Introduction to Logic

by Irving M. Copi

This book introduces the fundamental methods and techniques of correct reasoning, in a manner that shows the relevance of the topics to readers¿ everyday lives. Many new exercises introduced in this edition help supplement and support explanations, aid in review, and make the book visually stimulating. This edition also includes a revised Logic tutorial on CD-Rom--further simplifying the study of logic. Includes many fascinating illustrations taken from the history of science as well as from contemporary research in the physical and biological sciences, plus introduces an abundance of new exercises throughout, complete with solutions for the first exercise in a set. Appropriate for those in business, education, political, or psychology careers.

Genres: Philosophy, Logic, Nonfiction, Textbooks, Reference, Mathematics, Science

683 pages, Paperback

First published January 1, 1953

Reviews

[Xeon · Rating 5 out of 5]

As the dewy eyed boy I am, with the tools of logic I shall go forth and try to prove the most difficult thing possible: A proof for God follows (with catastrophically unsound logic of course).

Syllogistic logic

All of the word 'God' (A) is in the word 'Godel' (X).
All the entity God (B) is the word 'God' (A).
All the word 'Godel' (X) is the person Godel (Y).
Therefore God (B) is Godel (Y).
All A is X.
All B is A.
Therefore all B is X.
All X is Y.
All B is X.
Therefore all B is Y.
Tis was a sorites, composed of two categorical syllogisms of figure 1, categorical propositions of universal affirmatives form A, and mood AAA-1 Barbara valid each.
Let us try another means!

Predicate logic

There is some set of 1 word, the subject, composed of the name 'Godel'. Contained within the letters of this individual is the string of letters "God", the predicate.
Let us represent the last name of 'Godel' with the individual variable 'g', and the word 'God' with the predicate symbol 'G'. So, g='Godel', and G='God'.
The simple predicate is Gg.
There is an encompassing set of words that includes all names, whereby x="the domain of all words"
Thus there exists some words composed of the word 'God', whereby the existential instantiation is (∃x)Gx.
If 'Godel' has the word 'God' within it, then the person Godel (=g₂) is the entity God (=G₂). Gg→G₂g₂
For all words, if that word has the word 'God' within it, then the thing that is that word is God. (∀x)(Gx→G₂)

So solid is the argument, let me address common concerns (most certainly not littered with logical fallacies)

Informal logic

1. Everyone says Godel is God. Tis must be right! (ad populum)
2. Think of the children. What will we do without a savior? (ad Misericordiam)
3. However, fake news is a greater issue (red herring)
4. You said the argument was invalid, not false, but as you can see it is valid (straw man)
5. Only a very green blooded hobgoblin would point out the errs of others (ad hominem)
6. I will hug you to death unless you say I am right (ad baculum)
7. So it is said the conclusion that Godel is God is false, however I believe unicorns can in fact exist (ignoratio elenchi)
8. This is right until proven wrong (ad ignorantiam)
9. My cousin's neighbor's cat's pet human says this is correct (ad verecundiam)
10. If Godel is God, then...everyone must be God! (hasty generalization)

(Note: let us ignore the name is spelled 'Gödel', as 'Godel' is occasionally used.)

At this point, I too am perplexed! Not to worry. Assume I made an error while trying to make an error, such is how erroneous I can be.

With this in mind, let me tell you a folly of this logic, this textbook, and of the subject itself.

As evident, here I validly equivocate an attribute of the arbitrary symbolization of two words, but invalidly equivocate that initial equivocation to the attributes of the things themselves. For as far as we know, the person Kurt Gödel was in fact not God, an omniscient omnipotent omnipresent being. I mistook an attribute equivocation of the definiens, of the orthography, to entail the equivocation of the definiendum, of the semantics (though, there may be such cases that happen to be so by chance, which can also be logically symbolized!).

The issue is that, for the amount that is belabored on and on about truth, there is very little discussion of what truth even is. For example, is it the state of affairs that accords with facts of reality ("Energy can not be created or destroyed." correspondence theory), or is it truths derived from definitions themselves ("If Leslie is a bachelor, then Leslie is unmarried." coherence theory)?

Indeed, logic pertains that to form, not necessarily to the contents. However, I believe it is necessary to explicitly mention, however briefly, even in a tiny margin, of approaches to what all truth can mean. To not to abstract this away as well for some "value function." For the excellent breadth of coverage, this was one thing missing.

Tis only logical after all ;)

[Ali · Rating 5 out of 5]

واقعا شاهکاره این کتاب، شاید بهترین کتاب برای فراگیری مقدماتی منطق باشه. در بخش اول کتاب تمام مفاهیم اساسی منطق بخوبی توضیح داده شده و نحوه آنالیز استدلال ها و تاثیرپذیری استدلال ها از کارکردهای متنوع زبان و برخی مفاهیم زبانی مرتبط تشریح شده. در انتهای این بخش اقسام مغالطات غیر صوری رو بررسی میکنه. فصل مغالطات برای هر کسی فارغ از اینکه به منطق یا فلسفه علاقمنده یا نه، میتونه بسیار مثمر ثمر باشه و تنها فصلی از کتابه که میشه بصورت منفرد و بدون هیچ گونه پیش زمینه ای مطالعه کرد.

بخش دوم کتاب به تشریح کامل منطق قدیم (قیاسی) و منطق جدید (سمبلیک) میپردازه. توضیحات بسیار ساده و در عین حال بسیار عمیقه! بعضی مسائل که در کتاب های دیگر منطق بصورت گنگ و مبهم ارائه شده با ظرافت خاصی واکاوی شده. در ضمن از پرداخت به مسائلی که نیاز به پیش زمینه ای در ریاضیات داره من جمله اثبات تمامیت و سازگاری منطق جدید خودداری شده.

بخش سوم کتاب به منطق استقرایی و نقش اون در پژوهش های علمی میپردازه که میتونه درآمد بسیار مناسبی به فلسفه علم باشه. احتمالات هم مختصرا در فصل آخر کتاب بررسی شده.

همه ی این نقاط قوت به کنار، مثال ها چیز دیگریست. هر چی از مثال ها بگم کم گفتم. اکثر مثال ها از دعاوی حقوقی، مباحثات سیاسی، کتب فلسفی و ادبی و مجلات و روزنامه ها برگرفته شده. مثال ها باعث میشه که اهمیت منطق در زندگی روزمره کاملا حس بشه

[Brian · Rating 4 out of 5]

a popular college logic textbook...I enjoyed it so much I've read it almost three times now (I realize I must have issues)

[Farjam · Rating 4 out of 5]

Introduction to Logic is an invaluable resource for students of philosophy or mathematics. Despite its initial publication in 1953, the book maintains its relevance and significance. It is essential for individuals genuinely interested in acquiring a comprehensive understanding of the subject matter. The book is divided into three parts: 1- Logic and Language, 2- Deduction, and 3- Induction.
I approached the book with less dedication, leading me to skip specific chapters. Notably, I found Part II of the book, which explores syllogism and symbolic logic, quite dull. However, numerous individuals likely hold contrasting perspectives on the matter. Initially, I grabbed this book to learn about the types of fallacies covered in the book's first part. The combination of examples and exercises has tremendously aided my grasp of these topics, and this portion of the book is very intuitive. Additionally, I learned a lot from the chapters on Probability and Science and Hypothesis. Including biographies of famous logicians and mathematicians in various parts of this book is another noteworthy feature.

The titles of the chapters in the book are clear, and the contents are well-organised. So, you can easily navigate through the book and find the relevant chapters or sections that address your particular interests or questions. This flexibility in reading options makes the book suitable for both comprehensive reading and selective referencing.

[Christy Hammer · Rating 4 out of 5]

If I could learn formal logic from Copi, and enough to with Hempel and others to critique social statistics for *not* being deductive and using formal logic enough (my Ph.D. stats prof said he never thought formal logic "got you anywhere..."?) than anybody could learn it from this textbook. (Note: you must get older editions of logic textbooks as the newer ones are all watered-down "baby logic" and cover sometimes as little as half the topics as those classes did 30 years ago.) So goes "decision sciences"? Big (and fat and stupid and lazy) Data, indeed....

[Patrick Peterson · Rating 4 out of 5]

2021-03-27 This was my textbook for college Logic class that I took about 1976. I liked the text and the class very much. I think I did very well in it because of that. I especially liked the Informal Fallacies section since it is so helpful in finding weaknesses in arguments (advertisements, political claims, etc.). When someone tries to "sell" you something that might not be in your best interest, it is very important to think logically. Most politicians, most all bureaucrats, some salesmen, some marketing campaigns, etc. often use fallacies that seem persuasive. Logic is your tool for seeing through the BS.

This is a good book, but for an even better logic book, I recommend "The Art of Reasoning" by David Kelley. See my review of that, if you want to know more.

Another related book that I highly recommend, especially since it is so short, breezy and easy to read and helpful is "How to Lie with Statistics" by Darrell Huff. That book has sold in the millions, or at least hundreds of thousands, for very good (and logical) reasons, not just the "ad populum" fallacious one I just gave you.

[Joan Sebastián Araujo Arenas · Rating 4 out of 5]

Lo que Copi presenta no es sólo una introducción, es un filosofar a martillazos sobre aquellos que desconocíamos todo lo que en estas páginas se explica. Es la piedra en el zapato que, luego de sacarla, resulta ser un diamante. Una herramienta para analizar las argumentaciones de los demás y para formular de mejor forma las nuestras. Aunque, después de todo, lo que buscamos no es la verdad sino la validez.

El resto de la reseña se encuentra en mi blog: https://jsaaopinionpersonal.wordpress...

[James · Rating 5 out of 5]

I read an earlier edition, obviously, because this one was published in 2001 and I read it as the text for a logic class in 1982; however, I still have the book in a handy spot on the shelf, which I can't say about any other book from that year, so it's stayed current and useful - a lot of its content is timeless.
This was a great eye-opener for me; I'd always had a skeptical and questioning way of thinking, but often although I'd have a gut sense that something I was hearing (in a commercial, a political speech, an argument) didn't hold water, I couldn't put my finger on the problem or tell someone else why I wasn't buying it. This book explained logical fallacies and provided the names, and clear examples, of a series of common fallacies and false syllogisms. It has been a huge help in becoming a smarter voter, consumer, and general decision-maker. Can't recommend this one too strongly, especially in this day and age when schools do less and less to teach critical thinking and too much political discourse is logically totally goofy.

[Yumeko (blushes) · Rating 3 out of 5]

Instead of an inverted V for an AND symbol, the book makes use of a dot. There also no ∀ symbol for universal quantification, instead symbolised by (x).
My disappointment is immesurable and my day is ruined.

Less important:
I believe there should've been some degree of talk abt set theory, considering the fact that they did talk abt probability.
The author does explains things fairly well, and it's not too often that you have to look for other sources of explanation, atleast in my case. There are also plenty of exercises, most of which I still have to go through, and it seems to be more structured(and prettier) compared to the 14th edition.

Alot less important:
Stanzi Potenza to me
"Welcome to another episode of 'Why you get no bitches', today we will consider how you try to flex your understanding of the domains, through considering quantifiers, of certain formulae, to make up for the depressed divorcee that is your math teacher never explicitly mentioning them, un-mathematically though certainly platonically, shoving it down your throat. Also remember that maybe if you were to practice all those exercises you would perhaps not be victim to not truly understanding the nuances of what you think is getting into your head. Intellectual life in your locality is also concerned abt your lack of understanding for the Boolean interpretation of Categorical Syllogisms and the concept of obversion, and is also distasteful of your claims like "The A E I O thing is straight bull man, literally just quantifiers" only because you think the symbols of the latter are kind of pretty, aside from what you understand to be redundancy.
That concludes our episode of 'Why you get no bitches', this was a part 1 of the series bashing this dumb hedonistic girlie."
Pretty important actually:
Imagine reading a textbook with someone who's basically prodigious, and them being excited to read with you.
Reads it with Xeon

[Jeremy · Rating 4 out of 5]

Read this as a first-semester senior in college with Dr. Bob Taylor. In a class of 40 or so, I was first in the class all semester, and then on the final exam, I forgot to study an entire section, and I dropped down to second.

I can remember sitting there for a minute after the bell had rung to end the exam hour, and I was stuck on a certain problem. Suddenly it just came to me. I went to Dr. Taylor's office after he had graded them, and I had come up with the correct answer.

[Argin Gerigorian · Rating 5 out of 5]

One of the best textbooks, Copi and Cohen don't miss a thing.

It is very difficult though since they use a lot of symbols and formulas for logical structures.

Logic is similar to learning a new language whether Spanish or Coding, it takes a lot of practice, something that the authors provide at the end of each chapter.

This book was also highly praised by Greg Bahnsen, he recommends it in almost all of his courses on philosophy or logic.

[Fernanda. Ribeiro · Rating 5 out of 5]

If you want to start to study logic, this is the book!

[Alex Ankarr · Rating 4 out of 5]

I got a lot out of it. My hardback edition was also rather beautiful. Sadly I would now be hard pressed to define a syllogism or inductive reasoning!

[Arun Mahendrakar · Rating 5 out of 5]

The book begins with an introduction of the very basic terminology - propositions, premises, and conclusions. It might sound very naive to start this low, but it helped me to refer back to the precise definitions of these words while reading through the rest of the chapters.

Written in plain and simple language, the book covers a breadth of concepts from categorization of fallacies to Venn diagrams to necessary and sufficient conditions. Some of these were new to me while others were a pleasant revival. The exercises and puzzles throughout the book reinforce your understanding of what you just read.

Most of the book concentrates on deductive and inductive reasoning and the author did an excellent job in convincing that they were most crucial components of any logical discussion. I found the last few chapters - Analogical Reasoning through Science and Hypothesis, very interesting. However the chapter on Probability could be better by discussing more real-world scenarios.

[Jacob Aitken · Rating 5 out of 5]

Probably the most universal logic textbook on college campus. It's become a classic at this point. It's hard to justify paying the insane price. Just go for an earlier edition (I used the 9th, which you can find for $2 at amazon, instead of $175). What makes this text unique is its focus on the function of language.

[carl · Rating 5 out of 5]

this is a great book from a great time in my life. taking 15 hours of philosophy courses and intro logic along with formal logic. this was the text for formal/symbolic. im real right brained at times but this was an awesome experience.

[Kenneth Umenthum · Rating 2 out of 5]

I read the free online version (http://intrologic.stanford.edu/public...) so this review is based on that.

Generally an interesting introduction, I wish my undergraduate computer science program covered some of these topics because I took several grad courses (at the same school) that seemed to expect them as prerequisite knowledge. The exercises based on the in-browser interactive theorem prover are fun and cool, seems like they would be a nice toy to play with before jumping into more advanced tools like Isabelle or Coq. I wish the focus was more on higher-order logic (and its predecessor first-order logic which thankfully is introduced in the appendix) rather than Herbrand logic (and its predecessors, propositional and relational logic) since higher-order logic is more like the logic mathematicians, scientists, programmers, etc. use in the real world.

The (online free edition of the) book is pretty poorly edited. There are incorrect references to chapter and section numbers. The exercises at the end of Appendix 1 (Equality) are broken (as of December 2020, the given premises all show up as "error" which makes the tool unusable). There seems to be at least one allusion to a section that is missing entirely. The chapter titled Relational Analysis talks about semantic trees "As with Propositional Logic, ..." but there is no mention of semantic trees in the chapters on propositional logic. The chapter titled Relational Logic talks about applying the quantifier distribution rules in reverse, but these rules were never introduced in the first place (some web searching leads to a Wikipedia article on "Rules of passage" that seem import but missing from this text).

A distinction of notation is made early on, before the meaning of such a distinction is understandable by the reader, between variables (letters towards the end of the alphabet) and constants (letters towards the beginning of the alphabet). The rule is not really mentioned again and not even followed consistently, especially in the interactive exercises. For me this was a source of great confusion especially when Skolem constants and functions were introduced, it was often unclear when these symbols should or shouldn't be treated differently. I was able to complete all exercises with relative ease except, due to this confusion, the exercises in the chapter titled Resolution. The theorem prover doesn't seem to even care what's a constant vs variable, though the semantics explained in the chapter seem to suggest this is an important distinction. Additionally, there are no premises given for these exercises, part of the task is to translate a sentence into the corresponding clausal form, but a mistake here could trivialize the proof. There are potentially multiple ways to do this translation for a given sentence and it was painful to look at the solution and try to see if my premises agreed with those in the solution.

Also in the chapter titled Resolution, there is an "enhanced definition of resolution" that includes a variable renaming $\tau$ for the clause $\Phi$ which is being resolved, and also factors $\Phi'$ and $\Psi'$. If I understand correctly, there is freedom in how these factors and the variable renaming are chosen, but the text says "at no time did we ever have to make an arbitrary assumption or an arbitrary choice of a binding for a variable". It's not clear how an automated theorem prover would iterate through possible factors and variable renamings when trying to apply resolution. It seems this would make resolution much less efficient than what is suggested. Like the other issues I mentioned with this chapter, this also makes the interactive theorem proving exercises very confusing. There's no way to pick a renaming so I guess it picks one that works and you just have to accept it? This is confusing if you had a different (equivalent) naming in mind. Also the factoring is a separate step rather than part of the resolution step. None of this is explained. I gave up on the exercises in this chapter.

[Enrique · Rating 5 out of 5]

Curiously is one of the best Kant introductions, and an easy one.

Let's begin with the main points:

1. Trascendental logic: trascendental logic only operate with the rules of the understanding which are a priori. Translating this to a more or less more clear idea, understanding (verstand) means "intellect". The problem with the word "intellect" is that in english is not used. The translator uses "understanding", but is no the same. Understanding is used as a noun, but we are not accustomed to use it like that, because the real use is a verb, and convert verbs to nouns is not an easy task and is difficult to grasp. Intellect as a noun means "to see into", "to perceive", "be aware", more literal it means "to gather into (oneself)". Understanding doesn't have the same meaning. You can use "I don't understand english" that means: I don't know how to speak it, how to read it, I don't know how to use the words. In contrast in latin you use "nec est intellectus ullus in odore vel sapore" you can translate as "Nor has any understanding of aroma or flavor" but that is not what they mean, they mean "Can not PERCEIVE any aroma or flavor". More interesting you can use the word perceive in the first example "I don't PERCEIVE English" and have a totally different meaning too. Is a problem with almost all the translations, with the notable exception of the italian translations of Kant.

2. Trascendental Logic as intellect journey: as explained before if you try to convey understanding as "I don't understand this or that" you are not following Kant at all. The meaning of understand is "intellect", and Kant tries to show how the "intellect", the part of the soul of men that "perceives", works. This active part that perceives have some rules, you perceive according this rules and this rules are universal. You cannot "understand" a rock, you "perceive" a rock, and the "intellect" is what perceives.

3. Logic as formal logic: the general logic are the rules of thinking and only works with the old logical rules, this part is boring.

Kant really tries to expand logic, the logic that Bertrand Russell used if Kant could see it he will say "what a limited logic".

[Arthur Kyriazis · Rating 5 out of 5]

this is one of the basic texts of intro logic which has gone thru many editions and iterations.

it covers aristotelian logic completely as well as syllogisms, then covers mathematical logic, then proceeds to the meat of logic, true false tables and making out logic charts from sentences. modal logics and alternate logics are discussed.

logic is very important if you want to think clearly, be a scientist or attorney, or if you want to be any kind of programmer.

that language is a kind of set of symbols reducible to math was first intuited by Aristotle, but the getting farther that that, to first order predicate logics, et al., means certain kinds of rules systems can be programmed completely within an AI consistent with Turing and Godel.

That is, to be brief, what the future holds in store for us all.

[Sharon Barrow Wilfong · Rating 4 out of 5]

This book introduces several methods of analyzing truth claims about reality and the universe and how to express these truths using mathematical symbols and formulae. I found some of it interesting, especially the section on argument fallacies but some of it seemed rather redundant. Rather how many different ways can we express "if A is true than B is also true" or conversely, "if C is not always true, then D cannot always (or ever) be true; if F is true, then G must be false..." and so on.

And of course, the formulae get more complicated as the truths build upon each other.

[Dan · Rating 5 out of 5]

Logic: post-structuralism to the contrary, it's what separates "us" from "them."

[Benandvanessa · Rating 5 out of 5]

Yes, I am a geek. This was a textbook. But it's really good!

[Pankhuri]

Brilliant !!!

[Rick Davis · Rating 5 out of 5]

A solid, classic introduction. Copi explains well and uses good examples.

[James Millikan · Rating 5 out of 5]

My logic professor called the Copi and Cohen text a "libraso"—a rather informal way of saying the book is a classic in the field. I couldn't agree more.

The section on diagraming arguments not only provides an excellent primer on the structure of reasoning, but also includes a huge number of examples taken from very interesting primary sources. This means that you learn the elements of logic while also learning key ideas from the history of philosophy.

The section on logical fallacies has forever changed my outlook on the world. When I scroll through Twitter, listen to political discourse, or read the newspaper, I now see fallacious arguments everywhere. This section would make very good complementary reading for a course on rhetoric. Perhaps my favorite part of the book.

Syllogistic reasoning is given a thorough treatment, complete with a clear explanation of how to use a Venn diagram to evaluate validity. It is amazing to see how a visual representation of a syllogism can make clear what at first glance seems unverifiable. If you are looking for an up-to-date treatment of the methods of deduction that have shaped philosophy, mathematics, and science since the time of Aristotle, this book is an excellent choice.

We moved to my professor's own text for the treatment of modern mathematical logic, but the Copi and Cohen text has an extensive treatment of this topic well. The previous sections you can probably teach yourself, but I would recommend a skilled professor to walk you through the complexities of symbolic logic. The final chapters are quite rigorous.

Overall, this is an excellent book that clearly presents the key concepts of college level logic. What makes this a 5-star book is the wealth of examples taken from a huge array of primary sources. Truly a "libraso.”

[Paul · Rating 3 out of 5]

The book might be of interest to some Kant scholars, since it seems that Kant is applying his Transcendental Philosophy to Logic. However, I think it is better if the readers skipped over this to read Critique of Pure Reason or Groundwork of Metaphysics of Morals.

[August Denys · Rating 5 out of 5]

If one is ever into philosophy, yet they are uncertain on the definitions of a few key points of jargon within the philosophical realm, I would recommend this book heavily for its short nature, great definitions, and flowing text.

[John Graham Wilson · Rating 5 out of 5]

I read an earlier version of this book forty years ago and it still impresses me every time I open it. Irving Copi is the best on the market: very thorough, filled with examples, concentrates a lot on ordinary language. A must for writers who want to make strong arguments.

[Daniel · Rating 3 out of 5]

Good introduction to classical and modern logic. But a pretty dull read.

[Bhakti Hidayat · Rating 5 out of 5]

Perhaps the most recommended intro book for college logic, it's good enough to build a solid foundation on your own. I read it for fun, took me months to finish it, and no, I don't have issues.

It starts small, from analyzing basic arguments; to logical fallacies, and then the basic syllogism, which is easily digestible with tons of quizzes to even sharpen your understanding. The first few chapters are a cakewalk.

Then it comes to symbolic logic, from the basic forms, the usage of the truth table, the basic deduction methods, and the assigning of truth value to disprove an argument; quantified or not, it's all there, and solid enough to cover everything. You will need some other resources online though, as a couple of the concepts can be pretty confusing especially without a tutor to walk you around. And for quizzes, most of the answers aren't available online, therefore I would recommend you self-check them. There is a truth table generator online that you can use, which is the foremost. And there is also a deduction checker of it too online at your disposal, which is crucial in the endgame.

And keep in mind that the book uses the symbol "." instead of an inverted V as the conjugation.