Logical Structure of Arguments

1. Logical Structure of Arguments Mary Jean Harrold

2. Overview • Real-world argument not formal logic • Difference between formal logic and real-world argument • Real-world argument • grounded in beliefs, assumptions, or values granted by the audience • these beliefs, assumptions, and values often unstated Mary Jean Harrold

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

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

5. Overview • Consider argument “Rabbits make good pets because they are gentle” • What is underlying assumption of this argument? • What is an enthymeme? • 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

6. 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 Mary Jean Harrold

7. 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

8. 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

9. 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 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

10. 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

11. 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

12. 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

13. 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

14. 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

15. Audience-based Reasons Mary Jean Harrold

16. ISSUE QUESTION: Should it be legal for drivers to talk on cell phones while driving? Audience: Your state political representatives Claim: Cell phones should be illegal to use while driving. Reason 1: because holding a cell phone in one hand diminishes drivers’ capacity to control their cars physically Grounds: Find statistics showing how many drivers have had trouble making turns or staying in their lanes when talking on ca cell phone; statistics of number of accidents caused by cell phone users Warrant: Anything that interferes with drivers’ ability to handle their cars is bad Backing: Conditions of Rebuttal for Reason 1: Cell phones have been shown to be valuable in road emergencies; many business people need cell phones to make contact with clients and need to save time by talking while they are driving; drivers use their hands to do a lot of other equally or more distracting things while driving, such as drinking coffee, reading, fiddling with CDs and tapes, shaving, putting on make-up; should these activities be banned too? Qualifier: Except with a headset of speaker-phone, cell phones should be illegal to use while driving Mary Jean Harrold

17. ISSUE QUESTION: Should it be legal for drivers to talk on cell phones while driving? Audience: Your state political representatives Claim: Cell phones should be illegal to use while driving. Reason 2: Grounds: Warrant: Backing: Conditions of Rebuttal for Reason 2 Qualifier: Mary Jean Harrold

18. 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

19. 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

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

21. 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