Dear Dr. Adler,

Is there such a thing as knowledge, or is everything a matter of opinion? Our picture of the world and our way of life has changed so much in the last fifty years that I wonder whether we can have certain knowledge about anything. Isn't most of our so-called knowledge really opinion?

Frank Sutton - Kansas City, KS

Most of us know what an opinion is. We recognize that our opinions are beliefs that others need not share. We are used to having those who disagree with us say, "Well, that is only your opinion" (or "your opinion"). Even when we advance an opinion on very good grounds, we usually feel some doubt about it. "I have good reason to believe so," we say, "but I wouldn't swear to it."

Here, then, are three characteristics of opinions: (1) they express probabilities rather than certainties; (2) they are subject to doubt; and (3) reasonable men can differ about which of two conflicting opinions is sounder.

There is a perennial skepticism which holds that everything is a matter of opinion. The extreme skeptic reduces even such things as mathematics and science to opinion. He points out, for example, that a system of geometry rests on arbitrary assumptions. Other assumptions can be made and other systems of geometry developed. Experimental science at it's best, the skeptic maintains, consists of highly probable generalizations, not indubitable certainties.

In contrast with such skepticism is the view of the ancient Greek philosophers. Plato and Aristotle think that there are some matters about which men can have genuine knowledge. In the very nature of things, some things are necessary and cannot be otherwise. For example, by the very nature of wholes and parts, it is necessary that the whole should always be greater than any of its parts. This is something we know for certain. On the other hand, there is nothing in the natures of gentlemen and blondes that makes it necessary for gentlemen always to prefer blondes, and so this is only a matter of opinion.

The difference between knowledge and opinion can also be expressed in psychological terms. When we are asked, "Do gentlemen prefer blondes?" or "Will the Republicans win the 2000 election?", we must make up our own mind. Nothing about the matter in question compels us to answer Yes or No. But when we are asked whether the whole is greater than any of its parts, we have no choice about the answer. If we put our mind to thinking about the relation of whole and part, we can think about the relation in only one way. The object we are thinking about makes up our mind for us.

This gives us a very clear criterion for telling whether what we assert is knowledge or opinion. It is knowledge when the object that we are thinking about compels us to think of it in a certain way. What we think then is not our personal opinion. But when the object of our thought leaves us free to make up our mind about it, one way or the other, then what we think is only an opinion -- our personal opinion, voluntarily formed. Here other rational persons can differ with us.

On this understanding of the difference between knowledge and opinion, we must admit that most of our assertions are opinion. But we should also realize that opinions differ in their soundness. Some are based on considerable evidence or reasons which, while not conclusive, make them highly probable. Others are ill-founded, and others have no foundation at all but are simply willful prejudices on our part.

This leaves open the question whether history, mathematics, experimental science, and speculative philosophy should be classified as knowledge or opinion. As we have seen, the extreme skeptic would say that they are all opinion, though he might recognize that they have much more weight than mere personal opinions or private prejudices. The opposite view, which I would defend, is that we can have knowledge in the fields of mathematics and philosophy, and highly probable opinion in the fields of experimental science and history.

SPEAKING OF OPINION

Visit The New York Times on the Web:

FYI - They have combined their Editorial and Op-Ed sections into one new section, Opinion, with easy access to editorials, columns, letters, cartoons and forums.

http://www.nytimes.com/opinion

HELP FOR AGING EYES

Dear Max,

Having "aging eyes" I must rely on talking books, so it is encouraging to see you formatting Dr. Adler's writings in audio format. I have been relying on existing lists from talking book publishers, and will continue to do so if rentals are available, but I will check with you when such is not the case.

By the way, Cassette format is proving to be ideal in the fast read of the entire book Dr. Adler advocates in this posting, especially if you have a variable speed player as I do. If the material is familiar I crank up the pace. If not I can slow it down or repeat it with ease.

Greetings of the season to all,

Dr. Gerald Foster - Denver, CO

GREAT IDEAS FOR HOLIDAY GIVING

THE DICK CAVETT SHOW (1978)

Dick Cavett conducts a wonderfully entertaining interview with Mortimer Adler on his youth, his career, philosophy, and "Great Treasury of Western Thought." Edifying and lot's of laughs.

(Two half-hour shows) $ 35.00

A POIGNANT NOTE FROM BILL MOYERS

. . . I could fill a book with examples. One of my favorites happened some years ago after you had broadcast a special I did with Mortimer Adler, the educator and philosopher whose lifelong passion has been to awaken students of any age -- 16 or 60 -- to the power of critical thinking. In the two weeks after our program on his book "Aristotle for Everybody," over 12,000 people wrote for the transcript.

But the real payoff came in Penn Station a few weeks later. I was traveling with CBS friends who were skeptical when I told them what the response to the series had been. We were waiting for the train and a fellow, rather shabbily-dressed approached us. I thought he was a panhandler looking for a handout. He held his hand out, all right -- only to take mine in it, and shake it vigorously. He said, "Mr. Moyers, I want to thank public television for introducing me to Mortimer Adler and Aristotle, with them as friends I'm a very rich man."

Bill Moyers

Adler on Aristotle (1979) Bill Moyers with Mortimer Adler at Aspen (One-hour cassette) $35.00

ARISTOTLE'S "ETHICS" - The Theory of Happiness. Encyclopaedia Britannica's Classical Greece - Lesson 3 Written and presented by Mortimer Adler, this is an invaluable addition to your library and an ideal program for students and children. (30 minutes in color, with animation and music) $30.00

PLATO'S "APOLOGY" Encyclopaedia Britannica's Classical Greece - Lesson 2 Written and presented by Mortimer Adler, this is an invaluable addition to your library and an ideal program for students and children. (30 minutes in color, with animation and music) $30.00

GREAT BOOKS OF THE WESTERN WORLD Very rare footage of Robert M. Hutchins and Mortimer J. Adler introducing and explaining the development of the Syntopicon and Britannica set of Great Books of the Western World. (1952) (30 minutes) $30.00

TEST YOUR GENERAL KNOWLEDGE *

1) List in the proper order the three longest rivers in North America?
2) What do the following have in common: crayfish, cuttlefish, jellyfish, shellfish, silverfish, starfish?
3) Who said, "Never take money for work you would not do if you did not need the money"?
4) Which of the 48 contiguous United States is Northern most?
5) Name the British statesman who said, "There are three kinds of lies: lies, damned lies, and statistics"?

* Each month, the first member to send in the correct answers to our quiz, will receive an autographed copy of Dr. Adler's latest book, "Adler's Philosophical Dictionary: 125 Key Terms for the Philosopher's Lexicon."

ANSWERS TO LAST MONTHS QUIZ

1) 116 years, from 1337 to 1453.
2) Ecuador.
3) From sheep and horses.
4) November. The Russian calendar was 13 days behind ours.
5) Squirrel fur.
6) The Latin name was Insularia Canaria --Island of the Dogs.
7) Albert. When he came to the throne in 1936 he respected the wish of Queen Victoria that no future king should ever be called Albert.
8) Distinctively crimson.
9) New Zealand.
10) Thirty years, of course. From 1618 to 1648.

We reserve the right to edit all submissions for relevancy and concision and to publish them at our discretion.

The Great Ideas Online is published free of charge to its members by the Center.

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