Week 7 — Reasons That Miss: Testing Relevance in a Letter and an Ad — Traditional alternative (no AI)

Instructors: publish this instead of the adaptive version if you prefer, and unpublish or delete the adaptive one.

Assignment 7 of the term — catch reasons that miss the point, state an objection fairly and place it on a map, weigh an appeal to authority, and explain to someone new why a famous name and a taste test are not evidence about memory.

This week you learned to set a fallacy apart from a false premise, to run the relevance test, and to recognize the attacks on the person, the straw man, the appeals to fear, pity, and popularity, the red herring, and the appeal to unqualified authority. In this assignment you work four short problems on two illustrative texts, interpret each one, place an objection on an argument map as Week 2 taught you, and explain to someone who has never studied critical thinking why a famous name is not evidence. This week's lecture tutorial, quiz, discussion, and Argument Workshop practise the same ideas from other angles.

The task

Your first text is an illustrative letter to a town newsletter, with no real town or person behind it: "The town pool should stay open 2 extra hours each evening this summer. Each extra evening needs 3 lifeguards for those 2 hours, paid 19 dollars an hour. We can ignore the parks director's warning about the budget; he has never even swum a lap. The director says the extra hours would use money set aside for repairing the pool's pumps, but opponents want the town's kids stuck indoors all summer."

Your second text is an illustrative ad for a study drink, with no real product behind it: "Our study drink sharpens your memory: a famous singer swears by it! At a campus tasting, 42 of 60 students said they liked the taste. Don't be the one who fails a final because you skipped it."

Work these four problems, showing your arithmetic and quoting the sentences you use:

1. The letter says each extra evening needs 3 lifeguards for 2 extra hours. How many lifeguard hours does each extra evening need?
2. Using the lifeguard hours from Problem 1, how many dollars does each extra evening cost at 19 dollars an hour?
3. The ad says 42 of 60 students at the tasting said they liked the taste. What percentage of the students said they liked it?
4. Of the same 60 students, how many did not say they liked the taste?

Beside each answer, add one brief interpretation:

• Problem 1: name the fallacy in the letter's third sentence, run the relevance test on it (if that premise were true, would it bear on the conclusion?), and name the director's real reason for the warning.
• Problem 2: name the fallacy in the words "opponents want the town's kids stuck indoors all summer," state the director's real objection fairly in one sentence, and describe in words where that objection sits on an argument map of the letter and where the distorted version would land.
• Problem 3: name the fallacy in "a famous singer swears by it," run the three checks for an appeal to authority and say which one fails, and say whether the tasting percentage you found bears on whether the drink sharpens memory.
• Problem 4: name the appeal in the ad's last sentence and say what it offers in place of evidence, then write the message to the friend described below.

Explain it to a non-expert

A friend who has never studied logic sees the ad and asks, "A famous singer drinks it and most students liked it, so it must help on exams, right?" Write a 3–5 sentence message that explains in everyday words why neither the singer nor the tasting shows that the drink sharpens memory, reports the percentage you found and how many students did not say they liked the taste, and names one limit: the ad offers no evidence about memory at all, so whether the drink helps is still unknown. Explain any technical term in everyday words. More than one good answer is possible.

For a different, ungraded example, imagine a shoe ad that says "A star basketball player wears these, so they'll make you faster." Model answer: "The player knows basketball, not how shoes affect speed, so wearing them isn't evidence they make anyone faster. If the player is paid to wear them, that is one more reason to look for an independent test. Before you buy, look for a comparison of runners in these shoes and runners in other shoes."

Use that pattern for the friend, with your own wording and evidence.

Show your arithmetic, write each fallacy name and the director's real objection out in full, and quote the sentences you use. A reader should be able to reproduce every number you report, and find every quoted sentence in the letter or the ad, without guessing which values, steps, or sentences you used.

Deliverables

Submit a single report containing:

• the four answers, each with the arithmetic shown and the brief interpretation the task names for that problem;
• your message to the friend, explaining why neither the singer nor the tasting shows the drink sharpens memory, reporting the percentage and how many students did not say they liked the taste, and naming one limit; and
• a one-line restatement of the values you used (the lifeguards, the extra hours, the hourly wage, and the students who liked the taste out of all students at the tasting), so your answers are reproducible.

Keep it to roughly one page. Clear and correct beats long.

Choose how you show it. Present your report as written text, or as a recorded audio or video explanation of about three minutes with a transcript, or as a labelled sketch of the letter's argument map that shows the conclusion, the director's real objection as an arrow marked against, and the distorted version off the map, with a short note that says each verdict in words. Every form is graded by the same scoring criteria. Submit in any accessible file type or as a link; a recorded response may be submitted as audio or video with a transcript, or as text.

How you'll be graded

The full analytic rubric is attached to this assignment in Canvas.

Academic integrity and AI use

This version is designed to be completed without AI: do the computations, the interpretations, the map, and the writing yourself, without a chatbot or other AI tool. Quote the letter and the ad only as they are printed here, word for word. Submitting AI-generated work as your own, or copying another student's work, is an integrity violation under the course policy.

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