# PHIL102: Logic and Critical Thinking

Unit 2: Argument Analysis   Arguments are the fundamental components of all rational discourse.  Nearly everything we read and write—scientific reports, newspaper columns, personal letters, and most of our verbal conversations as well—contains arguments.  Picking them out from the rest of our (often messy) discourse can be difficult though.  Once we have identified an argument, we still need to determine whether or not it is sound.  Luckily, arguments obey a set of formal rules, which we can use to determine whether they are good or bad.  In this unit, we will learn how to identify arguments, what makes an argument sound (as opposed to unsound or merely valid), the difference between deductive and inductive reasoning, and how to map arguments to reveal their structure.

This unit should take you approximately 11 hours. ☐    Subunit 2.1: 2 hours

☐    Subunit 2.2: 5.5 hours

☐    Subunit 2.2.1: 3 hours

☐    Subunit 2.2.2: 2.5 hours

☐    Subunit 2.3: 1 hour

☐    Subunit 2.4: 1 hour

☐    Subunit 2.5: 1 hour

☐    Subunit 2.6: 0.5 hours

Unit2 Learning Outcomes
Upon successful completion of this unit, you will be able to: - define and illustrate the notion of an argument; - identify arguments in passages of text; - define the notion of standard form for an argument; - identify arguments that are in standard form; - define the notions of validity and soundness; - identify whether an argument is valid or sound; - define and illustrate the notion of a counterexample; - determine whether there is a counterexample to an argument; - illustrate several valid argument patterns: modus ponens, modus tollens, hypothetical syllogism, disjunctive syllogism, dilemma, and reductio ad absurdum; - define and illustrate the notion of a hidden or implicit assumption; - identify hidden assumptions in an argument; - describe and illustrate the differences between deductive reasoning and inductive reasoning; - identify criteria for a good argument, and apply those criteria to determine whether an argument is good; - construct and identify an argument map for an argument; - define the notion of an analogical argument – or argument by analogy; - contrast analogical arguments with inductive arguments; and - identify and apply the criteria for evaluating the strength of an analogical argument.

2.1 The Nature of Arguments   2.1.1 What Arguments Are   - Lecture: iTunes U: University of Oxford: Professor Marianne Talbot’s Critical Reasoning for Beginners: “The Nature of Arguments” Link: iTunes U: University of Oxford: Professor Marianne Talbot’s Critical Reasoning for Beginners: “The Nature of Arguments” (iTunes U)

Instructions: Watch this conversational video lecture, which introduces the concept of an argument.

Watching this video lecture and pausing to take notes should take approximately 1 hour.

2.1.2 How to Tell an Argument from a Non-Argument   - Reading: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorials A01 and A02” Link: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorials A01 and A02” (HTML)

Instructions: Read these two tutorials, which explain how to identify an argument by picking out its components and how to put an argument in standard form. Be sure to follow any hyperlinks included in the readings.

Complete the exercises for each tutorial. Then, check your answers against the “Tutorial A01 Answer Key” (PDF) and “Tutorial A02 Answer Key” (PDF).

Reading these tutorials and completing the exercises should take approximately 1 hour.

2.2 Good Argument Form   2.2.1 Validity and Soundness   - Reading: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorials A03–A05” Link: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis:“Tutorials A03–A05” (HTML)

Instructions: Validity and soundness are two of the most important concepts in the study of arguments, and they are often confused with one another. Read these three tutorials on the distinction between valid and sound arguments, their relationship to the truth of the statements that make them up, and the structural patterns that help us to recognize them.

Complete the exercises for each tutorial. Then, check your answers against the following: “Tutorial A03 Answer Key” (PDF),“Tutorial A04 Answer Key” (PDF), and “Tutorial A05 Answer Key” (PDF).

Reading these tutorials and completing the exercises should take approximately 2 hours and 30 minutes.

• Assessment: Lander University: Lee C. Archie’s “Introduction to Logic Quiz: Truth, Validity, and Soundness” Link: Lander University: Lee C. Archie’s “Introduction to Logic Quiz: Truth, Validity, and Soundness” (PDF)

Also available in:
HTML

Instructions: Complete this true/false quiz, which tests your knowledge of the distinction between valid and sound arguments. Note that deductive arguments might be, but need not be, valid or sound; deductive arguments may be valid or invalid, and they may be sound or unsound.

If you use the HTML version, a pop-up window will open indicating whether you got the answer correct or not, as well as an explanation why. You may also check your answers against the “Quiz: Truth, Validity and Soundness Answer Key” (PDF).

Completing this assessment should take approximately 30 minutes.

2.2.2 More about Good Argument Form   - Reading: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorials A06–A08” Link: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorials A06–A08” (HTML)

Instructions: Read these three tutorials. When arguments are stated verbally or in writing, their structure may not be completely explicit. Tutorial 06 provides clues about how to identify hidden assumptions. Tutorial 07 introduces the important concept of induction. Inductive arguments form a whole second class of arguments, alongside deductive ones, and will be important in our unit on scientific reasoning later on. Tutorial 08 puts together a number of the ideas laid out so far in order to describe the characteristics of a good argument.

Complete the exercises for Tutorial A06 and Tutorial A08. Then, check your answers against the “Tutorial A06 Answer Key” (PDF) and “Tutorial A08 Answer Key” (PDF).

Reading these tutorials and completing the exercises should take approximately 1 hour and 30 minutes.

• Lecture: iTunes U: University of Oxford: Marianne Talbot’s Critical Reasoning for Beginners: “Different Types of Arguments” Link: iTunes U: University of Oxford: Marianne Talbot’s Critical Reasoning for Beginners: “Different Types of Arguments” (iTunes U)

Instructions: Watch this video lecture, which is about the difference between deductive and inductive arguments.

Watching this video lecture and pausing to take notes should take approximately 1 hour.

2.3 Visualizing How Arguments Work   - Reading: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorial A09” Link: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorial A09” (HTML)

`````` Instructions: Read this tutorial about how to construct an argument
map. Argument maps are a way of visually representing the logical
structure of an argument.

(PDF).

Reading this tutorial and completing the exercises should take
approximately 1 hour.

attributed to Joe Lau and Jonathan Chan, and the original version
can be found [here](http://philosophy.hku.hk/think/).
``````

2.4 Analogical Arguments   - Reading: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorial A10” Link: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorial A10” (HTML)

`````` Instructions: Read this tutorial on analogical arguments. Arguments
that are based on analogies have certain inherent weaknesses. This
structured as well as the most common ways in which they may be
undermined.

(PDF).

Reading this tutorial and completing the exercises should take
approximately 1 hour.

attributed to Joe Lau and Jonathan Chan, and the original version
can be found [here](http://philosophy.hku.hk/think/).
``````

2.5 Valid Argument Patterns   - Reading: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorial A11” Link: University of Hong Kong’s Critical Thinking Web: Joe Lau and Jonathan Chan’s Argument Analysis: “Tutorial A11” (HTML)

`````` Instructions: Read this tutorial on how to reduce valid arguments
to their basic structure through the use of argument patterns.

This reading provides a preview of the kind of analysis we will be
doing a lot more of in unit 4. This kind of strategy is sometimes
useful with analyzing arguments in real-life situations. For
example, you might see these types of questions and find identifying
argument patterns useful for the Law School Admission Test (LSAT).

Reading this tutorial should take approximately 1 hour.

attributed to Joe Lau and Jonathan Chan, and the original version
can be found [here](http://philosophy.hku.hk/think/).
``````

2.6 Review of Argument Analysis   - Activity: The Saylor Foundation’s “PHIL102 Discussion Forum” Link: The Saylor Foundation’s “PHIL102 Discussion Forum” (HTML)

Instructions: Try to formulate examples for three important patterns of argument: modus ponens, modus tollens, and reductio. Then, for the following argument sent to a newspaper by a reader responding to an article claiming that Shakespeare was Italian, identify the argument’s main conclusion and spell out the argument’s premises.

“So Shakespeare was an Italian, because almost half of his plays are set in Italy. Almost all of Isaac Asimov’s novels are set in outer space—does that mean he was a Martian?” – Graham Simpson, Cairns, Qld

`````` Share your thoughts on the discussion forum by clicking on the link
Read arguments that other students may have constructed, as well as
their attempts to analyze the Shakespeare argument. Respond to at
least one or two other students’ posts.

Completing this activity should take approximately 30 minutes.