Unit 2: Argument Analysis
Arguments are the fundamental components of all rational discourse: nearly everything we read and write, like scientific reports, newspaper columns, and personal letters, as well as most of our verbal conversations contain arguments. Picking the arguments out from the rest of our often convoluted discourse can be difficult. 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 that we can use to determine whether they are good or bad.
In this unit, you 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.
Completing this unit should take you approximately 7 hours.
Upon successful completion of this unit, you will be able to:
- construct valid and sound arguments using the standard form of an argument;
- determine if a counterexample exists for a given argument;
- illustrate valid argument patterns such as modus ponens, modus tollens, hypothetical syllogism, disjunctive syllogism, constructive dilemma, and reductio ad absurdum;
- identify hidden and implicit assumptions in an argument;
- explain the differences between deductive reasoning and inductive reasoning;
- explain the pattern of inductive reasoning called an analogical argument;
- construct an argument map for an argument; and
- apply the criteria for evaluating the strength of an argument to any given argument.
- construct valid and sound arguments using the standard form of an argument;
2.1: The Nature of Arguments
2.1.1: What Are Arguments?
Read section 1.1 (p. 1-3) of this textbook, which differentiates an argument in the logical sense from the ordinary language sense of a heated disagreement, and introduces you to the basic structures of logical argument: statements, premises, and conclusions.
Complete Exercise 1 at the end of the subsection, identifying which sentences are statements, and once you identify them, begin thinking about what premises might lead to those statements. When you finish, check your responses with the answer key on p. 207.
The entire text book can be found here: Introduction to Logic and Critical Thinking
Read this tutorial, which explains how to identify and argument by picking out its components. Complete the exercises and check your answers.
2.1.2: How to Tell an Argument from a Non-Argument
Read section 1.2 (p. 4-7) of this textbook, which will give you some tips for how to spot an argument. While the premise indicators and conclusion indicators are not guarantees of an argument, they can assist you to identify an argument.
Complete Exercise 2, at the end, distinguishing arguments from non-arguments and identifying the conclusion of argument sentences. Despite the name, the conclusion often precedes the premises when we present arguments in ordinary language. When you finish the exercise, check your answers against the answer key on p. 207.
The entire text book can be found here: Introduction to Logic and Critical Thinking
Read this tutorial, which explains how to put an argument in standard form, and complete the exercise.
2.2: Good Argument Form
Section 1.6 (p. 17-23) will introduce you to the concept of validity – the term for when the conclusion of an argument follows from its premises. Pay careful attention to the difference between validity and soundness, the concept introduced in section 1.7. All sound arguments are valid, but not all valid arguments are sound. Remember that premises do not have to be true for an argument to be valid.
Complete Exercise 5, checking your answers against the key on pages 209-210.
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, starting with A03 and clicking through to A05, 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 and check your answers.
Complete this true/false knowledge check, 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.
Read sections 1.8 through 1.10 (p. 23-36) to learn how to round out arguments, conceptually. Section 1.8 will distinguish between two types of argument: deductive, and inductive. Pay careful attention to the difference between these two, and think about which kind of argument you use more often. Section 1.9 will help you identify arguments with a missing premise and determine how and when to supply this missing premise. It will also introduce you to the principle of charity and the difference between normative and descriptive statements – three very important terms! Section 1.10 shows you three rhetorical devices to hint at further argument without actually going through the argument: assuring, guarding and discounting.
Complete Exercises 6 and 7, checking your answers against the keys on pages 210-211.
- When arguments are stated verbally or in writing, their structure may not be completely explicit. "Hidden Assumptions" provides clues about how to identify hidden assumptions. "Inductive Reasoning" 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. "Good Arguments" puts together a number of the ideas laid out so far in order to describe the characteristics of a good argument.Complete the exercises and check your answer.
2.3: Visualizing How Arguments Work
Visualizing argument structure can be helpful for determining how directly or indirectly supporting evidence leads to a conclusion. Section 1.4, on pages 10-15, gives examples of simple arguments and more complex arguments using arrows to represent the structure of an argument.
Complete Exercise 4 on pages 14-15. A key for writing the arguments in standard form is on pages 208-209 but there is no key for diagramming.
Read this tutorial about how to construct an argument map. Argument maps are a way of visually representing the logical structure of an argument.
2.4: Analogical Arguments
Read section 3.3 (p. 154-158) about a sort of inductive argument many people use quite frequently: arguments from analogy. As you read, think about the difference between relevant and irrelevant similarities when it comes to analogies, as well as relevant disanalogies. Being able to identify these will help you make stronger inductive arguments.
Complete Exercise 24 and check against the answer key on pages 230-231.
Read this tutorial on analogical arguments. Arguments that are based on analogies have certain inherent weaknesses. This tutorial will help you find out how analogical arguments are structured as well as the most common ways in which they may be undermined.
2.5: Valid Argument Patterns
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).
2.6: Review of Argument Analysis
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
Share your thoughts on the discussion forum by clicking on the link above and creating a free account, if you have not already done so. 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.