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PHIL 347 Critical Reasoning

Week 5 Guided Learning Activity: Relevance and Fallacies

Directions: Type the letter answer into Canvas. You may also include the whole line. The letter

comes before the line or sentence

Example:

[A] Paris is the biggest city in France. [B] It is a major cultural center with many famous

museums. [C] The most famous of these museums is the Louvre.

In this passage, A = Paris is the biggest city in France. B = It is a major cultural center with many

famous museums. C = The most famous of these museums is the Louvre.

Section 1: Relevance

Fallacies are mistakes in reasoning. Before we can spot mistakes, we need to understand what

counts as relevant. A positively relevant claim gives a reason to believe something. A negatively

relevant claim gives a reason not to believe something. Read pages 122–124 before starting this

section.

Passage:

The issue is whether Jamal should buy an electric bike

[A] Jamal enjoys cycling for exercise and commuting.

[B] His city has limited bike lanes, making some routes unsafe.

[C] He recently bought a new car that he rarely drives.

[D] Jamal works long hours and sometimes struggles to find time for exercise.

[E] The local bike shop is offering a discount on electric bikes this month.

[F] Friends who own electric bikes say they make commuting faster and less tiring.

[G] His apartment building has limited storage space for bicycles.

Question 1: Line A is

a. Positively relevant

b. Negatively relevant

c. Irrelevant

Question 2: Line B is

a. Positively relevant

b. Negatively relevant

c. Irrelevant

Question 3: Line C is

a. Positively relevant

b. Negatively relevant

c. Irrelevant

Question 4: Line D is

a. Positively relevant

b. Negatively relevant

c. Irrelevant

Question 5: Line E is

a. Positively relevant

b. Negatively relevant

c. Irrelevant

Section 2: Getting Personal

Critical thinking requires separating a person’s argument from the person themselves. While

we’re wired to evaluate people, this can get in the way of evaluating logic. Review pages 125–

130 before starting.

Passage:

[A] Don’t subscribe to StreamPlus — the CEO wears designer suits and obviously doesn’t care

about regular people.

[B] Also, their most popular competitor, FlixZone, has had a few outages, so maybe all

streaming services are unreliable.

[C] StreamPlus claims that its algorithm recommends the best shows, but you are sure to get

viruses that will steal your identity

[D] StreamPlus’s low prices are just designed to rope you in. Later, they will increase prices.

[E] Try CineWorld instead — sure, it loads more slowly sometimes, but at least it didn’t crash

during last night’s premiere.

Question 6: Line A is

a. Ad hominem

b. Attacking the motive

c. Look who’s talking (tu quoque)

d. Two wrongs don’t make a right

e. Scare tactics

Question 7: Line B is

a. Ad hominem

b. Attacking the motive

c. Look who’s talking (tu quoque)

d. Two wrongs don’t make a right

e. Scare tactics

Question 8: Line C is

a. Ad hominem

b. Attacking the motive

c. Look who’s talking (tu quoque)

d. Two wrongs don’t make a right

e. Scare tactics

Question 9: Line D is

a. Ad hominem

b. Attacking the motive

c. Look who’s talking (tu quoque)

d. Two wrongs don’t make a right

e. Scare tactics

Question 10: Line E is

a. Ad hominem

b. Attacking the motive

c. Look who’s talking (tu quoque)

d. Two wrongs don’t make a right

e. Scare tactics

Section 3: Changing the Subject

Straw man and red herring fallacies twist arguments or distract from the issue. Read pages 132–

133 before continuing.

Dialogue:

Taylor: We should encourage visitors to use reusable containers instead of disposable plastic at

the beach to reduce pollution.

Morgan: (A) So you want to make everyone bring their own containers and ban ice cream

cones? That’s extreme.

Taylor: (B) No, just suggesting alternatives to single-use plastics for snacks and drinks.

Morgan: But even if we reduce plastics, seagulls will still scatter trash everywhere—it won’t

really solve pollution.

Taylor: (C) Honestly, the bigger issue is that people leave food wrappers behind, which attracts

wildlife. That’s what we should focus on.

Morgan: (D) You’re just trying to change the subject from the real problems, like overcrowded

beaches and insufficient lifeguards.

Taylor: (E) The goal is to reduce plastic waste; that doesn’t mean ignoring other beach

management issues.

Question 11: Line A is

a. Straw man

b. Red herring

c. Neither

Question 12: Line B is

a. Straw man

b. Red herring

c. Neither

Question 13: Line C is

a. Straw man

b. Red herring

c. Neither

Question 14: Line D is

a. Straw man

b. Red herring

c. Neither

Question 15: Line E is

a. Straw man

b. Red herring

c. Neither

Section 4: Fallacies of Evidence

These fallacies involve improper use or interpretation of evidence. Read pages 143–154 before

doing this section.

Dialogue:

Lee: I think installing smart thermostats in our apartment building could save energy and reduce utility

bills.

Jordan: (A) If we install a few smart thermostats, soon every appliance will be automated, and we’ll lose

control over everything in our homes!

Lee: That’s not the case. Smart thermostats can be managed individually and don’t take over other

devices.

Jordan: (B) If smart thermostats really saved energy, don’t you think all buildings would already have

them? don’t save energy.

Lee: Studies show that smart thermostats generally help reduce energy usage when programmed

correctly.

Jordan: (C) Last month, my neighbor installed a smart thermostat and the heating bill went up, so these

devices clearly

Lee: (D) So either we don’t install anything, or our building will be fully automated and out of control

Jordan: (E) A few people I know who installed smart devices have had constant tech problems, so all

smart home tech must be unreliable.

Question 16: Line A is

a. Appeal to ignorance

b. Post hoc fallacy

c. Hasty generalization

d. Slippery slope

e. False alternative

Question 17: Line B is

a. Appeal to ignorance

b. Post hoc fallacy

c. Hasty generalization

d. Slippery slope

e. False alternative

Question 18: Line C is

a. Appeal to ignorance

b. Post hoc fallacy

c. Hasty generalization

d. Slippery slope

e. False alternative

Question 19: Line D is

a. Appeal to ignorance

b. Post hoc fallacy

c. Hasty generalization

d. Slippery slope

e. False alternative

Question 20: Line E is

a. Appeal to ignorance

b. Post hoc fallacy

c. Hasty generalization

d. Slippery slope

e. False alternative