Forever Undecided [Paperback]

Raymond Smullyan (Author)

Book Description

Publication Date: November 30, 2000

A challenging puzzle collection and an instructive and entertaining introduction to Kurt Godel's famous theorems, including incompleteness and undecidability. Much of the action of the book takes place on an imaginary and magical island, the Island of Knights and Knaves, where knights always make true statements, knaves always make false statements, and every inhabitant is either a knight or a knave. Here we meet an amazing array of characters, visitors to the island, seeking to determine the natives' true identities. Among them are the census-taker McGregor; a philosopher-logician in search of his flighty bird-wife Oona; and a regiment of Reasoners. By following the Reasoners through brain-tingling exercises and adventures - including journeys into the "other possible worlds" of Kripke semantics - even the most illogical of us should come to understand Godel's theorems, some of their philosophical and mathematical implications and why we, like Godel himself, must remain forever undecided! The book is intended for puzzle fans of every age and ability - from the high-school whizz to the seasoned mathematician, logician or computer scientist.

Editorial Reviews

From Publishers Weekly

In these mathematical and logic puzzles, truth-telling knights battle lying knaves; a philosopher-logician named George falls in love with Oona, flighty bird-girl of the South Pacific; Inspector Craig and timid, conceited or modest reasoners match wits. Using such fictional enticements, the author of What Is the Name of This Book? and To Mock a Mockingbird steers us through the logical thickets of Kurt Godel's famous Incompleteness Theorem, which holds that mathematical systems can never prove their own consistency. Readers who make it halfway through this book will learn more symbolic logic than a college freshman stuffed with "new math." In the second half, the deeper waters of modal logic are navigated. This field, which dates back to Aristotle, impinges on current debates in computer science and artificial intelligence. Smullyan's gift is to make complex ideas both accessible and enjoyable to the persevering reader.
Copyright 1987 Reed Business Information, Inc. --This text refers to an out of print or unavailable edition of this title.

From Library Journal

Godel's incompleteness theorem is generally considered to have shown that formal number systems cannot prove their own consistency. Through a series of problems and solutions ("On the Island of Knights and Knaves, knights always make true statements and knaves always make false statements, and every inhabitant is either a knight or a knave . . . ") that are converted to symbolic logic, Smullyan progresses from an elementary to an advanced consideration of Godel's theorem. Apart from a few remarks at book's end, Smullyan makes no attempt to show what bearing Godel's results might have on more general, particularly epistemological, problems. Serious students of logic, computer theory, and artificial intelligence should find this entertaining and instructive, but it cannot be recommended for a larger audience. Leon H. Brody, U.S. Office of Personnel Management Lib., Washington,
Copyright 1987 Reed Business Information, Inc. --This text refers to an out of print or unavailable edition of this title.

Product Details

• Paperback: 272 pages
• Publisher: Oxford University Press (November 30, 2000)
• Language: English
• ISBN-10: 0192801414
• ISBN-13: 978-0192801418
• Product Dimensions: 7.7 x 5 x 0.8 inches
• Shipping Weight: 11.4 ounces
• Average Customer Review: 4.5 out of 5 stars  See all reviews (4 customer reviews)
• Amazon Best Sellers Rank: #4,055,074 in Books (See Top 100 in Books)

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Customer Reviews

Most Helpful Customer Reviews

18 of 21 people found the following review helpful:

5.0 out of 5 stars Brain candy in a logical form, March 13, 2000

By 

Charles Ashbacher (Marion, Iowa United States) - See all my reviews
(TOP 500 REVIEWER)    (VINE VOICE)    (HALL OF FAME REVIEWER)   

This review is from: Forever Undecided: A Puzzle Guide to Godel (Oxford paperbacks) (Paperback)

Do you believe that you know what you believe? Is it possible to believe only those things that are true? These questions are but two of the many addressed in this book by Professor Smullyan, and the answers will surprise you!
With most of the material in the form of puzzles, and nearly all of them solved, it is possible for a logical novice to read and understand the book. However, it is recommended that you find another source for explanations of the standard logical operators and read it first. Even then, you should not be surprised to find yourself rereading a solution thinking that the answer simply cannot be correct. But keep trying, as eventually you will begin to understand, and come to appreciate some of the unresolvable consequences of mathematics, the most precise of disciplines. For while Professor Smullyan may not be logically consistent, he is consistently logical. (This is of course a bad pun, but it is no worse than some of the groaners in the book.)
Finally, as the following example shows:

"The following dialogue ensues between a student and his theology professor:

Student: If I believe that God exists, then I will also believe that I will be saved?
Professor: It that is true, then God exists.
Student: If I believe that God exists, then will I be saved?
Professor: If God exists, then that is true.

Prove that if the professor is accurate and if the student believes the professor, then God must exist and the student will be saved"

You may also be given insight into one of the most fundamental questions regarding human existence.

Published in Journal of Recreational Mathematics, reprinted with permission.

2 of 3 people found the following review helpful:

5.0 out of 5 stars Logic in ready-to-use, bit-sized chunks, January 4, 2009

By 

Epictetus "Epictetus" (City of London United Kingdom) - See all my reviews

This review is from: Forever Undecided: A Puzzle Guide to Godel (Oxford paperbacks) (Paperback)

This book was recommended (an aeon ago) in my undergraduate philosophy class, with the recommendation that if one will bother to think through each example, then one will become very good at formal logic. Many years later I have found time to do this. So many things can keep me awake at night, idle thoughts, terror at the credit crisis, and so on. Now I read one puzzle from Smullyan, and gently tug my mind back to it if it wanders as I lie in bed. This has been a revolution for me. Either I learn something or I sleep better.

This book hits the happy medium between on the one hand an overly formal approach to logic such that it is unsuitable for anything but hard work or formal study and on the other a text that is watered down to the extent of being useless.

I do not recommend my particular way of reading this as the only way or the best way, but merely as an example of how it has worked very well for me. The practical benefit of using this book and learning from it is that one can grasp arguments and any problem in them much more rapidly than before, both in work and non-work life.

I recommend this book very highly to anyone at any level who is interested in logic, language, problem solving or reasoning.

EPICTETUS

7 of 25 people found the following review helpful:

5.0 out of 5 stars Unique method uses puzzles to explain Go:del's theorem, September 2, 1998

By A Customer

This review is from: Forever Undecided: A Puzzle Guide to Godel (Hardcover)

This is a great book for anyone wanting to understand Go:del's theorem, which basically proves that logic is inherently flawed. The book is very readable. Just make sure that you don't let your head explode.