Critical Reasoning – Lecture 1 Comprehensive Notes

Course Logistics & Resources

• Instructor

  • Prof. Mary Gregg (pronouns: she/her/hers)

  • E-mail: mary.gregg@yonsei.ac.kr

• Core Links (all clickable in the PDF version you generate)

  • Syllabus (full): see course LMS

  • Glasses photo credit: https://depositphotos.com/stock-photos/glasses.html

• Offices & Academic Support

  • Office for Students with Disabilities (OSD)

  • Location: Room 203, Student Union Building (Bldg 207)

  • Tel: 02\text{-}2123\text{-}3633 / 3634

  • E-mail: ablecenter@yonsei.ac.kr (English service available)

  • Homepage: https://ablecenter.yonsei.ac.kr/ablecenter1 (Korean only)

  • University Writing Center

  • Virtual appointments likely still offered; check hours/locations.

  • URL: https://uic.yonsei.ac.kr/writingcenter/default.asp

  • Center for Gender Equity

  • Location: Libertas Hall B, International Campus

  • Tel: 02\text{-}2123\text{-}2137

  • E-mail: helper@yonsei.ac.kr | genderedu@yonsei.ac.kr

Course Policies (Selected Highlights)

• Office Hours

  • “Please attend!” – ask about readings, papers, or philosophical questions.

• Participation & Extensions

  • If sick/extenuating circumstances: notify in advance with official documentation (Health Services, Dean, Athletics).

  • Late notification → course grade may drop 5\%.

• Missed Papers/Exams

  1. Notify before the deadline.

  2. Provide documented excused absence.

  3. Obtain permission for a new due date in advance.

  • Otherwise: automatic 0.

• Academic Integrity

  • Zero tolerance for plagiarism (copying or enabling copying).

  • Penalty may be an “F” for the entire course.

  • Refer to Yonsei UIC Academic Misconduct policy: https://uic.yonsei.ac.kr/main/academic.asp?mid=m030205

• Anti-Discrimination & Harassment

  • Yonsei UIC maintains a harassment-free environment.

  • Sexual harassment is illegal under Title VII (Civil Rights Act 1964) & Title IX (1972).

  • More info: https://uic.yonsei.ac.kr/main/news.asp?mid=m060103&act=view&idx=8146

What Is Critical Reasoning?

• Yonsei UIC catalogue: “Basic skills necessary for logical analysis, normative judgments, and moral reasoning… courses are drawn from logic, epistemology, methodology, and philosophy of science.”

• In plain English: learning how to construct, deconstruct, and evaluate arguments.

Why Study Critical Reasoning?

• Gut instinct & “settled science” are not always enough.

• Quoted rationale (Hurley 2012,\ xiii):

  • Builds skill in constructing & evaluating arguments.

  • Sharpens sensitivity to logical form → clearer communication.

  • Provides defense against prejudice, irrationality, and societal decay.

  • Inconsistency detection distinguishes the rational from the irrational.

• Practical pay-offs

  • Reveals whether personal beliefs are well-grounded or merely biases.

  • Fosters empathy & deeper understanding of opposing views.

  • Equips you to defend controversial positions in academia, workplace, politics.

  • Supplies a fine-grained set of questions for “big questions” (ethics, life-choices, etc.).

Informal Fallacies in Everyday Life (Advertising Examples)

• Slippery Slope

  • Chain of increasingly extreme hypotheticals presented as inevitable.

• Appeal to Authority

  • Endorsement by a non-expert (e.g., actor Daniel Henney advertising coffee) offered as evidence of quality.

• Toolkit outcome: identify, diagnose, & respond to such flawed reasoning.

Arguments: Structure & Evaluation Basics

• Key Formula: Arguments = Premises + Conclusion

  • Premises: claimed evidence/reasons.

  • Conclusion: main claim supported by the premises.

  • Exactly one conclusion; any (finite) number of premises.

• Sample skeleton (formal layout):
  
  \text{P1. All humans are mammals.}\
  \text{P2. Dr. Gregg is a human.}\
  \text{C. Therefore, Dr. Gregg is a mammal.}
  

• Logic = the science of evaluating arguments (good vs. bad).

  • Good: strong, valid, cogent.

  • Bad: weak, invalid, uncogent.

• Course emphasis: HOW the claim is supported, not WHAT the claim is.

  • Example: existence of gravity can be argued well or poorly.

  • Lawyers paid for constructing strong defenses, not merely stating client’s innocence.

Statements & Truth-Value

• Definition: sentence that can be true or false (i.e., has a truth-value).

• True example: “Yonsei UIC’s campus is in Songdo.”

• False example: “The Nile is a river in North America.”

• Non-statements (no truth-value)

  • Questions: “Where is Dr. Pedersen?”

  • Proposals: “Let’s stay awake in class.”

  • Suggestions: “I suggest you watch the road.”

  • Commands: “Turn off your phone!”

  • Exclamations: “Awesome!”

• Controversial cases (normative/moral):

  • “Teachers should get paid more.”

  • “Killing animals for fun is morally bad.”

  • Textbook assumes many “should/ought” sentences CAN be statements; we will follow that.

Indicators: Finding Premises & Conclusions

• Conclusion Indicators (defeasible) \textbf{So}\ ,\ \textbf{therefore}\ ,\ \textbf{thus}\ ,\ \textbf{hence}\ ,\ \textbf{for\ this\ reason}\ ,\ \textbf{it\ follows\ that}\ ,\ \textbf{consequently}\ ,\ \textbf{accordingly}

  • Example: “Titanium… adversely affected… As a result, titanium must be processed in their absence.”

  • Conclusion = processing requirement.

• Premise Indicators \textbf{Since}\ ,\ \textbf{because}\ ,\ \textbf{for}\ ,\ \textbf{in\ that}\ ,\ \textbf{as}\ ,\ \textbf{given\ that}\ ,\ \textbf{may\ be\ inferred\ from}

  • Example: “Since private property helps people define themselves… since it frees people… since it is finite, no individual should accumulate so much property…”

  • Premises = three ‘since’ clauses.

Arguments Without Indicators

• Strategy: ask “What’s the main point?”; that is the conclusion.

• CNN Space-Program passage numbered 1–4:

  • Reconstructed form:
    
    \text{P1. National defense depends on the space program.}\
    \text{P2. The program will pay for itself via spin-offs.}\
    \text{P3. Current funding prevents full potential.}\
    \text{C. Therefore, the space program deserves increased expenditures.}
    

Reconstructing & Labeling Arguments (Notation Tips)

• Premises: P1,\ P2,\ P3,\ \dots

• Conclusion: C

• Standard layout: list premises first, conclusion last.

Practice Examples Discussed in Class

1. CNN WhatsApp excerpt (identify P & C)

   • “Knowing someone has seen a message and isn’t responding… feels like deliberate ignoring… So disabling these tools is a welcome development.”

     • Premise(s): emotional discomfort + social norms.

     • Conclusion: option to disable = welcome.

2. Scientific short passages (Exercise 1.1)

   • Ant “death chemical” (Problem 17)

     • P1: An ant releases a chemical when it dies.

     • P2: Companions then carry it to the compost heap.

     • P3: Healthy ant painted with the chemical is repeatedly dragged away.

     • C: Communication via the chemical is highly effective.

   • Shark respiration (Problem 25)

     • P1: Divers’ tales of “anticipatory” grin are incorrect.

     • P2: Sharks constantly swim with mouths open to avoid suffocation.

     • P3: Continuous water flow over gills supplies oxygen.

     • C: Open-mouth swimming is a respiratory necessity, not anticipation.

3. Quick T/F Review (Exercise 1.1 Part 4)

   • 1: Purpose of premises is to support conclusion – True.

   • 2: Some arguments have multiple conclusions – False.

   • 3: All arguments must have more than one premise – False.

   • 4: “Therefore, hence, so, since, thus” all conclusion indicators – False (note: “since” usually a premise indicator).

   • 5: “For, because, as, for the reason that” all premise indicators – True.

   • 6: Inference ≡ argument – False (related but not identical).

   • 7: In arguments without indicators, conclusion is usually first – Generally True but not guaranteed.

   • 8: Any sentence that is T/F is a statement – True.

   • 9: Every statement has a truth value – True.

Additional Considerations About Statements

• Rule 1: Statements must have a truth-value.

• Rule 2: Having a truth-value ≠ being true; falsity still qualifies.

• Rule 3: Statements can appear standalone or inside arguments (premise/conclusion) or non-arguments (explanations, descriptions).

  • Analogy: \text{NaCl} (sodium chloride) = compound of two independent elements.

• Rule 4: Possible to have arguments & non-arguments composed entirely of false statements.

  • Example: fictional explanation of Mount Doom still an explanation (all false statements).

Ethical, Philosophical & Practical Implications

• Logical literacy combats misinformation, prejudice, and polarized discourse.

• Mastery of argument reconstruction is crucial in law, policy, science communication, and everyday decision-making.

• Attention to premise quality encourages humility: your own stance may weaken or strengthen under scrutiny.

• Accessibility & inclusion (OSD, Writing Center, Gender Equity) reflect ethical commitments intersecting with critical reasoning: ensure all voices can engage in rational discourse.