Introduction Linguistics has both practical and philosophica

introduction
    Since antiquity interest in linguistis--the study and science of human language--has had both practical and philosophical motivations. From a practical side, linguistics can provide a theoretical basis for a variety of practical applications. To name a few, these applications include the treatment of language disorders such as aphasia or reading problems, the planning of " language arts" curricula in the schools, the fight against illiterarcy in many nations of the world, the development of automatic, computer-generated speech productional recognition, the learning of foreign languages, and the simplification of legal language. Philosophical interests have ’also spurred language study, because from earliest times language has been considered a mirror of the mind.
    For these reasons both the first and second editions of this text were directed toward students of many disciplines. This book is used in courses for nonlinguisties as well as linguistics students, tbr majors in computer science and English in speech pathology and anthropology, in communications studies and philosophy.  This third edition continues and further develops this approach. It does, however, reflect new thinking is the field as well as a reorganization of material.
    We have aimed to dispel a number of myths about language and to discuss the various aspects of language from both an historical and current point of view. Part One, lesson one, "The Nature of Human Language", is concerned with questions such as: What is language? What is a grammar? What is the origin of language?
    What it is you know when you know English, Zulu, Twi, Cherokee, Eskimo, Spanish, B.ussian, and any other language is examined in Lesson Two, "Grammatical Aspects of Language. " Lesson 2 discusses speech sounds or phonetics and it includes an expanded section on machines that "talk" and " understand. " Lesson 3 on phonology demonstrates how sounds form pattens. Lesson 5 shows that written forms of language arose very late in the history, of hnman language. Lesson 4, 6, and 7 discuss other grammatical aspects of language--how words are formed (morphology); what words, phrases, and sentences mean (semantics); and how words are put together to form sentences syntax. These lessans have been substantially revised since the second edition. Although a formal descrptive apparatus is still included, it receives less emphasis; distinction between phonetic and phonemic segments and phonological and morphophonemic rules are clarified ;and the section on pragmatics is enlarged.
    Lessons 8 and 9 of Part Three, "Social Aspects of Language", considering language in society and how languages change over time. Some of the questions raised in this part are: Why are there many tang nages and how are they related? How and why do languages change? Are some languages or dialects superior to others? Is there any hope for a universal language? Can language be "obscene" or "sexist"?
    Part Four, "The Biological Aspects of Language", includes Lesson 10 on child language, Lesson 11 on animal communication systems, and lesson 12 on brain mechanisms underlying language knowledge and use. These lessons have been expanded considerably. The sign language of the deaf, especially AMESLAN (American Sign Language) , are discussed in greater detail. The newest findings on whether chimpanzees and gorillas can learn language are presented, as are the latest techniques for brain and language studies. In every lesson the universals underlying the diversity of phenomena observed in human language are highlighted.
    As in the previous editions basic ideas rather than a detailed exposition of the grammar of English or any other language have been primarily concerned with. The text assumes no previous knowledge on the part of the students and aims at stimulating the students to further investigate language, this incredibly complex, unique human ability. Toward this goal a short list of references is given at the end of each lesson. Also included are exercises ranging in difficulty and type to enhance the students’ interest in and comprehension of the textual material.
    We have had enormous help from friends, colleagues, students, teaching assistants, instructors who assigned the text to their classes, and reviewers. We wish to convey our profound gratitude to all of the individuals who provided feedback, criticisms, corrections, and suggestions. We continue to be especially grateful to the thousands of students who have listened to our lectures, questioned our concepts, completed our assignments, and in these and other ways helped us to rewrite this book.