Pause and reflect. Choose one option and jot two or three sentences.

(a) Think of a time you believed something because "everyone" seemed to believe it. Which support fallacy was at work, and what evidence would have settled it?

(b) Think of an ad or a post that used a famous person to sell something outside that person's field. Which support fallacy was it, and whose testimony would have counted?

4. Fallacies that dodge or rig the argument

Picture a neighborhood meeting about a later closing time for the public library. One neighbor makes a careful case. The next speaker never answers it. Instead, they mock the first neighbor's job, or describe a much sillier version of the proposal, or start talking about parking. The argument did not lose. It got dodged. The scene is illustrative and attributed to no one.

The second six fallacies dodge the real argument or rig the choice. Each example is illustrative and attributed to no one.

Ad hominem is a fallacy that attacks the person making an argument and offers that attack as a reason to reject the argument. Example: "Don't listen to his plan to speed up security response times; he got a parking ticket last month."
Straw man is a fallacy that attacks a distorted or exaggerated version of an opponent's position instead of the position itself. Example: a student proposes allowing covered drinks in the library, and the reply is, "So you think spills on the rare-book shelves don't matter."
Red herring is a fallacy that changes the subject to a different issue, so the original question is never answered. Example: asked why security response times are slow, a speaker talks about the new parking garage.
False dilemma is a fallacy that offers only two options when more exist, so the listener feels forced to pick one of them. Example: "Either we ban all food in the library, or the carpets will be ruined."
Slippery slope is a fallacy that claims one step will set off a chain of worse steps without evidence that each step will follow. Example: "If we allow coffee, next it's pizza, and soon the library is a food court."
Begging the question is a fallacy that uses the conclusion as one of its own premises, so the argument goes in a circle; it does not mean raising a question. Example: "The new manager's plan will work because it is a plan that works."

Week 12 met false dilemma in disguise, as the "decide now or lose everything" form of false urgency. Now you can name it directly: two doors offered when the room has more.

Worked example — three dodges, one proposal. Take the covered-drinks proposal and watch three replies dodge it in three different ways.

"She's only proposing this because she drinks coffee all day." That attacks the person: ad hominem.
"So she wants the library to be a café." That attacks a version of the proposal she never made: straw man.
"Speaking of the library, the printers are always broken." That changes the subject: red herring.

The honest reply engages the actual proposal: "Covered drinks still spill sometimes. Could we pilot it on one floor first?" That reply has a claim, a reason, and a qualifier. In words: a fair answer argues with the position someone actually holds.

Misconception check. Students often think ad hominem means "insulting someone." An insult on its own is rude, not a fallacy. Ad hominem is an attack on the person offered as a reason to reject the argument. Students also mix up straw man and red herring. A straw man stays on the topic but distorts the position; a red herring leaves the topic. And many students believe all emotional appeals are fallacies. They are not. Pathos is legitimate when it is relevant and proportionate; it becomes a fallacy when it substitutes for evidence. The running speech's compost-bin scene sits beside a real study, so it is pathos doing its honest job.

One more honesty note. Naming a fallacy out loud in a speech ("that's a straw man!") can sound like a gotcha instead of an answer. Often the stronger move is to restate the other side's real position fairly and answer that. Your listeners will notice which speaker played fair.

5. Run the drills and check the machine

A mechanic who spots a worn brake pad is useful. A mechanic who can also replace it is the one you call back. This section runs two drills: spotting a fallacy, and building an argument that has none.

Worked example — the spot-the-fallacy drill. Four fresh items, each illustrative and attributed to no one:

The four spot-the-fallacy items, each with its fallacy and the reason for the label
Item	What the speaker says	The fallacy	Why
Campus security's response time	Asked why responses are slow, the speaker talks about the new parking garage	Red herring	The subject changed
A new manager and rising sales	"Sales at the café went up the month the new manager started, so the new manager caused the rise."	False cause	Coming first is not causing
Food in the library	"Either we ban all food in the library, or the carpets will be ruined."	False dilemma	Two options offered when more exist
Helmets and safety	"A popular gaming streamer says this bike helmet is the safest on the market, so it is."	False authority	Fame in another field is not expertise

Add the 2 fallacies from the opening meeting, the hasty generalization and the slippery slope: 2 + 4 = 6 fallacy examples labelled.

The build-the-argument drill. Take one main point of your own persuasive speech, on a topic from the course's roster, and write five lines: your claim, your evidence as a complete oral citation, your warrant, a qualifier, and a rebuttal. Then read your warrant aloud and ask whether a skeptical listener would accept it. If not, you need backing, a narrower claim, or a different warrant.

Check the machine

A chatbot can help you practice, but it often blurs exactly the distinctions this week teaches.

Worked example — a chatbot labels the new-manager item. The exchange is illustrative and names no product. Asked to label item 2, a chatbot answers, "This is a hasty generalization, because it draws a conclusion from limited evidence and assumes the manager caused the increase." Asked to check the running speech, it adds, "The compost-bin scene is an appeal-to-emotion fallacy; cut it."

Check each line against the definitions.

Problem 1, a wrong label. Item 2 is false cause, because the error is about causation, not sample size.
Problem 2, a blended explanation. "Limited evidence" belongs to hasty generalization; "assumes the manager caused" belongs to false cause. Explaining both at once teaches the mix-up instead of curing it.
Problem 3, a legitimate appeal called a fallacy. The compost-bin scene is labelled illustrative, relevant, and proportionate, and it sits beside oral citation 2, so it is legitimate pathos.

Problems caught: 1 wrong label + 1 blended explanation + 1 legitimate appeal called a fallacy = 3. In words: a confident label is not a correct one, so check every label against the definition before you trust it.

Misconception check. Students often trust a chatbot's fallacy label because it arrives with a definition attached. That is tempting, because the explanation sounds like a textbook. But a chatbot can name the wrong fallacy and still sound sure, and it often explains two fallacies as if they were one. The cure is the sorting question from Section 3, asked by you: is this about how many cases, or about what caused what? You make the final call, not the tool.

Key terms

Argument — A claim together with the reasons and evidence offered to show that the claim should be accepted. (first used: 1. Four types of reasoning: find the path from evidence to claim)
Reasoning — The process of moving from evidence or principles to a conclusion; this course names four types: inductive, deductive, causal, and analogical. (first used: 1. Four types of reasoning: find the path from evidence to claim)
Inductive reasoning — Reasoning that moves from specific cases to a general conclusion, so its strength depends on how many cases there are and how typical they are. (first used: 1. Four types of reasoning: find the path from evidence to claim)
Deductive reasoning — Reasoning that moves from a general principle to a specific conclusion, so the conclusion must hold if the principle and the case are both true. (first used: 1. Four types of reasoning: find the path from evidence to claim)
Syllogism — The classic form of deductive reasoning: two premises, one general and one specific, followed by the conclusion they lead to. (first used: 1. Four types of reasoning: find the path from evidence to claim)
Premise — A statement offered as a starting point in an argument, which the conclusion is drawn from. (first used: 1. Four types of reasoning: find the path from evidence to claim)
Causal reasoning — Reasoning that claims one thing produces another; it must show more than that one thing came after the other or that the two rise and fall together. (first used: 1. Four types of reasoning: find the path from evidence to claim)
Correlation — A pattern in which two things tend to change together, which can happen without either one causing the other. (first used: 1. Four types of reasoning: find the path from evidence to claim)
Analogical reasoning — Reasoning that says two cases alike in known ways are likely alike in another way, which holds only when they are alike in the ways that matter. (first used: 1. Four types of reasoning: find the path from evidence to claim)
Toulmin's model — Stephen Toulmin's 1958 layout of an argument's parts: claim, evidence (grounds), and warrant, which this course keys, plus backing, qualifier, and rebuttal. (first used: 2. Map the argument: claim, evidence, and warrant)
Claim — The statement an argument asks the audience to accept, such as a policy a persuasive speech proposes. (first used: 2. Map the argument: claim, evidence, and warrant)
Evidence — In Toulmin's model, the grounds offered for a claim: supporting material such as a study or statistic, cited aloud with who, what, and when. (first used: 2. Map the argument: claim, evidence, and warrant)
Warrant — The usually unstated principle that makes the evidence count as proof of the claim; it is the link between them, not a fact that is cited. (first used: 2. Map the argument: claim, evidence, and warrant)
Backing — In Toulmin's model, the support offered for the warrant itself when an audience might doubt the principle. (first used: 2. Map the argument: claim, evidence, and warrant)
Qualifier — In Toulmin's model, the words that limit how strongly or how widely a claim applies, such as "for a two-week trial" or "in dining halls like ours." (first used: 2. Map the argument: claim, evidence, and warrant)
Rebuttal — In Toulmin's model, the condition under which the claim would not hold, stated so the speaker can account for it, such as "unless the audit costs more than the trial." (first used: 2. Map the argument: claim, evidence, and warrant)
Fallacy — A flaw in reasoning that makes an argument look stronger than it is, usually by breaking the link between the evidence and the claim. (first used: 3. Fallacies that break the support)
Hasty generalization — A fallacy that draws a general conclusion from too few or too unusual cases; it is an error about sample size. (first used: 3. Fallacies that break the support)
False cause — A fallacy that treats one thing as the cause of another because it came first or because the two occur together; it is an error about causation, also called post hoc. (first used: 3. Fallacies that break the support)
Weak analogy — A fallacy that compares two cases that differ in ways that matter to the conclusion being drawn. (first used: 3. Fallacies that break the support)
Appeal to ignorance — A fallacy that treats a lack of proof as proof, claiming something is false because it has not been shown true, or true because it has not been shown false. (first used: 3. Fallacies that break the support)
False authority — A fallacy that offers a person's opinion as proof when that person has no expertise in the field the claim is about. (first used: 3. Fallacies that break the support)
Bandwagon — A fallacy that treats a claim as true or a choice as right because many people believe it or do it. (first used: 3. Fallacies that break the support)
Ad hominem — A fallacy that attacks the person making an argument and offers that attack as a reason to reject the argument. (first used: 4. Fallacies that dodge or rig the argument)
Straw man — A fallacy that attacks a distorted or exaggerated version of an opponent's position instead of the position itself. (first used: 4. Fallacies that dodge or rig the argument)
Red herring — A fallacy that changes the subject to a different issue, so the original question is never answered. (first used: 4. Fallacies that dodge or rig the argument)
False dilemma — A fallacy that offers only two options when more exist, so the listener feels forced to pick one of them. (first used: 4. Fallacies that dodge or rig the argument)
Slippery slope — A fallacy that claims one step will set off a chain of worse steps without evidence that each step will follow. (first used: 4. Fallacies that dodge or rig the argument)
Begging the question — A fallacy that uses the conclusion as one of its own premises, so the argument goes in a circle; it does not mean raising a question. (first used: 4. Fallacies that dodge or rig the argument)

Summary

An argument is a claim plus the reasons and evidence offered for it.
Inductive: cases to a general conclusion. Deductive: a general principle to a specific conclusion.
A syllogism is two premises and a conclusion; it is only as good as its premises.
Sequence and correlation are not cause.
An analogy proves something only when the cases match in the ways that matter.
Toulmin's model keys claim, evidence, and warrant, and names backing, qualifier, and rebuttal.
Evidence is what you cite; the warrant is why it counts.
False cause is about causation; hasty generalization is about sample size.
Ad hominem attacks the person, straw man distorts the position, red herring changes the subject.
Begging the question uses the conclusion as a premise.
Pathos is legitimate when relevant and proportionate; it is a fallacy when it replaces evidence.
Check every chatbot fallacy label against the definition.

Check your understanding

Work these before looking at the answers — they are ungraded, and the answers (with reasoning) are at the bottom of the page.

A robotics-club captain says, "We won 5 of our 6 matches using the new wheels, so the new wheels win matches." Name the type of reasoning, then say which fallacy the claim risks and what evidence would make it stronger.
A clinic volunteer argues, "Our waiting room should add a second sign-in tablet, because last month 40 visitors waited more than ten minutes to sign in." Map the argument: name the claim, the evidence, and a warrant that links them.
Label each illustrative line with its fallacy: (a) "Either we cancel the garden workday or we work in the rain." (b) "You can't trust her budget numbers; she drives an old car." (c) "My cousin swears by this tutoring app, and he's a chef, so it must work."
A study group counts its practice-quiz items: 7 labelled correctly as false cause, 3 labelled as hasty generalization that were really false cause. How many items were really false cause, and which question would have sorted the 3 misses?

Answers (worked reasoning — read after attempting)

It is inductive reasoning, from 6 specific matches to a general conclusion, and it leans on causal reasoning too. It risks false cause: the wins came after the new wheels, but a new driver, easier opponents, or more practice could explain them. Stronger evidence would compare matches with and without the new wheels against similar opponents. The honest version is "we won 5 of 6 matches after switching wheels."
Claim: the waiting room should add a second sign-in tablet. Evidence: last month 40 visitors waited more than ten minutes to sign in, which should be cited aloud with who counted it and when. Warrant: when many visitors wait too long at one step, adding capacity at that step should shorten the wait. The warrant is not stated in the volunteer's sentence; it is the principle that makes the count a reason for the tablet.
(a) False dilemma: two options offered when more exist, such as moving the workday to a dry morning. (b) Ad hominem: an attack on the person offered as a reason to reject her numbers; the car says nothing about the budget. (c) False authority: a chef's opinion is not expertise in tutoring, and one cousin's experience is also a hasty generalization.
7 + 3 = 10 items were really false cause. The sorting question is "is this argument about how many cases, or about what caused what?" All 3 misses were about cause, so they were false cause. That is 7 versus 10 correct before sorting, so asking the question would have caught 3 more labels.

Next up in this module: the Readings & Resources page, the lecture tutorial, the practice set, and the quiz; next week the course turns to special-occasion speaking and small-group work, where the same honest reasoning helps a group reach a decision.

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