All Commentary
Saturday, August 1, 1970

The Art of Thinking

Man cannot think at all (or only at the level of a chimpanzee) if he did not inherit from the society and civilization in which he was born the priceless gift of an already-created language. Without this he would not only be unable to reason logically, he would have nothing worthy to be called a “concept.” He could not frame a sentence; he could not even name things. We think in words, even in conver­sations. Our language, concepts, and logic are part of the social inheritance of all of us.

This has several important cor­ollaries. One of them is that be­fore the individual can even dream of “thinking for himself,” or solv­ing a simple problem, he must first acquire at least an elementary knowledge of what mankind has already learned, discovered, or in­vented before him. Even if he re­ceives what is called a good modern education, it will take him till the age of eighteen or more to acquire even the rudiments of what he needs to know.

So my new book would empha­size far more than my previous one the need of extensive reading and study before the reader can profitably launch on “thinking for himself” or arriving at “indepen­dent” conclusions. That, of course, should always be his goal; but the road to that goal is long, hard, and often roundabout.

How to Study

My new book would therefore have a chapter on “How to Study.” One of the topics considered in it would be the possibility of increas­ing one’s reading speed, and the methods of achieving this. But my new book would emphasize what some of the teachers of the new “speed reading” methods unfortunately do not—the necessity that the student learn to “change gears,” i.e., to learn to read differ­ent matter at different speeds de­pending on its nature, importance, and difficulty, as well as on the reader’s purpose in reading it.

One of the chief problems of study, in fact, is how often the student should reread a textbook or a particular passage of it, or how often he should go over sub­stantially the same material in other books. In studying a foreign language, for example, the reader may have to come across the same word or phrase again and again before he is able to translate it on sight, and he may have to see or hear it many more times before he can use it unprompted in a sentence framed by himself.

Knowledge of a foreign lan­guage, in short, is not really knowl­edge until it has been thoroughly assimilated, or worked in. This is no doubt widely recognized. But what is much less widely recog­nized is that this is not merely true of a language but of practi­cally any other subject. A doctor is seldom a good doctor when he has just graduated from medical school, even though he may already have been over much verbal ma­terial with dreary repetition. Not until he has served as an intern, or been in private practice a cou­ple of years, and so gone still more over the same ground and again and again encountered the same or similar problems, is he likely to achieve a quick and con­fident recognition and interpre­tation of symptoms.

A student of algebra may be taught how to extract the square root of a polynominal, and may be intelligent enough to follow the demonstration the first time, but it will probably not be until he has extracted many square roots of many polynominals that he will really feel confident he knows how. The student of languages, as well as the student of math, or a doc­tor, or a pianist, soon finds him­self slipping backward if he ceases to study or practice. Our mem­ories are not what they should be. A little of our knowledge is con­stantly oozing away. Knowledge and skill cannot be retained, let alone increased, except by con­stant addition, renewal, and re­freshment.

I might also in this “How to Study” chapter give some hints to the reader on how to set up a study program to teach himself a particular subject, but in this epilogue I am postponing that to a later point. I may say here, how­ever, that there are already some excellent books or pamphlets on how to study. The reader should find a wide range of choice in a college bookshop.


A man with a scant vocabulary will almost certainly be a weak thinker.


Language and Thought

My new book would have a chapter on “Language and Thought.” I pointed out earlier that without language we would hardly be able to think at all. As the great nineteenth century phi­lologist Max Mueller put it: “To think is to speak low. To speak is to think aloud.”

The corollary of this is tremen­dously important. A man with a scant vocabulary will almost cer­tainly be a weak thinker. The richer and more copious one’s vocabulary and the greater one’s awareness of fine distinctions and subtle nuances of meaning, the more fertile and precise is likely to be one’s thinking. Knowledge of things and knowledge of the words for them grow together. If you do not know the words, you can hardly know the thing. We are told that the Tasmanian method of counting is: “One, two, plenty.” This points to a very significant truth. Man could not even count, certainly not beyond the number of fingers on his hands, until he had invented names and symbols for numbers. For in speaking of the need for language for thought, we must, of course, include sym­bols as an integral part of lan­guage. It is amazing how recent in human history are even the Arabic numerals, the denary system, and the elementary signs for addition, subtraction, multiplication, and division—not to speak of the myriad symbols now constantly used in algebra, geometry, trig­onometry, differential and integral calculus, vector analysis, and other branches of higher mathematics. A single tiny symbol or formula—like that for zero, or pi, or a function, or the square root of minus one, or dy/dx, or Einstein’s famous E = mc2 (energy equals the quantity of matter multiplied by the square of the speed of light)—can condense, sum up, fix, and hold forever a discovery that it may have taken mankind centuries to arrive at.

Words Sharpen Observation

A vocabulary increases and sharpens our observation, as sharp observation in turn leads us to increase our vocabulary. The stu­dent of nature who is learning to recognize bushes and trees finds his observation increasingly shar­pened as he is told how to identify respectively an oak, maple, elm, beech, pine, spruce, or hemlock. The name both fastens down the results of observation and tells him what distinguishing traits to look for. As a result of his knowledge, a countryman very seldom calls a specific tree simply a tree. The professional forester or nursery­man habitually makes even finer distinctions, such as that between red oaks, black oaks, and white oaks, or between Norway maples, Schwedler maples, and sugar ma­ples.

Once again, when a student of nature has a leaf described to him, or wants to describe one, he finds himself immeasurably aided by a specialized vocabulary of descrip­tion for certain characteristics of edge or form—dentate, crenate, serrate, ovate, obovate, lanceolate, oblanceolate, sagittate, orbicular, and so on. The more names that are mastered, the more is obser­vation sharpened.

This intimate interdependence of language and thought exists in all fields of knowledge, from the simple and concrete to the most abstruse and abstract.

The highest thrill of the ama­teur bird watcher comes when he identifies a new species for the first time. He usually does this by comparing the new bird he has just seen with the pictures or de­scriptions in a bird book. But to be able to do this he has to ob­serve very sharply everything he can—its size, shape, color, and markings, down to the minutest details, like the color and shape of its bill, its peculiarities of flight and song, and so forth.

When the bird student knows the name of the new species or its verbal description in a book he knows what to look for. His ob­servation becomes keener not only for that time, but for the next time. By this process he finds his observation becoming ever more acute as his knowledge becomes fuller. The professional ornitholo­gist, by a refinement of the same method, knows when he has dis­covered a species hitherto unrec­ognized by anyone. Whereupon he preserves his discovery, and makes it accessible to all, by giving the new species a name, accompanied by a full and precise pictorial and verbal description.

Identifying the Parts

Let us turn to still another field. The first thing the student of medicine is asked to do is to study anatomy. This means, at the be­ginning, to learn to recognize and name the hundreds of parts of the human body, from the anulus in­guinalis profundus to the vesicula seminalis. It requires the dreary memorization of hundreds of names even to master what is called gross anatomy. When the student comes to some special part, like the nervous system (not to mention microscopic anatomy), he must learn hundreds of more names. And he must learn this special vocabulary if for no other reason than to know what his pro­fessors are talking about. Later on, as, say, a medical researcher, he must know this vocabulary not only to explain his findings in a medical journal, but to make them in the first place.

One of the things that used to puzzle me as a youth was why even the greatest painters and sculptors, like Leonardo da Vinci and Michelangelo, thought it nec­essary to study artistic anatomy. Their eyes were sharp enough: couldn’t they have painted just what they saw? The answer, as I have now come to realize, is that by learning the names, position, and description of the muscles, tendons, and veins in the normal human body they knew what to look for and where to look for it, and their naturally acute vision was sharpened still more.

What is true for the supreme genius is true for those of us who are less gifted. In a charming in­troduction to his book on birds, John Kiernan tells the reader that he had never seen a white-breast­ed nuthatch until he saw, on a bird card, a picture of one going down a fence post headfirst. The next day he saw five different nut­hatches at different places. They had always been around, but he had never before looked for them. He had been blind!

The reader has perhaps had the experience of looking at some ob­ject through binoculars or a mag­nifying glass and seeing details that he could not previously see with his naked eye; but on remov­ing the glass he could still see them, because now he knew they were there. The Arabian Nights story, telling how Ali Baba could not open the door to the robbers’ den until he had learned to say “open sesame,” contains a pro­found moral. To be admitted to the realms of knowledge we must learn the right passwords.

Symbols of Communication

I remarked earlier that when I speak of “language” I do not have in mind merely words and sen­tences, but symbols, signs, and signals of all kinds used in human intercommunication. There are special symbols in every science; but I have particularly in mind numbers, notation, and other sym­bols of mathematics by which the results of mathematicians are made known to each other and without which, in fact, the mathematicians themselves could not even think mathematically. One authority, To­bias Dantzig, has written a book called Number: The Language of Science.

There are still further corol­laries to be drawn from the inex­tricable interdependence of thought and language. He who seeks to be a clear and precise thinker must also seek to be a clear and precise writer. Good writing is the twin of good think­ing. He who would learn to think should learn to write.

One of the most important steps, to repeat, is to enlarge one’s vocabulary. The way most often consciously adopted for doing this is to study long lists of assorted words, usually polysyllabic. This may be better than nothing, but it is not the method to be preferred. It is generally more advisable to go from things and concepts to the names for them than to go from miscellaneous names to things and concepts. Vocabularies tend to grow with knowledge in general, and particularly with increasing knowledge of special subjects. Each science, discipline, art, sport, or branch of knowledge has its own special vocabulary, which is acquired with study or experience of that branch of knowledge or activity.

An abundant vocabulary is usu­ally a by-product of wide knowl­edge. One good rule, both in thinking and writing, is never to use a word if you have only a vague and uncertain knowledge of its meaning. Look it up first in the dictionary to find its exact denotations and connotations—not to speak of its correct pronuncia­tion!

Writing Improves Thinking

The reader who seeks to write well and think well should aim first at the essential qualities—coherence, clarity, precision, sim­plicity, and brevity. Euphony and rhythm are of course also desir­able, but they are like the final rubbing on a fine piece of furni­ture—finishing touches justified only if the piece has been soundly made.

As a method of procedure, the apprentice writer may often find it advisable first of all to root out his faults. He should try to ac­quire the Five Virtues of Coher­ence, Clarity, Precision, Simplic­ity, and Brevity by vigilant ab­stention from the Five Vices of Incoherence, Obscurity, Vague­ness, Pedantry, and Circumlocu­tion.

For those who ask why writing is important to the thinker, one reply would be that it may be of crucial importance when the think­er wishes to present the results of his thinking to his professional colleagues or directly to the public. Newton and Leibnitz each invent­ed the calculus independently, and Newton’s discovery was earlier. But it was the calculus as present­ed by Leibnitz that other mathe­maticians began to use, mainly be­cause Leibnitz devised a better no­tation.


He who would learn to think should learn to write.


The Abbe J. G. Mendel’s bio­logical experiments and theories on heredity, propounded in 1866, were of epoch-making importance, comparable to Darwin’s theory of evolution published in The Origin of Species in 1859. Darwin’s book brought him instant world fame, but neither Mendel nor his con­tribution received any recognition until 1900, thirty-four years after he had published his results and sixteen years after his death. Rec­ognition came only when other botanists independently obtained results similar to Mendel’s and in searching the literature found that both the experimental data and the general theory had been published by him a third of a cen­tury before. Mendel’s original pa­per had reached the principal li­braries in Europe and America. But it was so sparely and obscure­ly written that even eminent bot­anists at the time failed to grasp its implications.

A book on the art of thinking is not the place to dwell in detail on the art of writing. The most illu­minating discussion of its length written on the subject is still Her­bert Spencer’s essay on “The Phi­losophy of Style” published in 1871. (Unfortunately, its own style is somewhat stilted and pompous.) A helpful little manual is The Elements of Style by Wil­liam Strunk, Jr., first published in 1918 and then republished with a delightful introduction and added chapter by Strunk’s former stu­dent, E. B. White, in 1959.

Every professional writer ought to have, in addition to at least one good dictionary, four style books in his study: The King’s English, by H. W. Fowler and F. G. Fowler, A Dictionary of Modern English Usage, by H. W. Fowler, Usage and Abusage, by Eric Partridge, and Modern American Usage, by Wilson Follett.

A Notebook or Journal

And every serious thinker, espe­cially if he hopes to be a profes­sional writer, should keep a note­book or a journal. I pointed out, in the first edition of this book, that good ideas are often elusive and must be captured in flight—in other words, that it is excellent practice always to have a pencil and pad handy, so as to jot down a good thought the moment after it lights up your mind. The com­placent assumption that once a bright idea or happy phrase occurs to you it is a permanent acquisi­tion, to be called upon only when needed, too often proves false. Even Nietzsche, one of the great seminal minds of the nineteenth century, found that: “A thought comes when it wishes, not when I wish.”

When we write out our ideas, we are at the same time testing, developing, arranging, crystalliz­ing, and completing them. We imagine ourselves not only making these ideas clear to others, but making them seem as important to others as they do to ourselves. So we try to make what was vague in our minds precise and definite; what was implicit, explicit; what was disconnected, unified; what was fragmentary, whole. We frame a generalization, then try to make it as plausible as we can; we try to think of concrete illustrations of it. And as we do this, we also expose it to ourselves—and some­times, alas, find that it is empty, untenable, or sheer nonsense.

A lot of ideas that cannot be tested by formal experiments can be at least partly tested by writ­ing them out. A great teacher of my acquaintance, when a student bothered him once too often by persisting in some silly proposal of his own on a subject, would suggest that the student write a paper on his idea and bring it in at the next seminar. The student seldom did so; perhaps because he was mentally lazy, but more likely because, when he attempted to write it out and to prove its valid­ity, he found it to be hopelessly vague or a self-contradiction.

Writing Aids Concentration

One incidental advantage of the habit of writing out one’s ideas is that it promotes concentration as almost no other practice does. As one who has written daily news­paper editorials or weekly maga­zine columns for many years, I can testify that nothing forces one to pull one’s thoughts together more than deciding on a topic, sit­ting before the typewriter, feeding in a clean sheet of paper, and then trying to frame one’s exact theme, title, and opening paragraph.

Francis Bacon summed it up with unsurpassable conciseness: “Reading maketh a full man, con­ference a ready man, and writing an exact man.”


Good ideas are elusive and must be captured in flight… jot down a good thought the moment after it lights up your mind.


If the reader wants to know what the best and most stimulat­ing notebooks and journals are like, I suggest, for a starting as­sortment: The Meditations of Marcus Aurelius, Pascal’s Pensées, The Heart of Emerson’s Journals, Samuel Butler’s Note-books, and Charles Horton Cooley’s Life and the Student. All of these, of course, can be sampled rather than read through; they are admirable bedside books.

How to Solve a Problem

In the first edition, I remarked that all thinking is problem-solv­ing. My new book would contain a special chapter on “How to Solve a Problem.”

It would begin, perhaps, by rais­ing the problem: how to recog­nize a problem when you see it. The better informed, more intelli­gent, and more intellectually curi­ous you are, the more problems you will become aware of. In his Voyage of the Beagle, Darwin de­scribes how the savages, at one harbor in which the Beagle an­chored, immensely admired the small boats in which his party landed, but paid no attention whatever to the big ship. They took it for granted, like a fact of na­ture. It was too far out of their experience.

Feebleminded barbarians, no doubt. But most of us civilized laymen daily switch on the lights, or turn on our television set, with­out the slightest curiosity regard­ing the cause of the miraculous result.

A question akin to this, which my chapter would raise, is “What is the problem?” Our modern so­cial reformers are constantly pre­occupied, for example, with the problem of poverty. But poverty is the original condition of man, from which he has sought to es­cape by the sweat of his brow, by work, production, and saving. It was when Adam Smith asked him­self not what causes the poverty but what causes the wealth of na­tions that real progress on the problem began to be made. For centuries, in the same way, doc­tors took health for granted and assumed that the only problem is what causes disease. It was not until surgeons tried to transplant kidneys, hearts, and other organs that they became acutely troubled by the problem of what causes im­munity. There is always the pos­sibility of learning more by ask­ing ourselves the opposite ques­tion. There are hundreds of books on How to Play Chess. Znosko-­Borowsky created a mild sensation by writing one called How Not to Play Chess.

Rules for Discovery

I suspect that my chapter on problem-solving would be heavily obligated to a little book by George Polya, first published in 1945, called How to Solve It.

Polya’s book is devoted primar­ily to the problem of solving prob­lems in mathematics; but it is ap­plicable over the whole field of in­vention, discovery, and independ­ent thinking.

“A great discovery,” the author tells us in the preface, “solves a great problem but there is a grain of discovery in the solution of any problem. Your problem may be modest, but if it challenges your curiosity and brings into play your inventive faculties, and if you solve it by your own means, you may experience the tension and enjoy the triumph of discovery. Such experiences at a susceptible age may create a taste for mental work and leave their imprint on mind and character for a lifetime.”

Polya has all sorts of instruc­tive things to say about what questions to ask—”What is the unknown?”—about the uses of analogy, about “decomposing” and “recomposing” problems, about Descartes’ rules for invention, about the indispensability of good symbols and good notation for mathematical thinking. He tells how, overnight or after a longer interval, our subconscious mind will often solve problems for us, but warns that “conscious effort and tension seem to be necessary to set the subconscious work going”otherwise everything would be too easy.

Polya calls his whole book an effort to teach Heuristic: “The aim of heuristic is to study the methods and rules of discovery and invention…. The most fa­mous attempts to build up a sys­tem of heuristic are due, to Des­cartes and to Leibnitz, both great mathematicians and philosophers.”

Polya’s own illustrations and ap­plication are confined entirely to mathematics, for which his own enthusiasm is contagious. The reader, he says, should at least try to find out whether he has a taste for mathematics, and he may find out that “a mathematics problem may be as much fun as a crossword puzzle, or that vigorous mental work may be an exercise as desirable as a fast game of tennis. Having tasted the pleasure in mathematics he will not forget it easily and then there is a good chance that mathematics will be­come something for him: a hobby, or a tool of his profession, or his profession, or a great ambition.”


Conscious effort and tension seem to be necessary to set the subconscious work going.          —Polya


Specialization, Perseverance, Analogy

My new book would contain a chapter on “The Dilemma of Spe­cialization.” The dilemma is this. In the modern world knowledge has been growing so fast and so enormously, in almost every field, that the probabilities are immense­ly against anybody, no matter how innately clever, being able to make a contribution in any one field unless he devotes all his time to it for years. If he tries to be the Rounded Universal Man, like Leonardo da Vinci, or to take all knowledge for his province, like Francis Bacon, he is most likely to become a mere dilettante and dabbler. But if he becomes too specialized, he is apt to become narrow and lopsided, ignorant on every subject but his own, and perhaps dull and sterile even on that because he lacks perspective and vision and has missed the cross-fertilization of ideas that can come from knowing something of other subjects.

I do not know the way out of this dilemma, or the exact com­promise, but I hope to find it by the time I write my new book.

My new book, like the present one, will have a chapter on con­centration, but it is more likely to be called “Concentration and Per­severance,” for it will put far more emphasis on patience, plod­ding, perspiration, pertinacity, determination, effort, work—on again and again returning to an obstinate problem until it is solved. Scientists talk much nowadays of “serendipity”—the fac­ulty of making desirable discover­eries by accident. An example often cited is how Sir Alexander Fleming discovered penicillin be­cause one of his laboratory techni­cians had carelessly left the top off a dish in which a virulent in­fectious organism, staphylococcus, was growing; a number of fungi had floated into the open dish, overgrown the bacteria—and killed it. The accident led Fleming to his discovery. But these “acci­dents” only seem to bear fruit when they happen to alert inde­fatigable scientists who have already been working for years on a project. As Pasteur put it: “Chance favors the prepared mind.”

In my new book I would treat Analogy less cavalierly than I did earlier in this one, and perhaps have a separate chapter with that title. I did mention analogy in my first edition as a constructive method of making discoveries, but then went on to talk almost exclu­sively about its dangers and pit­falls. A. Wolf, in his Textbook of Logic (1938), emphasizes its achievements:

“One need only think of the most important discoveries in the history of science, in order to re­alize the enormous value of anal­ogy. Our conception of the solar system (the helio-centric theory) owes a great deal to the analogy of the miniature system of Jupiter and the Medicean satellites. Some of the most important discoveries in modern mathematics are due to the analogy, discovered by Des­cartes, between algebra and geometry. The wave-theory of sound was suggested by the observation of water-waves; and the undula­tory theory of light was suggested by the analogous air-waves which transmit sound. The theory of natural selection by the struggle for existence was suggested to Darwin by his knowledge of the artificial selection by which breed­ers have produced the many varie­ties of domestic animals. And so forth.”

Like the first edition of the present volume, my new book would contain chapters on “Sub­jects Worth Thinking About” and on “Books on Thinking.”

Subjects Worth Thinking About

But the former chapter, instead of containing a list of important but very miscellaneous problems, would call the reader’s attention to some of the innumerable sciences or disciplines in which he could en­joyably and profitably interest himself—agriculture, astronomy, atomic physics, biology, building, chemistry, crystallography, electricity, engineering, fossils, gar­dening, geography, geology, math­ematics, medicine, metallurgy, me­teorology, minerology, pathology, physics, physiology, and zoology. These are all physical sciences. I name so many here because my first edition rather neglected them in its emphasis on social questions. But, of course, in my new book the reader would still be invited to consider the attractions of the social disciplines—political sci­ence, jurisprudence, economics, ethics, psychology, anthropology, or archeology.


I cannot share the snobbery of those who seem able to express their esteem of pure science only by disparaging its practical applications.


In choosing subjects to think about or problems to solve, I must confess a personal preference for those that are useful. I admire disinterested curiosity and the achievements of “pure” science and “pure” research as much as anyone; but I cannot share the snobbery of those who seem able to express their esteem of pure science only by disparaging its practical applications. Both are admirable; and they are mutually dependent. The partisans of pure science chronically talk as if there were only a one-way dependency, and as if inventors were men of a lower order than pure scientists. They never tire of reminding us how the inventions of Marconi in wireless telegraphy and de Forest in radio were dependent on the previous theoretical discoveries of Clerk Maxwell and Hertz. All very true. But how far would pure re­search have been able to go in a hundred fields if it had not been for the invention, say, of the mi­croscope? Or, for that matter, of the printing press?

As Karl R. Popper has pointed out, in his Poverty of Historicism (1957), one need not espouse a narrow pragmatism in order to ap­preciate Kant’s saying: “To yield to every whim of curiosity, and to allow our passion for inquiry to be restrained by nothing but the limits of our ability, this shows an eagerness of mind not unbe­coming to scholarship. But it is wisdom that has the merit of se­lecting, from among the innumer­able problems which present them­selves, those whose solution is important to mankind.”

The Study of Economics

The reader of my new book would receive some guidance in how to take up a subject new to him, and there would be some specific illustrations. Suppose, for example, that he wanted to take up economics in a systematic way. He would be advised to begin with some short elementary text. An excellent one for the beginner to­day would be, say, Essentials of Economics, a book of only one-hundred pages by Faustino Ballvé (Irvington-on-Hudson, N. Y.: Foundation for Economic Educa­tion). A collection of essays, Plan­ning for Freedom, by Ludwig von Mises, is less systematic but enor­mously stimulating. (I would be less than mercenary if I failed to mention here also my own Econ­omics in One Lesson, available both in hard-cover by Harper & Row and in paperback by Mac­fadden-Bartell.)

The next step would be to read a book of intermediate length. One of the best is A Humane Economy by the late Wilhelm Roepke (Reg­nery).

The student would now be ready to tackle one of the most compre­hensive and advanced books on the subject, of which I will mention only three. Human Action: A Treatise on Economics by Ludwig von Mises (Regnery, 907 pages) extends the logical unity and pre­cision of economics beyond any other work. Some readers seem to find this excessively difficult. For these I can strongly recommend Man, Economy, and State, by Murray N. Rothbard (D. Van Nostrand, two volumes, 987 pages) which is equally comprehensive, and along Misesian lines, but in which the reader may find the ar­rangement and exposition easier to follow. Finally, I would include in this triad an older book, Philip Wicksteed’s The Common Sense of Political Economy (1910, new edi­tion 1933, two volumes, 871 pages), as remarkable for the ease and lucidity of its style as for the penetration and power of its reasoning.

When the reader has finished even one of the books in this ad­vanced triad, perhaps after a couple of introductory volumes, he will be prepared to choose his own further reading in economics, and may browse among the great writ­ers and thinkers who created the science—Hume, Adam Smith, Ricardo, Mill, Jevons, Menger, Boehm-Bawerk, Wicksell, Mar­shall, John Bates Clark—an en­viable feast. Adam Smith’s Wealth of Nations, though published in 1776, can still be ardently recommended no less for its literary se­ductiveness than for the brilliant light it still can throw even on the economic life of today.

General Rules for Exploring Any New or Strange Subject

Of course, my book could only include such specific recommenda­tions on one or two subjects. For others there would have to be gen­eral rules. One would be to ask an expert in the subject. Another would be to consult the article on the subject in an encyclopedia and to see whether that included, as it ought to, a good list of references. A third rule would be to consult such a book as Good Reading, a paperback published by The New American Library. This is a vol­ume sponsored by the College Eng­lish Association and prepared by the Committee on College Read­ing. I happen to have the nine­teenth printing which came out in 1964, but revisions have been ap­pearing every year or two. The volume lists selected books on ev­ery conceivable subject—history, fiction, poetry, drama, biography, essays, philosophy, religion, and all the leading arts and sciences. There is also an instructive list of “100 Significant Books.”

One last general piece of advice. No practice excels that of brows­ing along a library shelf contain­ing books on the subject that has awakened your interest, and sam­pling them.

If I may be permitted a per­sonal note, it seems to me, looking back, that the hours of purest happiness in my own youth were spent in just this way. I would avidly sample one book after an­other, and when the bell rang, and the library closed for the night, and I was forced to leave, I would leave in a state of mental intoxi­cation, with my new-found knowl­edge and ideas whirling in my head. I would speculate eagerly on what solutions the authors I had read had come to in the passages I hadn’t had time to finish. I think now that these unpremedi­tated efforts to anticipate an au­thor’s conclusions stimulated my thinking far more than any con­tinuous uninterrupted reading would have done. In fact, when I came back to one of these same books the next evening, I most often felt let down. The night be­fore, the author had seemed on the verge of some marvelous breakthrough, opening new vistas to the soul, and now he seemed to fizzle out in a truism.

Books on Thinking

The final chapter in my new book, like the final chapter in the first edition of this one, would be about “Books on Thinking.”

My new references would sup­plement, rather than displace, those in my first edition. For ex­ample, I cited there only two “classics” on the art of thinking—John Locke’s Conduct of the Un­derstanding, and Arthur Schopen­hauer’s Thinking for Oneself. I should also have included the three classics mentioned in my present preface: Bacon’s Novum Organum, Descartes’ Rules for the Di­rection of the Mind, and Spinoza’s Improvement of the Understand­ing.

My new bibliography would of course also include a handful of good books written specifically on the art of thinking since the orig­inal edition of Thinking as a Sci­ence appeared. One of these would surely be The Art of Thought, by Graham Wallace (1926). Another would be Thinking to Some Pur­pose, by the late British logician L. Susan Stebbing. Her chief em­phasis is on how to detect illogi­calities in other people’s thinking and how to avoid them in our own.

In addition, my new bibliog­raphy would refer the reader to passages, paragraphs, and even single sentences, widely scattered through the works of many authors, that throw light on the art of thinking. Some of these can be found in the biographies or auto­biographies of great thinkers. My first edition cited material of this nature from the autobiographies of John Stuart Mill and Herbert Spencer. But there are illuminat­ing passages in many writers less well known.

I quote here a few lines, for ex­ample, from Charles Horton Cool­ey’s admirable notebook, Life and the Student (1927):

“Let our struggle be with facts, with life, rather than with other writers. We cannot have the spirit of truth and the spirit of contro­versy at the same time.

“A writer whose aim is to be unlike others is liable to a sub­servience of contradiction. That is, he after all gets his cue from them, takes the other end of the same rope. Originality raises new questions.”

Though it starts apparently in contradiction, the advice of Morris R. Cohen in the preface to his Reason and Nature (1931) rein­forces that of Cooley:

“The philosopher whose primary interest is to attain as much truth as possible must put aside as a snare the effort at originality. In­deed, it seems to me that the mod­ern penchant for novelty in philos­ophy is symptomatic of restless­ness or low intellectual vitality….

The principle of polarity calls at­tention to the fact that the tradi­tional dilemmas, on which people have for a long time taken oppo­site stands, generally rest on dif­ficulties rather than real contra­dictions, and that positive gains in philosophy can be made not by simply trying to prove that one side or the other is the truth, but by trying to get at the difficulty and determining in what respect and to what extent each side is justified. This may deprive our results of sweep and popular glamour, but will achieve the more permanent satisfaction of truth.”

Lessons in Logic

The art of thinking, like engi­neering or medicine, is based on several distinct sciences. One of these is psychology. I referred in the first edition of this book to John Dewey’s How We Think, which is still useful. But great experimental as well as theoretical progress has been made since Dewey’s book was published. The reader could bring himself abreast of this by consulting the article on Thinking and Problem Solving, Psychology of in the 1965 edition of the Encyclopedia Britannica.

The article itself includes an ex­tensive list of books for further reading.


We cannot have the spirit of truth and the spirit of con­troversy at the same time.          —Cooley


Logic, the study of the general conditions of valid inference, is of course the chief established sci­ence on which the art of thinking must be based. My recommenda­tion for initial reading in my first edition was Stanley Jevons’ Ele­mentary Lessons in Logic. Because Jevons was an excellent writer as well as a first-rate thinker, this can still be read with pleasure and profit. But today I would prefer to recommend as an introductory volume A. Wolf’s Textbook of Logic (first edition 1930, but often republished). More advanced, but still not too difficult, is L. Susan Stebbing’s Modern Introduction to Logic (1940). Still more advanced, longer, and more difficult is An Introduction to Logic and Scien­tific Method, by Morris R. Cohen and Ernest Nagel (1934).

Scientific method is closely con­nected with logic. In fact, it is usual for modern books on logic (and this is true of the three just mentioned—the last explicitly in its title) to treat traditional logic in the first half of the book as “formal” or “deductive” logic, and then to devote the second half to “inductive” logic and to “scien­tific method” in general. This sec­ond subject includes discussions of such subjects as circumstantial evidence, the evolutionary and comparative methods, the simpler inductive methods (Mill’s “five canons”), the statistical method, the deductive-inductive method, probability, laws of nature, scien­tific explanation, and so on. Long established as a standard work in this field is F. W. Westaway’s Scientific Method (1919), but the literature is now very extensive.

A brilliant and penetrating book, for those who have the

  • Henry Hazlitt (1894-1993) was the great economic journalist of the 20th century. He is the author of Economics in One Lesson among 20 other books. See his complete bibliography. He was chief editorial writer for the New York Times, and wrote weekly for Newsweek. He served in an editorial capacity at The Freeman and was a board member of the Foundation for Economic Education.