Logical Structure of Arguments

Logical Structure of Arguments Mary Jean Harrold

Argument Core of an argument • Logos—internal consistency, logical, best reasons, supporting evidence • Pathos—make reader open to message, appeal to their values, engage them emotionally • Ethos—enhance my credibility, present myself effectively Mary Jean Harrold

Quick Quiz Name 1. Write three questions that would be appropriate from today’s reading assignment: Writing Arguments, Chapter 5 2. Answer these questions Mary Jean Harrold

Overview • Real-world argument not formal logic • Differences between formal logic and real-world argument Mary Jean Harrold

Overview • What are examples of arguments in which beliefs, assumptions, and values are shared by audience and can remain unstated? Mary Jean Harrold

Overview • What is an enthymeme? Mary Jean Harrold

Overview • Consider argument “<complete> ” • What is underlying assumption of this argument? • Complete it by stating unstated assumption • Initial enthymeme: • Claim: • Stated reason: • Unstated reason: Mary Jean Harrold

Overview • Consider argument “Rabbits make good pets because they are gentle” • What is underlying assumption of this argument? • Complete it by stating unstated assumption • Initial enthymeme: “Rabbits make …gentle” • Claim: “Rabbits make good pets” • Stated reason: “Because they are gentle” • Unstated reason: “Gentle animals make good pets.” Mary Jean Harrold

Overview • Consider argument “Practicing piano is good for kids because it teaches good discipline” • What is underlying assumption of this argument? • Complete it by stating unstated assumption • Initial enthymeme: • Claim: • Stated reason: • Unstated reason: Mary Jean Harrold

Overview What car should we buy? • We should buy a Geo Metro because it is extremely economical. • We should buy a used Volvo because it is very safe. • We should buy this Ford Escort because it is red. How would we support these arguments? Mary Jean Harrold

The Toulmin System Enthymeme An incomplete logical structure Toulmin’s model • All assertions and assumptions are contestable by “opposing counsel” • All final “verdicts” about the persuasiveness of alternative arguments will be rendered by a neutral third party, a judge or jury. Implications of Toulmin’s model for argument • Must anticipate counter arguments and question assumptions • Must be fair in representing the other side • Must make sure our argument is not constructed just for those who already agree with us Mary Jean Harrold

The Toulmin System (cont’d) Example Initial enthymeme: We should buy this used Volvo because it is extremely safe Claim: We should buy this used Volvo Stated Reason: because it is is extremely safe Unstated Reason: because we should buy the car that is the safest In Toulmin’s system, the unstated reasons are warrants Warrant: The safest car is the best car Mary Jean Harrold

The Toulmin System (cont’d) Example Initial enthymeme: We should buy this used Volvo because it is extremely safe Claim: We should buy this used Volvo Stated Reason: It is extremely safe Warrant: The safest car is the best car How do we support the reason and warrant? Mary Jean Harrold

The Toulmin System (cont’d) Example Initial enthymeme: We should buy this used Volvo because it is extremely safe Claim: We should buy this used Volvo Stated Reason: It is extremely safe Warrant: The safest car is the best car How do we support the reason and warrant? Support stated reason with grounds (evidence, what you have to go on---facts, statistics, data, testimony, interviews, surveys, …) Support warrant with backing (for audience who may not share the unstated claim, why do you believe this, how do you know this…) Mary Jean Harrold

The Toulmin System (cont’d) Example Initial enthymeme: We should buy this used Volvo because it is extremely safe Claim: We should buy this used Volvo Stated Reason: It is extremely safe Grounds: Warrant: The safest car is the best car Backing: Mary Jean Harrold

The Toulmin System (cont’d) Example Initial enthymeme: We should buy this used Volvo because it is extremely safe Claim: We should buy this used Volvo Stated Reason: It is extremely safe Grounds: Warrant: The safest car is the best car Backing: How do we address the resistant audience Conditions of Rebuttal: • Rebutting reasons and grounds • Rebutting the warrant and backing Qualifier since cannot usually prove your argument, qualify it Mary Jean Harrold

Exercise Use Toulmin’s scheme to help determine what you have to consider in developing the following enthymeme Practicing Piano is good for kids because it teaches discipline Mary Jean Harrold

Audience-based Reasons • Audience-based VS writer-based • Discussion: • What is the warrant • Will audience grant it? • Audience: a beleaguered parent • I should be allowed to stay out until 2 A.M. because all my friends do • I should be allowed to stay out until 2 A.M. because only if I’m free to make my own decisions will I mature Mary Jean Harrold

Who is Your Audience • Who is your audience? • How much do they care about your issue? • What is your audience’s current attitude toward your issue? • What will be your audience’s likely objections to your argument? • What values, beliefs, or assumptions about the work do you and your audience share? Mary Jean Harrold

What Will Be Your Audiences in the Next Five Years? In each case, for what are you trying to argue? Mary Jean Harrold

What Will Be Your Audiences in the Next Five Years? In each case, for what are you trying to argue? • A company where you want to get a job • A boss whom you want to convince about your project. • A project leader whom you want to convince about your design. • A customer whom you want to convince about your plan for developing their software. • A graduate school where you want to enroll. • A teacher whom you want to convince to pass you Mary Jean Harrold

Logical Structure of Arguments