Logic: American Association of State Colleges and Universities and Subsequent Rights Restrictions

Sequenced. Precise. Elegant. Clear. Hurley’s A Concise Introduction to Logic, 11th Edition How to Make an Origami Crane Make your own origami crane using these instructions and the perforated sheet of paper included in your book. 1. Start with a square piece of paper, colored side up. Fold in half and open. Then fold in half the other way. 2. Turn the paper over to the white side. Fold the paper in half, crease well and open, and then fold again in the other direction. 3. Using the creases you have made, bring the top 3 corners of the model down to the bottom corner.Flatten model. The iconic red crane on the cover of this new edition of Hurley’s, A Concise Introduction to Logic symbolizes the qualities that make it the most successful logic text on the market. We have chosen origami to symbolize this text’s careful sequencing, precision, elegance, and clarity. About the Cover 4. Fold top triangular flaps into the center and unfold. 5. Fold top of model downwards, crease well and unfold. 6. Open the uppermost flap of the model, bringing it upwards and pressing the sides of the model inwards at the same time. Flatten down, creasing well.Couple an icon steeped in tradition with a clean, modern design, and you will quickly get a sense of the qualities that make this new edition of Hurley the best yet. Along with instructions, each new text includes a sheet of red paper so that you can bring the cover to life. This exercise serves as a metaphor for the process of learning logic. It is challenging, requires practice, but can be fun. Ideas for other ways to create your own origami can be found at www. origami-resource-center. com. 7. Turn model over and repeat Steps 4-6 on the other side. . Fold top flaps into the center. 9. Repeat on other side. 10. Fold both ‘legs’ of 11. Inside Reverse Fold the â€Å"legs† model up, crease along the creases very well, then you just made. unfold. Finished Crane. 12. Inside Reverse Fold one si de to make a head, then fold down the wings. Source: www. origami-fun. com Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. A C O N C I S E I N T R O D U C T I O N TO Logic Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience.Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. A C O N C I S E I N T R O D U C T I O N TO Logic ELEVENTH EDITION PATRICK J. HURLEY University of San Diego Australia †¢ Brazil †¢ Japan †¢ Korea †¢ Mexico †¢ Singapore †¢ Spain †¢ United Kingdom †¢ United States Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. This is an electronic version of the print textbook. Due to electronic rights restrictions, some third party content may be suppressed. Editorial review has deemed that any suppressed content does not materially affect the overall learning experience.The publisher reserves the right to remove content from this title at any time if subsequent rights restrictions require it. For valuable information on pricing, previous editions, changes to current editions, and alternate formats, please visit www. cengage. com/highered to search by ISBN#, author, title, or keyword for materials in your areas of interest. Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party co ntent may be suppressed from the eBook and/or eChapter(s).Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. A Concise Introduction to Logic, Eleventh Edition Patrick J. Hurley Publisher: Clark Baxter Senior Sponsoring Editor: Joann Kozyrev Development Editor: Florence Kilgo Assistant Editor: Nathan Gamache Editorial Assistant: Michaela Henry Media Editor: Diane Akerman Marketing Manager: Mark T.Haynes Marketing Coordinator: Josh Hendrick Marketing Communications Manager: Laura Localio Content Project Manager: Alison Eigel Zade Senior Art Director: Jennifer Wahi Print Buyer: Paula Vang Production Service: Elm Street Publishing Services Internal designer: Yvo Riezebos Cover designer: Jeff Bane of CMB Design Partners Cover image: Courtesy of Getty Images: Red origami crane on white table (image numbe r 85592979) Compositor: Integra Software Services Pvt. Ltd.  © 2012, 2008, 2006 Wadsworth, Cengage Learning ALL RIGHTS RESERVED.No part of this work covered by the copyright herein may be reproduced, transmitted, stored, or used in any form or by any means graphic, electronic, or mechanical, including but not limited to photocopying, recording, scanning, digitizing, taping, Web distribution, information networks, or information storage and retrieval systems, except as permitted under Section 107 or 108 of the 1976 United States Copyright Act, without the prior written permission of the publisher.For product information and technology assistance, contact us at Cengage Learning Customer & Sales Support, 1-800-354-9706 For permission to use material from this text or product, submit all requests online at www. cengage. com/permissions. Further permissions questions can be emailed to [email  protected] com. Library of Congress Control Number: 2010924757 Student Edition: ISBN-13: 978 -0-8400-3417-5 ISBN-10: 0-8400-3417-2 Wadsworth 20 Channel Center Street Boston, MA 02210 USA Cengage Learning is a leading provider of customized learning solutions with o? e locations around the globe, including Singapore, the United Kingdom, Australia, Mexico, Brazil, and Japan. Locate your local o? ce at: international. cengage. com/region Cengage Learning products are represented in Canada by Nelson Education, Ltd. For your course and learning solutions, visit www. cengage. com. Purchase any of our products at your local college store or at our preferred online store www. cengagebrain. com. Printed in the United States of America 1 2 3 4 5 6 7 14 13 12 11 10 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. To: All of the instructors, past and present, who have taught logic from this book. It is wrong always, everywhere, and for anyone, to believe anything upon insufficient evidence. –W. K. Clifford Nothing can be more important than the art of formal reasoning according to true logic. Gottfried Wilhelm Leibniz Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Brief Contents Preface xiii PART I  Ã‚  INFORMAL LOGIC 1 2 3 Basic Concepts 1 Lang uage: Meaning and De? ition 78 Informal Fallacies 119 PART II  Ã‚  FORMAL LOGIC 4 5 6 7 8 Categorical Propositions 197 Categorical Syllogisms 259 Propositional Logic 310 Natural Deduction in Propositional Logic 380 Predicate Logic 442 PART III  Ã‚  INDUCTIVE LOGIC 9 10 11 12 13 14 Analogy and Legal and Moral Reasoning 509 Causality and Mill’s Methods 529 Probability 554 Statistical Reasoning 571 Hypothetical/Scienti? c Reasoning 593 Science and Superstition 615 Appendix: Logic and Graduate-Level Admissions Tests 644 Answers to Selected Exercises 655 Glossary/Index 697 vi Copyright 2010 Cengage Learning. All Rights Reserved.May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Contents Preface xiii PART I? INFORMAL LOGIC 1 Basic Concepts EXERCISE 1. 1 7 1 1 14 33 1. 1 Arguments, Premises, and Conclusions 1. 2 Recognizing Arguments EXERCISE 1. 2 25 1. 3 Deduction and Induction EXERCISE 1. 40 1. 4 Validity, Truth, Soundness, Strength, Cogency 44 EXERCISE 1. 4 53 1. 5 Argument Forms: Proving Invalidity EXERCISE 1. 5 63 57 1. 6 Extended Arguments EXERCISE 1. 6 70 64 2 Language: Meaning and De? nition 2. 1 Varieties of Meaning EXERCISE 2. 1 83 78 78 88 2. 2 The Intension and Extension of Terms EXERCISE 2. 2 92 2. 3 De? nitions and Their Purposes EXERCISE 2. 3 99 93 2. 4 De? nitional Techniques EXERCISE 2. 4 108 102 111 2. 5 Criteria for Lexical De? nitions EXERCISE 2. 5 115 vii Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial revi ew has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 3 Informal Fallacies 3. 1 Fallacies in General EXERCISE 3. 1 121 119 122 138 119 3. 2 Fallacies of Relevance EXERCISE 3. 2 133 3. 3 Fallacies of Weak Induction EXERCISE 3. 3 149 3. 4 Fallacies of Presumption, Ambiguity, and Grammatical Analogy 156 EXERCISE 3. 4 170 . 5 Fallacies in Ordinary Language EXERCISE 3. 5 185 178 PART II? FORMAL LOGIC 4 Categorical Propositions 197 4. 1 The Components of Categorical Propositions 197 EXERCISE 4. 1 200 4. 2 Quality, Quantity, and Distribution EXERCISE 4. 2 204 200 4. 3 Venn Diagrams and the Modern Square of Opposition 205 EXERCISE 4. 3 216 4. 4 Conversion, Obversion, and Contraposition EXERCISE 4. 4 225 217 4. 5 The Traditional Square of Opposition EXERCISE 4. 5 234 227 4. 6 Venn Diagrams and the Traditional Standpoint 239 EXERCISE 4. 6 245 4. 7 Translating Ordinary Language Statements into Categorical Form 246 EXERCISE 4. 254 viii Contents Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 5 Categorical Syllogisms 259 5. 1 Standard Form, Mood, and Figure 259 EXERCISE 5. 1 264 5. 2 Venn Diagrams EXERCISE 5. 277 266 280 288 292 5. 3 Rules and Fallacies EXERCISE 5. 3 286 5. 4 Reducing the Number of Terms EXERCISE 5. 4 291 5. 5 Ordinary Language Arguments EXERCISE 5. 5 294 5. 6 Enthymemes 295 EXERCISE 5. 6 297 5. 7 Sorites 301 EXERCISE 5. 7 304 6 Propositional Logic EXERCISE 6. 1 319 310 6. 1 Symbols and Translation 310 6. 2 Truth Functions EXERCISE 6. 2 332 323 6. 3 Truth Tables for Propositions 335 EXERCISE 6. 3 341 6. 4 Truth Tables for Arguments EXERCISE 6. 4 347 344 6. 5 Indirect Truth Tables 350 EXERCISE 6. 5 358 6. 6 Argument Forms and Fallacies EXERCISE 6. 6 371 360 Contents ixCopyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 7 Natural Deduction in Propositional Logic 380 7. 1 Rules of Implication I 380 EXERCISE 7. 1 386 7. 2 Rules of Implication II 391 EXERCISE 7. 396 7. 3 Rules of Replacement I 401 EXERCISE 7. 3 407 7. 4 Rules of Replacement II EXERCISE 7. 4 419 414 7. 5 Conditional Proof EXERCISE 7. 5 430 427 7. 6 Indirect Proof EXERCISE 7. 6 436 432 438 7. 7 Proving Logical Truths EXERCISE 7. 7 440 8 Predicate Logic 442 8. 1 Symbols and Translation 442 EXERCISE 8. 1 449 8. 2 Using the Rules of Inference EXERCISE 8. 2 460 451 8. 3 Change of Quanti? er Rule EXERCISE 8. 3 467 464 468 8. 4 Conditional and Indirect Proof EXERCISE 8. 4 472 8. 5 Proving Invalidity EXERCISE 8. 5 479 474 481 8. 6 Relational Predicates and Overlapping Quanti? ers EXERCISE 8. 6 489 . 7 Identity 492 EXERCISE 8. 7 501 x Contents Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions r equire it. Part III INDUCTIVE LOGIC 9 Analogy and Legal and Moral Reasoning 509 9. 1 Analogical Reasoning 9. Legal Reasoning 9. 3 Moral Reasoning EXERCISE 9 520 509 512 516 10 Causality and Mill’s Methods 10. 2 Mill’s Five Methods 531 10. 3 Mill’s Methods and Science EXERCISE 10 546 529 529 10. 1 â€Å"Cause† and Necessary and Sufficient Conditions 540 11 Probability 554 11. 1 Theories of Probability 11. 2 The Probability Calculus EXERCISE 11 567 554 557 12 Statistical Reasoning 571 12. 1 Evaluating Statistics 571 12. 2 Samples 572 576 12. 3 The Meaning of â€Å"Average† 12. 4 Dispersion 578 12. 5 Graphs and Pictograms 12. 6 Percentages 586 EXERCISE 12 588 583 13 Hypothetical/Scienti? c Reasoning 593 13. The Hypothetical Method 593 13. 2 Hypothetical Reasoning: Four Examples from Science 596 Contents xi Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, som e third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 13. 3 The Proof of Hypotheses EXERCISE 13 607 02 13. 4 The Tentative Acceptance of Hypotheses 604 14 Science and Superstition 14. 2 Evidentiary Support 14. 3 Objectivity 14. 4 Integrity EXERCISE 14 615 615 14. 1 Distinguishing Between Science and Superstition 616 621 625 630 631 14. 5 Concluding Remarks Appendix: Logic and Graduate-Level Admissions Tests 644 Answers to Selected Exercises Glossary/Index 697 655 xii Contents Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).Editorial review has deemed that an y suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Preface The most immediate benefit derived from the study of logic is the skill needed to construct sound arguments of one’s own and to evaluate the arguments of others. In accomplishing this goal, logic instills a sensitivity for the formal component in language, a thorough command of which is indispensable to clear, e? ective, and meaningful communication.On a broader scale, by focusing attention on the requirement for reasons or evidence to support our views, logic provides a fundamental defense against the prejudiced and uncivilized attitudes that threaten the foundations of our democratic society. Finally, through its attention to inconsistency as a fatal ? aw in any theory or point of view, logic proves a useful device in disclosing ill-conceived policies in the politic al sphere and, ultimately, in distinguishing the rational from the irrational, the sane from the insane. This book is written with the aim of securing these bene? s. Every Book Has a Story When I ? rst began teaching introductory logic many years ago, I selected a textbook that was widely used and highly regarded. Yet, my students often had a hard time understanding it. The book tended to be overly wordy and the main points were often lost amid a welter of detail. Also, I found that much of the book’s content was only peripherally related to the central concepts of logic. Using this book provided the happy and unanticipated result that my students always came to class so they could hear me explain the textbook.But after I tired of doing this, I decided to write a textbook of my own that would address the de? ciencies of the one I had been using. Speci? cally, my goal was to write a book in which the main points were always presented up front so students could not possibly mis s them, the prose was clear and uncomplicated, and excess verbiage and peripheral subject matter was avoided. To accomplish these and other related goals, I incorporated the following pedagogical devices: †¢ Relevant and up-to-date examples were used extensively throughout the book. †¢ Key terms were introduced in bold face type and de? ed in the glossary/index. †¢ Central concepts were illustrated in graphic boxes. †¢ Numerous exercises—today there are over 2,600—were included to perfect student skills. †¢ Many exercises were drawn from real-life sources such as textbooks, newspapers, and magazines. †¢ Typically every third exercise was answered in the back of the book so students could check their work. xiii Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).Editorial re view has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. †¢ Chapters were organized so that earlier sections provided the foundation for later ones. Later sections could be skipped by instructors opting to do so. †¢ Important rules and tables were printed on the inside covers for ready access. In its ? rst edition, the book was so well received that plans were quickly begun for a second edition.With the completion of that and later editions, the book grew to incorporate many new features: †¢ Venn diagrams for syllogisms were presented in a novel and more e? ective way using color to identify the relevant areas. †¢ Dialogue exercises were included to depict the commission of fallacies in real life. †¢ Predicate logic was extended to include relational predicates and identity. †¢ The Emin ent Logicians feature was introduced to enhance the human element: it presented the lives of historically prominent logicians. †¢ â€Å"Truth Trees† and â€Å"Critical Thinking and Writing† were written as supplements. Learning Logic, a multimedia program that includes an additional 2,000 exercises and that practically teaches the course by itself, was included in the package. †¢ A series of videos dealing with topics that students ? nd di? cult, including the concept of validity, indirect truth tables, and natural deduction, were o? ered with the last edition. I am convinced that with each successive edition the book has become a more e? ective teaching tool. I am also convinced that the current, eleventh edition, is the best and most accurate one to date. New To This Edition †¢ Five new biographical vignettes of prominent logicians are introduced.The new logicians include Ruth Barcan Marcus, Alice Ambrose, Ada Byron (Countess of Lovelace), Willard Van Orman Quine, and Saul Kripke. †¢ Six new dialogue exercises are introduced to help a? rm the relevance of formal logic to real-life. They can be found in Sections 5. 6, 6. 4, 6. 6, 7. 3, 7. 4, and 8. 2. †¢ The end-of-chapter summaries now appear in bullet format to make them more useful for student review. †¢ Many new and improved exercises and examples appear throughout the book. †¢ In Section 1. 4, the link between inductive reasoning and the principle of the uniformity of nature is explained.Cogent inductive arguments are those that accord with this principle, while weak ones violate it. Such violations are always accompanied by an element of surprise. xiv Preface Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially aff ect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. The connection between the Boolean Standpoint and the Aristotelian standpoint is explained more completely. †¢ The existential fallacy as it occurs in immediate inferences is explained in greater detail. All inferences that commit this fallacy have a universal premise and a particular conclusion. The meaning of â€Å"universal† and â€Å"particular† are extended to cover statements that are given as false. †¢ A new exercise set is introduced in Section 4. 5 that involves testing immediate inferences for soundness. †¢ An improved de? nition of the â€Å"main operator† of a compound statement is given. A new subsection is introduced in Section 6. 5 giving preliminary instruction on how to work backward from the truth values of the simple propositions to the truth values of the operators. A ne w exercise set provides practice with this technique. †¢ Section 7. 1 has been rewritten, emphasizing the strategy of trying to â€Å"? nd† the conclusion in the premises. †¢ Margin of error in Chapter 12 is now explained in terms of level of expectation. A more informative table illustrates this change. A complete list of all improvements is given at the beginning of the Instructor’s Manual.Note to the Student Imagine that you are interviewing for a job. The person across the desk asks about your strengths, and you reply that you are energetic, enthusiastic, and willing to work long hours. Also, you are creative and innovative, and you have good leadership skills. Then the interviewer asks about your weaknesses. You hadn’t anticipated this question, but after a moment’s thought you reply that your reasoning skills have never been very good. The interviewer quickly responds that this weakness could create big problems. â€Å"Why is that? † you ask. Because reasoning skills are essential to good judgment. And without good judgment your creativity will lead to projects that make no sense. Your leadership skills will direct our other employees in circles. Your enthusiasm will undermine everything we have accomplished up until now. And your working long hours will make things even worse. † â€Å"But don’t you think there is some position in your company that is right for me? † you ask. The interviewer thinks for a moment and then replies, â€Å"We have a competitor on the other side of town. I hear they are hiring right now. Why don’t you apply with them? †The point of this little dialogue is that good reasoning skills are essential to doing anything right. The business person uses reasoning skills in writing a report or preparing a presentation; the scientist uses them in designing an experiment or clinical trial, the department manager uses them in maximizing worker e? ciency, the law yer uses them in composing an argument to a judge or jury. And that’s where logic comes in. The chief purpose of logic is to develop good reasoning skills. In fact, logic is so important that when the liberal arts program of studies was formulated ? fteen hundred years Preface v Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. ago, logic was selected as one of the original seven liberal arts. Logic remains to this day a central component of a college or university education.From a more pragmatic angle, logic is important to earning a good score on any of the several tests required for admission to graduate professional schools—the LSAT, GMAT, MCAT, and so on. Obviously, the designers of these tests recognize that the ability to reason logically is a prerequisite to success in these ? elds. The appendix in the back of the book contains sample questions and cues on answering them. Also, logic is a useful tool in relieving what has come to be called math anxiety. For whatever reason, countless students today are terri? ed of any form of reasoning that involves abstract symbols.If you happen to be one of these students, you should ? nd it relatively easy to master the use of logical symbols, and your newly found comfort with these symbols will carry over into the other, more di? cult ? elds. To improve your performance in logic, I strongly urge you to take full advantage of a multimedia program called Learning Logic. This is an interactive tutorial that teaches the essentials of this textbook in a very user-friendly way. However, your computer mu st be equipped with loudspeakers or headphones, because the audio component is essential.Learning Logic is available both on CD and online at the Logic CourseMate site. If the CD version or a passcode for the website did not come with your textbook, it can be purchased separately through your campus bookstore if your instructor has ordered it. You can also order it directly at www. cengagebrain. com. In addition to Learning Logic, an eBook and other quizzes and self-study material are available on the Logic CourseMate site. Also available online through the Logic CourseMate site are brief video lectures on key topics. The videos include pointers on how to work the pertinent exercises in the textbook.They cover topics such as the concept of validity, conversion, obversion, and contraposition, indirect truth tables, and natural deduction. If, as you work through the content of this book, you encounter a subject that you have trouble understanding, one of these videos may solve the pro blem. Additionally, a set of audio summaries for each chapter in the book is available. These are designed so that you can download them onto your iPod, mp3 player, or computer and listen to them before taking a test. Because pro? ciency in logic involves developing a kill, it helps to work through the practice problems in Learning Logic and the exercises in the textbook more than once. This will help you see that good reasoning (and bad reasoning, too) follows certain patterns whose identi? cation is crucial to success in logic. As you progress, I think you will ? nd that learning logic can be lots of fun, and working with the online resources should enhance your overall learning experience. Note to the Instructor With this eleventh edition, Learning Logic is available both on CD and online. The CD comes free if  ordered with a new book, or it can be ordered separately at www. engagebrain. com. Online, Learning Logic it is available through the Logic CourseMate site, a password p rotected website (www. cengage. com/sso). This website o? ers the bene? t of being able to check a student’s â€Å"time on task,† that is, how much time the student has spent using a particular supplement. â€Å"Critical Thinking and Writing† and â€Å"Truthtrees† are available free on the website, and they can also be selected as modules in a custom version of the textbook. The videos, which cover topics students often have trouble with, are also available on Logic CourseMate.This edition also features Aplia, one of the Cengage Learning CourseMaster digital solutions. Aplia established a name for itself in the ? eld of economics, where it o? ers interactive online homework xvi Preface Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed cont ent does not materially affect the overall learning experience.Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. assignments with continuous feedback to students. Providing automatic grading, Aplia increases student effort and keeps students accountable for course material while adding no additional paperwork to the instructor’s workload, leaving instructors with more time to prepare lectures and work with students. As Aplia expands its o? erings to include additional subjects, it has won widespread acclaim from thousands of instructors across numerous disciplines. Now, Aplia o? ers its signature bene? s to logic students and instructors with a program speci? cally designed to enhance student engagement. The Aplia assignments build on the exercises in this textbook, and they conform to the language, style, and structure of the book. Let me now turn to alternate ways of approaching the textbook. In genera l, the material in each chapter is arranged so that certain later sections can be skipped without a? ecting subsequent chapters. For example, those wishing a brief treatment of natural deduction in both propositional and predicate logic may want to skip the last three sections of Chapter 7 and the last four (or even ? e) sections of Chapter 8. Chapter 2 can be skipped altogether, although some may want to cover the ? rst section of that chapter as an introduction to Chapter 3. Finally, Chapters 9 through 14 depend only slightly on earlier chapters, so these can be treated in any order one chooses. However, Chapter 14 does depend in part on Chapter 13. Type of Course Traditional logic course Recommended material Chapter 1 Chapter 3 Chapter 4 Chapter 5 Chapter 6 Sections 7. 1–7. 4 Informal logic course, critical reasoning course Chapter 1 Chapter 2 Chapter 3 Chapter 4 Sections 5. 1–5. Sections 5. 5–5. 6 Sections 6. 1–6. 4 Section 6. 6 Chapter 9 Chapter 12 C hapter 13 Chapter 14 Writing Supplement Section 5. 4 Section 5. 7 Section 6. 5 Chapter 10 Chapter 11 Course emphasizing modern formal logic Chapter 1 Sections 4. 1–4. 3 Section 4. 7 Sections 6. 1–6. 5 Chapter 7 Chapter 8 Truth Tree Supplement Optional material Chapter 2 Sections 7. 5–7. 7 Chapters 9–14 Chapter 3 Sections 4. 4–4. 6 Sections 5. 1–5. 2 Section 5. 7 Section 6. 6 Preface xvii Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part.Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Acknowledgements For their reviews and suggestions leading to this eleventh edition I want to thank the following: Kevin Berry Scott Calef Gabriel Camacho Loren Cannon Victor Cosculluela Thompson Faller Thomas J.Frost Paul Gass Alexander Hall Courtney Hammond Merle Harton Anthony Hanson Ron Jackson William Jamison Sandra Johanson Richard Jones Russel Jones William Lawhead Stephen Leach Keane Lundt Erik Meade Ian MacKinnon Allyson Mount Seyed Mousavian Madeline Muntersbjorn Herminia Reyes Frank Ryan Eric Saidel Stephanie Semler Janet Simpson Aeon Skoble Joshua Smith Paula Smithka Krys Sulewski Brian Tapia William Vanderburgh Mark Vopat David Weise Shannon Grace Werre Katherine D.Witzig Stephen Wykstra Ohio University Ohio Wesleyan University El Paso Community College Humboldt State University Polk State College University of Portland Biola University/Long Beach City College Coppin State University Clayton State University Cuyamaca College Edward Waters College West Valley College Clayton State University University of Alaska Anchorage Green River Community College Howard University Uni versity of Oklahoma University of Mississippi UTPA Massachusetts College of Liberal Arts Southern Illinois University–Edwardsville The University of Akron Keene State College University of Alberta University of Toledo San Diego State University Kent State University George Washington University Radford University Su? olk County Community College Bridgewater State College Central Michigan University University of Southern Mississippi Edmonds Community College Foothill College Wichita State University Youngstown State University Gonzaga University Edmonds Community College Southwestern Illinois College Calvin College Of course any errors or omissions that may remain are the result of my own oversight. xviii Preface Copyright 2010 Cengage Learning. All Rights Reserved.May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppresse d content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Those who have contributed reviews and suggestions leading to the ten previous editions, and to whom I express my continued thanks, are the following: James T. Anderson, University of San Diego; Carol Anthony, Villanova University; Joseph Asike, Howard University; Harriet E.Baber, University of San Diego; Kent Baldner, Western Michigan University; James Baley, Mary Washington College; Jerome Balmuth, Colgate University; Victor Balowitz, State University of New York, College at Buffalo; Ida Baltikauskas, Century College; Gary Baran, Los Angeles City College; Robert Barnard, University of Mississippi; Gregory Bassham, Kings College; Thora Bayer, Xavier University of Louisiana; David Behan, Agnes Scott College; John Bender, Ohio University, Athens; James O. Bennett, University of Tennessee, Knoxv ille; Victoria Berdon, IUPU Columbus; Robert Berman, Xavier University of Louisana; Joseph Bessie, Normandale Community College; John R. Bosworth, Oklahoma State University; Andrew Botterell, University of Toronto; Tom Browder, University of Nevada, Las Vegas; Kevin Browne, Indiana University Southeast; Harold Brown, Northern Illinois University; KenBuckman, University of Texas, Pan American; Robert Burch, Texas A&M University; Keith Burgess-Jackson, University of Texas, Arlington; Michael Byron, Kent State University; James Campbell, University of Toledo; Joseph Keim Campbell, Washington State University; Charles Carr, Arkansas State University; William Carroll, Coppin State University; Jennifer Caseldine-Bracht, IUPU Fort Wayne; John Casey, Northern Illinois University; Greg Cavin, Cypress College; Robert Greg Cavin, Cypress College; Ping-Tung Chang, University of Alaska; Prakash Chenjeri, Southern Oregon University; Drew Christie, University of New Hampshire; Timothy Christion, U niversity of North Texas; Ralph W. Clarke, West Virginia University; David Clowney, Rowan University; Michael Cole, College of William and Mary; Michael J. Colson, Merced College; William F. Cooper, Baylor University; William Cornwell, Salem State College; Victor Cosculluela, Polk Community College; Mike Coste, Front Range Community College; Ronald R. Cox, San Antonio College; Houston A. Craighead, Winthrop University; Donald Cress, Northern Illinois University, DeKalb; Jack Crumley, University of San Diego; Linda Damico, Kennesaw State University; William J.DeAngelis, Northeastern University; Joseph DeMarco, Cleveland State University; Paul DeVries, Wheaton College; Jill Dieterle, Eastern Michigan University; Mary Domski, University of New Mexico; Beverly R. Doss and Richard W. Doss, Orange Coast College; Paul Draper, Purdue University; William A. Drumin, King’s College, Pennsylvania; Clinton Dunagan, Saint Philips College; Paul Eckstein, Bergen Community College; Anne M. Ed wards, Austin Peay State University; Lenore Erickson, Cuesta College; Michael Epperson, California State University, Sacramento; Cassandra Evans, San Diego City College; Evan Fales, University of Iowa; Lewis S. Ford, Old Dominion University; Gary Foulk, Indiana State University, Terre Haute; LeAnn Fowler, Slippery Rock University; Thomas H. Franks, Eastern Michigan University; Bernard D.Freydberg, Slippery Rock University; Frank Fair, Sam Houston State University; Timothy C. Fout, University of Louisville; Craig Fox, California University of Pennsylvania; Dick Gaffney, Siena College; George Gale, University of Missouri, Kansas City; Pieranna Garavaso, University of Minnesota at Morris; Joseph Georges, El Camino College; Kevin Gibson, University of Colorado; Victor Grassian, Los Angeles Harbor College; J. Randall Groves, Ferris State University; Shannon Grace, Edmunds Community College; James Granitto, Santiago Canyon College; Catherine Green, Rockhurst University; James Greene, Nort hern Michigan University; Harold Greenstein, SUNY Brockport; Shahrokh Haghighi, California State University; Alexander W.Hall, Clayton State University; Dean Hamden, Montclair State University; Ken Hanly, Brandon University; Larry Hauser, Alma College; Deborah Heikes, University of Alabama in Huntsville; Ronald Hill, University of San Diego; Lawrence Hinman, University of San Diego; Preface xix Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Dale Lynn Holt, Mississippi State University; John B.Howell, III, Southwestern Baptist Theological Seminary; R. I. G. Hughes, University o f South Carolina, Columbia; Lynn Holt, Mississippi State University; Peter Hutcheson, Texas State University; Debby D. Hutchins, Boston College; William H. Hyde, Golden West College; Sandra Johanson, Green River Community College; Gary Jones, University of San Diego; Glenn C. Joy, Texas State University, San Marcos; Olin Joynton, North Harris County College; Grant Julin, St. Francis University; Glen Kessler, University of Virginia; Charles F. Kielkopf, Ohio State University; Moya Kinchla, Bakersfield College; Bernard W. Kobes, Arizona State University; Keith W.Krasemann, College of DuPage; Richard La Croix, State University College at Buffalo; Sandra LaFave, West Valley College, Saratoga, California; Richard Lee, University of Arkansas; Lory Lemke, University of Minnesota, Morris; Robert Levis, Pasadena City College; Chenyang Li, Monmouth College, Monmouth, Illinois; Ardon Lyon, City University of London; Scott MacDonald, University of Iowa; Krishna Mallick, Salem State College; Tho mas Manig, University of Missouri, Columbia; James Manns, University of Kentucky; Dalman Mayer, Bellevue Community College; Larry D. Mayhew, Western Kentucky University; Leemon McHenry, California State University, Northridge; Robert McKay, Norwich University; Rick McKita, Colorado State University; Phillip McReynolds, Pennsylvania State University; Noel Merino, Humboldt State University; Kenneth R.Merrill, University of Oklahoma; Thomas Michaud, Wheeling Jesuit College; Dolores Miller, University of Missouri, Kansas City; George D. Miller, DePaul University; Richard Miller, East Carolina University; Frederick Mills, Bowie State University; Jeff Mitchell, Arkansas Tech University; John Mize, Long Beach City College; Dwayne Mulder, California State University, Fresno; John D. Mullen, Dowling College; Henry Nardone, Kings College; Theresa Norman, South Texas Community College; David O’Connor, Seton Hall University; Len Olsen, Georgia Southern University; Elane O’Rourke, Moorpark College; Brendan O’Sullivan, Rhodes College; Linda Peterson, University of San Diego; Rodney Peffer, University of San Diego; Robert G.Pielke, El Camino College; Cassandra Pinnick, Western Kentucky University; Nelson Pole, Cleveland State University; Norman Prigge, Bakersfield State University; Gray Prince, West Los Angeles College; R. Puligandla, University of Toledo; T. R. Quigley, Oakland University; Nani Rankin, Indiana University at Kokomo; Robert Redmon, Virginia Commonwealth University; Bruce Reichenbach, Augsburg College; David Ring, Southern Methodist University; Tony Roark, Boise State University; Michael Rooney, Pasadena City College; Phyllis Rooney, Oakland University; Beth Rosdatter, University of Kentucky; Michelle M. Rotert, Rock Valley College; Paul A. Roth, University of Missouri, Saint Louis; Daniel Rothbart, George Mason University; Robert Rupert, University of Colorado, Boulder; Sam Russo, El Camino College; Kelly Salsbery, Stephen F.Austin State University; Eric Saidel, George Washington University; Paul Santelli, Siena College; Stephen Satris, Clemson University; Phil Schneider, Coastal Carolina University; Philip Schneider, George Mason University; James D. Schumaker, University of North Carolina at Charlotte; Stephanie Semler, Radford University; Pat Sewell, University of North Texas; Elizabeth Shadish, El Camino College; Joseph G. Shay, Boston College; Dennis L. Slivinski, California State University, Channel Islands; Arnold Smith, Youngstown State University; JohnChristian Smith, Youngstown State University; Paula Smithka, University of Southern Mississippi; Eric W.Snider, University of Toledo; Bob Snyder, Humboldt University; Joseph Snyder, Anne Arundel Community College; Lynne Spellman, University of Arkansas; David Stern, University of Iowa; James Stuart, Bowling Green State University; John Sullins, Sonoma State University; John Sweigart, James Madison University; Clarendon Swift, Moorpark College; Wayne Swindall, California Baptist College; Bangs Tapscott, University of Utah; Ramon Tello, Shasta College; Jan Thomas, University of Arkansas at Little Rock; Phil Thompson, Eastern Illinois University; Richard Tieszen, San Jose State University; Larry Udell, West Chester University; Ted Ulrich, Purdue xx Preface Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. University; Robert Urekew, University of Louisville; William Uzgalis, Oregon State University; Thomas H. Warren, Solano Colleg; Andrew J.Waskey, Dalton State University; Roy Weatherford, University of South Florida; Chris Weigand, Our L ady of the Lake University; David Weinburger, Stockton State College; Paul Weirich, University of Missouri, Columbia; Robert Wengert, University of Illinois, Urbana/Champaign; Gerald Joseph Williams, Seton Hall University; Frank Wilson, Bucknell University; W. Kent Wilson, University of Illinois, Chicago; Stephen Wykstra, Calvin College; Marie Zaccaria, Georgia Perimeter College; Jeffrey Zents, University of Texas; Finally, it has been a pleasure working with philosophy editor Joann Kozyrev, development editor Florence Kilgo, project manager Alison Eigel Zade, project editors Emily Winders and Amanda Hellenthal, and editorial assistant Michaela Henry. Preface xxi Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 1 Basic Concepts 1. 1 1. 2 1. 3 1. 4 1. 5 1. Arguments, Premises, and Conclusions Recognizing Arguments Deduction and Induction Validity, Truth, Soundness, Strength, Cogency Argument Forms: Proving Invalidity Extended Arguments 1. 1 Arguments, Premises, and Conclusions Logic may be de? ned as the organized body of knowledge, or science, that evaluates arguments. All of us encounter arguments in our day-to-day experience. We read them in books and newspapers, hear them on television, and formulate them when communicating with friends and associates. The aim of logic is to develop a system of methods and principles that we may use as criteria for evaluating the arguments of others and as guides in constructing arguments of our own.Among the bene? ts to be expected from the study of logic is an increase in con? dence that we are making sense when we criticize the arguments of others and when we advance arguments of our own. An argument, in its most basic form, is a group of statements, one or more of which (the premises) are claimed to provide support for, or reasons to believe, one of the others (the conclusion). All arguments may be placed in one of two basic groups: those in which the premises really do support the conclusion and those in which they do not, even though they are claimed to. The former are said to be good arguments (at least to that extent), the latter bad argu ments.The purpose of logic, as the science that evaluates arguments, is thus to develop methods and techniques that allow us to distinguish good arguments from bad. As is apparent from the given definition, the term argument has a very specific meaning in logic. It does not mean, for example, a mere verbal ? ght, as one might  have with one’s parent, spouse, or friend. Let us examine the features of this de? nition in Additional resources are available on the Logic CourseMate website. 1 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 1 greater detail. First of all, an a rgument is a group of statements. A statement is a sentence that is either true or false—in other words, typically a declarative sentence or a sentence component that could stand as a declarative sentence. The following sentences are statements: Chocolate truffles are loaded with calories. Melatonin helps relieve jet lag. Political candidates always tell the complete truth.No wives ever cheat on their husbands. Tiger Woods plays golf and Maria Sharapova plays tennis. The first two statements are true, the second two false. The last one expresses two statements, both of which are true. Truth and falsity are called the two possible truth values of a statement. Thus, the truth value of the ? rst two statements is true, the truth value of the second two is false, and the truth value of the last statement, as well as that of its components, is true. Unlike statements, many sentences cannot be said to be either true or false. Questions, proposals, suggestions, commands, and exclama tions usually cannot, and so are not usually classi? ed as statements.The following sentences are not statements: Where is Khartoum? Let’s go to a movie tonight. I suggest you get contact lenses. Turn off the TV right now. Fantastic! (question) (proposal) (suggestion) (command) (exclamation) The statements that make up an argument are divided into one or more premises and one and only one conclusion. The premises are the statements that set forth the reasons or evidence, and the conclusion is the statement that the evidence is claimed to support or imply. In other words, the conclusion is the statement that is claimed to follow from the premises. Here is an example of an argument: All film stars are celebrities. Halle Berry is a film star.Therefore, Halle Berry is a celebrity. The ? rst two statements are the premises; the third is the conclusion. (The claim that the premises support or imply the conclusion is indicated by the word â€Å"therefore. †) In this argument the premises really do support the conclusion, and so the argument is a good one. But consider this argument: Some film stars are men. Cameron Diaz is a film star. Therefore, Cameron Diaz is a man. In this argument the premises do not support the conclusion, even though they are claimed to, and so the argument is not a good one. One of the most important tasks in the analysis of arguments is being able to distinguish premises from conclusions.If what is thought to be a conclusion is really a premise, and vice versa, the subsequent analysis cannot possibly be correct. Many  arguments 2 Chapter 1 Basic Concepts Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to r emove additional content at any time if subsequent rights restrictions require it. contain indicator words that provide clues in identifying premises and conclusion.Some typical conclusion indicators are therefore wherefore thus consequently we may infer accordingly we may conclude it must be that for this reason so entails that hence it follows that implies that as a result 1 Whenever a statement follows one of these indicators, it can usually be identi? ed as the conclusion. By process of elimination the other statements in the argument are the premises. Example: Tortured prisoners will say anything just to relieve the pain. Consequently, torture is not a reliable method of interrogation. The conclusion of this argument is â€Å"Torture is not a reliable method of interrogation,† and the premise is â€Å"Tortured prisoners will say anything just to relieve the pain. † Premises Claimed evidence Conclusion What is claimed to follow from the evidenceIf an argument does not contain a conclusion indicator, it may contain a premise indicator. Some typical premise indicators are since as indicated by because for in that may be inferred from as given that seeing that for the reason that in as much as owing to Any statement following one of these indicators can usually be identi? ed as a premise. Example: Expectant mothers should never use recreational drugs, since the use of these drugs can jeopardize the development of the fetus. The premise of this argument is â€Å"The use of these drugs can jeopardize the development of the fetus,† and the conclusion is â€Å"Expectant mothers should never use recreational drugs. In reviewing the list of indicators, note that â€Å"for this reason† is a conclusion indicator, whereas â€Å"for the reason that† is a premise indicator. â€Å"For this reason† (except Section 1. 1 Arguments, Premises, and Conclusions 3 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 1 hen followed by a colon) means for the reason (premise) that was just given, so what follows is the conclusion. On the other hand, â€Å"for the reason that† announces that a premise is about to be stated. Sometimes a single indicator can be used to identify more than one premise. Consider the following argument: It is vitally important that wilderness areas be preserved, for wilderness provides essential habitat for wildlife, including endangered species, and it is a natural retreat from the stress of daily life. The premise indicator â€Å"for† goes with both â€Å"Wilderness provide s essential habitat for wildlife, including endangered species,† and â€Å"It is a natural retreat from the stress of daily life. These are the premises. By method of elimination, â€Å"It is vitally important that wilderness areas be preserved† is the conclusion. Some arguments contain no indicators. With these, the reader/listener must ask such questions as: What single statement is claimed (implicitly) to follow from the others? What is the arguer trying to prove? What is the main point in the passage? The answers to these questions should point to the conclusion. Example: The space program deserves increased expenditures in the years ahead. Not only does the national defense depend on it, but the program will more than pay for itself in terms of technological spinoffs.Furthermore, at current funding levels the program cannot fulfill its anticipated potential. The conclusion of this argument is the ? rst statement, and all of the other statements are premises. The a rgument illustrates the pattern found in most arguments that lack indicator words: the intended conclusion is stated ? rst, and the remaining statements are then o? ered in support of this ? rst statement. When the argument is restructured according to logical principles, however, the conclusion is always listed after the premises: P1: P2: P3: C: The national defense is dependent on the space program. The space program will more than pay for itself in terms of technological spinoffs.At current funding levels the space program cannot fulfill its anticipated potential. The space program deserves increased expenditures in the years ahead. When restructuring arguments such as this, one should remain as close as possible to the original version, while at the same time attending to the requirement that premises and conclusion be complete sentences that are meaningful in the order in which they are listed. Note that the ? rst two premises are included within the scope of a single sentence in the original argument. For the purposes of this chapter, compound arrangements of statements in which the various components are all claimed to be true will be considered as separate statements.Passages that contain arguments sometimes contain statements that are neither premises nor conclusions. Only statements that are actually intended to support the conclusion should be included in the list of premises. If, for example, a statement 4 Chapter 1 Basic Concepts Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s). Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. erves merely to introduce the general topic, or merely makes a pas sing comment, it should not be taken as part of the argument. Examples: The claim is often made that malpractice lawsuits drive up the cost of health care. But if such suits were outlawed or severely restricted, then patients would have no means of recovery for injuries caused by negligent doctors. Hence, the availability of malpractice litigation should be maintained intact. Massive federal deficits push up interest rates for everyone. Servicing the debt gobbles up a huge portion of the federal budget, which lowers our standard of living. And big deficits also weaken the value of the dollar. For these reasons, Congress must make a determined effort to cut overall spending and raise taxes.Politicians who ignore this reality imperil the future of the nation. 1 In the ? rst argument, the opening statement serves merely to introduce the topic, so it is not part of the argument. The premise is the second statement, and the conclusion is the last statement. In the second argument, the ? nal statement merely makes a passing comment, so it is not part of the argument. The premises are the ? rst three statements, and the statement following â€Å"for these reasons† is the conclusion. Closely related to the concepts of argument and statement are those of inference and proposition. An inference, in the narrow sense of the term, is the reasoning process expressed by an argument.In the broad sense of the term, â€Å"inference† is used interchangeably with â€Å"argument. † Analogously, a proposition, in the narrow sense, is the meaning or information content of a statement. For the purposes of this book, however, â€Å"proposition† and â€Å"statement† are used interchangeably. Note on the History of Logic The person who is generally credited as the father of logic is the ancient Greek philosopher Aristotle (384–322 b. c. ). Aristotle’s predecessors had been interested in the art of constructing persuasive arguments and in techniques for refuting the arguments of others, but it was Aristotle who ? rst devised systematic criteria for analyzing and evaluating arguments.Aristotle’s chief accomplishment is called syllogistic logic, a kind of logic in which the fundamental elements are terms, and arguments are evaluated as good or bad depending on how the terms are arranged in the argument. Chapters 4 and 5 of this textbook are devoted mainly to syllogistic logic. But Aristotle also deserves credit for originating modal logic, a kind of logic that involves such concepts as possibility, necessity, belief, and doubt. In addition, Aristotle catalogued several informal fallacies, a topic treated in Chapter 3 of this book. After Aristotle’s death, another Greek philosopher, Chrysippus (280–206 b. c. ), one of the founders of the Stoic school, developed a logic in which the fundamental elements were whole propositions.Chrysippus treated every proposition as either true or false and developed rules for determining the truth or falsity of compound propositions from the truth or falsity of their components. In the course of doing so, he laid the foundation for the truth functional interpretation of the logical connectives presented in Chapter 6 of this book and introduced the notion of natural deduction, treated in Chapter 7. Section 1. 1 Arguments, Premises, and Conclusions 5 Copyright 2010 Cengage Learning. All Rights Reserved. May not be copied, scanned, or duplicated, in whole or in part. Due to electronic rights, some third party content may be suppressed from the eBook and/or eChapter(s).Editorial review has deemed that any suppressed content does not materially affect the overall learning experience. Cengage Learning reserves the right to remove additional content at any time if subsequent rights restrictions require it. 1 For thirteen hundred years after the death of Chrysippus, relatively little creative work was done in logic. The physician Galen (a. d. 129†“ca. 199) developed the theory of the compound categorical syllogism, but for the most part philosophers con? ned themselves to writing commentaries on the works of Aristotle and Chrysippus. Boethius (ca. 480–524) is a noteworthy example. The ? rst major logician of the Middle Ages was Peter Abelard (1079–1142). Abelard reconstructed and re? ed the logic of Aristotle and Chrysippus as communicated by Boethius, and he originated a theory of universals that traced the universal character of general terms to concepts in the mind rather than to â€Å"natures† existing outside the mind, as Aristotle had held. In addition, Abelard distinguished arguments that are  valid because of their form from those that are valid because of their content, but he held that only formal validity is the â€Å"perfect† or conclusive variety. The present text