This is part of my book summary collection which includes The Essays of Warren Buffett, Poor Charlie's Almanack, Special Operations Mental Toughness, and 50+ more. Browse them all to find the best ideas from history's greatest books →

Book Summary

This is my book summary of A Few Lessons From Sherlock Holmes by Peter Bevelin. My notes are informal and often contain quotes from the book as well as my own thoughts. This summary also includes key lessons and important passages from the book.

• Overview
• The Book in Three Sentences
• Sherlock Holmes and Dr. Joseph Bell
• Some Lessons from Sherlock Holmes
• How to Solve a Case
• Step One: Observation
• The Difference Between Seeing and Observing
• Step Two: Deduction
• Step Three: Test Your Theory
• Some Other Tools
• More Books Like This
• Buy the Book

Overview

Peter Bevelin‘s first book, Seeking Wisdom from Darwin to Munger, is one of the best books you’ve probably never heard of. He’s just released another book, A Few Lessons From Sherlock Holmes, aimed at those who want to improve their thinking.

“Peter Bevelin is one of the wisest people on the planet.” — Nassim Taleb

I’m a big fan of Sherlock Holmes, and Peter is not the first person to explore the wisdom that can be drawn. Maria Konnikova’s book, Mastermind: How To Think Like Sherlock Holmes, takes a deep look at Sherlock Holmes’s methodology to develop the habits of mind that will allow us to mindfully engage the world.

Peter’s book is shorter than Maria’s and encourages you to draw your own conclusions. A Few Lessons From Sherlock Holmes is a book for those who want to improve their thinking. Peter Bevelin has distilled Arthur Conan Doyle’s Sherlock Holmes into bite-sized principles and key quotes. It contains useful and timeless methods and questions applicable to a variety of important issues in life and business.

This book will appeal to both Sherlock fans as well as those who want to think better. It contains useful and timeless methods and questions applicable to a variety of important issues in life and business. We could all benefit from a few lessons from Sherlock Holmes.

Let’s look at some of the lessons Bevelin brings to our attention.

“What distinguishes Holmes from most mortals,” Bevelin writes, “is that he knows where to look and what questions to ask. He pays attention to the important things, and he knows where to find them.”

The Book in Three Sentences

The character of Sherlock Holmes was actually inspired by a medical professor that Arthur Conan Doyle studied under at Edinburgh University called Dr. Joe Bell. Sherlock Holmes is above all else a thorough, first principles, your theory must fit the facts thinker. He works logically starting first by observing (not merely seeing), then making deductions from those facts, to arrive at a theory (or a few) that you then test against new facts to arrive at the inevitable truth.

Sherlock Holmes and Dr. Joseph Bell

I had no idea, but Sherlock Holmes wasn’t a work of fantasy or fiction. He was inspired by Dr. Joseph Bell, who Arthur Conan Doyle studied under as Edinburgh University.

“The most notable of characters whom I met was one Joseph Bell, surgeon at the Edinburgh Infirmary. Bell was a very remarkable man in body and mind… He was a very skillful surgeon, but his strong point was diagnosis, not only of disease, but of occupation and character… I had ample chance of studying his methods…. It is no wonder that after the study of such character I used and amplified his methods when later in life I tried to build up a scientific detective who solved cases on his own merits and not through the folly of the criminal.” — A.C. Doyle, Memories and Adventures

‍“Sherlock Holmes is the literary embodiment, if I may so express it, of my memory of a professor of medicine at Edinburgh University.” — A.C. Doyle, Teller of Tales

‍Dr. Joseph Bell wrote of Arthur Conan Doyle: “I always regarded him as one of the best students I ever had. He was exceedingly interested always upon anything connected with diagnosis, and was never tired of trying to discover all those little details which one looks for. — Dr. Joseph Bell, Joseph Bell: An Appreciation by an Old Friend

As such, Dr. Joseph Bell’s philosophies and approach to his work shaped much of Sherlock Holmes and his approached to solving what often looks like unsolvable crimes.

“The experienced physician and the trained surgeon every day, in their examinations of the humblest patient, have to go through a similar process of reasoning, quick or slow according to the personal equations of each, almost automatic in the experienced man, laboured and often erratic in the tyro, yet requiring just the same simple requisites, sense to notice facts, and education and intelligence to apply them.” — Dr. Joseph Bell, The Bookman

‍“Dr. Conan Doyle’s education as a student of medicine taught him how to observe, and his practice, both as a general practitioner and a specialist, has been a splendid training for a man such as he is, gifted with eyes, memory, and imagination. Eyes and ears which can see and hear, memory to record at once and to recall at pleasure the impressions of the sense, and an imagination capable of weaving a theory or piecing together a broken chain or unraveling a tangled clue, such as implements of his trade to a successful diagnostician.” — Dr. Joseph Bell, The Bookman

Some Lessons from Sherlock Holmes

What distinguishes Holmes from most mortals is that he knows where to look and what questions to ask. He pays attention to the important things and he knows where to find them.

“Like the scientist trying to solve a mystery of nature, Holmes first gathered all of the evidence that was relevant to his problem. At times, he performed experiments to obtain fresh data. He then surveyed the total evidence in the light of his vast knowledge of crime, and sciences related to crime, to arrive at the most probable hypothesis. Deductions were made from the hypothesis. Then the theory was further tested against new evidence, revised if need be, until finally the truth emerged with a probability close to certainty.” — Martin Gardner, Mathematics and science writer

To know what to do and not do, we first need some genuine understanding of reality—how things and people are, and what works and what doesn’t work.

Considering many ideas over a wide range of disciplines give us perspective and help us consider the big picture or many aspects of an issue

“Breadth of view… is one of the essentials of our profession. The interplay of ideas and the oblique uses of knowledge are often of extraordinary interest.” — Sherlock Holmes, The Valley of Fear

‍“One’s ideas must be as broad as nature if they are to interpret nature.” — Sherlock Holmes, A Study in Scarlet

‍“Our divisions into sciences are not part of nature… in nature there is really neither chemistry nor physics, nor zoology, nor physiology, not pathology. There are only bodies to be classified or phenomena to be known or mastered.” — Claude Bernard

“I consider that a man’s brain originally is like a little empty attic, and you have to stock it with such furniture as you choose. A fool takes in all the lumber of every sort he comes across, so that the knowledge which might be useful to him gets crowded out, or at best is jumbled up with a lot of other things so that he has a difficult time laying his hands upon it.” — Sherlock Holmes, A Study in Scarlet

‍“Now the skillful workman is very careful indeed as to what he takes into his brain-attic. He will have nothing but the tools which may help him in doing his work, but of these he has a large assortment, and all in the most perfect order. It is a mistake to think that that little room has elastic walls and can distend to any extent. Depend upon it there comes a time when for every addition of knowledge you forget something, therefore, not to have useless facts elbowing out the useful ones.” — Sherlock Holmes, A Study in Scarlet\

‍It is useful to know something about human nature and what motivates people. When in doubt ask, “What is in their interest to do?”

“Well, yes, of course the pay is good—too good. That is what makes me uneasy. Why should they give you 120 per year, when they could have their pick for 40? There must be some strong reason behind it.” — Sherlock Holmes, The Adventure of the Copper Beeches

‍“He remarks that, while the individual man is an insoluble puzzle, in the aggregate he becomes a mathematical certainty. You can, for example, never foretell what any one man will do, but you can say with precision what an average number will be up to. Individuals vary, but percentages remain constant. So says the statistician.” — Sherlock Holmes, The Sign of Four

‍Knowledge doesn’t automatically make us wise. The most learned are often not the wisest.

“Judgement can do without knowledge, but not knowledge without judgement.” — Montaigne

“My simple art… is but systematized common sense.” — Sherlock Holmes, The Blanched Soldier

‍Practice is a good teacher. It teaches us where to look and what to look for.

“Like all other arts, the Science of Deduction and Analysis is one which can only be acquired by long and patient study. Nor is life long enough to allow any mortal to attain the highest possible perfection in it.” — Sherlock Holmes, A Study in Scarlet

‍“Education never ends, Watson. It is a series of lessons with the greatest for the last.” — Sherlock Holmes, The Red Circle

How to Solve a Case

"It does certainly look like a hopeless case… and I see no way out of it at present. But I make it a rule, in all cases, to proceed on the strictly classical lines of inductive inquiry—collect facts, make hypotheses, test them and seek for verification. And I always endeavour to keep a perfectly open mind." — Dr. Thorndyke, The Red Thumb Mark

‍“It it very evident that in this we have two main processes to bear in mind and keep strictly distinct. First, the collection of observations. And second, the inferences to be drawn from them.” — Thomas McCrae, The Method of Zading

‍“Keeping these separate is essential to any orderly solution of our daily problems. But how difficult this is for the majority of us is brought home to every teacher. Take a group of students who are working at physical diagnosis and it is a constant struggle to keep them making observations and not giving inferences—usually from insufficient observations, if from any at all.” — Thomas McCrae, The Method of Zading

‍“To observe correctly and decide wrongly is sure to happen to the best of us. But to observe carelessly happens only when we permit it.” — Thomas McCrae, The Method of Zading

‍“Sherlock Holmes smallest actions were all directed toward some definite and practical end.” — Dr. Watson, A Study in Scarlet

‍See things for what they are: “The greatest sign of an ill-regulated mind is to believe things because you wish them to be so.” — Louis Pasteur

“We approached the case… with an absolutely blank mind, which is always an advantage. We had formed no theories. We were there simply to observe and to draw inferences from our observations.” — Sherlock Holmes, The Cardboard Box

‍“The fatal mistake which the ordinary policeman makes is this, that he gets his theory first and then makes the facts fit in. Instead of getting his facts first and not making all his little observations and deductions until he is driven irresistibly by them into an elucidation in a direction he may never have originally contemplated.” — Dr. Joseph Bell, Dr. Joe Bell

‍“I make a point of never having any prejudices and of following docilely wherever fact may lead me.” — Sherlock Holmes, The Reigate Squire

Step One: Observation

Start with collecting facts and follow them where they lead.

"More is missed by not looking than not knowing." — Thomas McCrae, Medical School Axiom

“For one mistake made for not knowing, ten mistakes are made for not looking.” — James Alexander Lindsay

“It is evident that if the first stage—the collection of facts—is improperly done, we have not the basis for the second and it it bound to be wrong. The game is hopelessly lost from the start. How important, therefore, to give every effort to the collection of our facts.” — Thomas McCrae, The Method of Zading

‍The professor and philosopher Karl Popper often started his lectures telling his audience: “Observe! But we can’t—we need to know ‘Observe what?’” We can’t observe without an idea of what we are looking for. But we should try to gather facts as open-minded and unbiased as possible.

“To experiment without a preconceived idea is to wonder aimlessly.” — Claude Bernard

“One forms provisional theories and waits for time or fuller knowledge to explore them.” — Sherlock Holmes, The Sussex Vampire

‍“Nothing can be done without preconceived ideas, only there must be the wisdom to accept their deductions beyond what experiments confirm.” — Louis Pasteur

“What are the facts? Holmes first gathered enough evidence—both positive and negative—that was relevant to his problem. Data! Data! Data! I can’t make bricks without clay.” — Sherlock Holmes, The Copper Beeches

‍“The temptation to form premature theories upon insufficient data is the bane of our profession.” — Sherlock Holmes, The Valley of Fear

‍Someone once said of Sherlock Holmes, “You’re like a surgeon who wants every symptom before he can give his diagnosis.” His response, “Exactly. That expresses it.” — Sherlock Holmes, Thor Bridge

‍“The principal difference between a good and a bad diagnostician is usually a matter of thoroughness and method. Brains count, of course, but the man who has not collected his facts has but little chance to use his brains.” — Thomas McCrae, The Method of Zadig

‍“If falsehood, like truth, had only one face, we would be in better shape. For we would take as certain the opposite of what the liar said. But the reverse of truth has a hundred thousand shapes and a limitless field.” — Montaigne

“Observe that rule laid down by Chilo: Nothing to excess. Not to believe to rashly, not to disbelieve too easily.” — Montaigne

“We must look for consistency. Where there is a want of it we must suspect deception.” — Sherlock Holmes, Thor Bridge

‍Your primary task as a detection early on is to separate the relevant and important facts from the unimportant and incidental ones.

“The first thing was to look at the facts and separate what was certain from what was conjecture.” — A.C. Doyle, Memories and Adventures

‍“Before we start to investigate that, let us try to realize what we know, so as to make the most of it and to separate the essential from the accidental.” — Sherlock Holmes, The Priory School

‍“Circumstantial evidence is occasionally very convincing, as when you find a trout in the milk.” — Sherlock Holmes, The Noble Bachelor

‍“Circumstantial evidence is a very tricky thing. It may seem to point very straight to one thing, but if you shift your own point of view a little, you may find it pointing in an equally uncompromising manner to something entirely different.” — Sherlock Holmes, The Boscombe Valley Mystery

‍More information isn’t necessarily better. Because having more information tends to falsely increase our confidence.

“A wise man sees as much as he ought, not as much as he can.” — Montaigne

“The world is full of obvious things which nobody by any chance ever observes.” — Sherlock Holmes, The Hound of Baskervilles

‍The eye sees only what it is trained to see: “In the last analysis, we see only what we are ready to see, what we have been taught to see. We eliminate and ignore everything that is not a part of our prejudices.” — Jean-Martin Charcot

“I see no more than you, but I have trained myself to notice what I see.” — Sherlock Holmes, The Blanched Soldier

“Louis [Pierre Charles Alexandre Louis] introduced what is known as the Numerical Method, a plan which we use every day, though the phrase is not now very often on our lips. The guiding motto of his life was ‘Arsmedicatota in observationibus’, in carefully analysing them. To get an accurate knowledge of any disease it is necessary to study a large series of cases and to go into all the particulars—the conditions under which it is met, the subjects specially liable, the various symptoms, the pathological changes, the effects of drugs. This method, so simple, so self-evident, we owe largely to Louis.” — William Osler

“‘Strive to be one of those upon whom nothing is lost,’ said a wise teacher.” — Thomas McCrae, The Method of Zadig

‍Checklist routines for critical factors help—assuming I am competent enough to decide what factors are critical and that I can evaluate them.

“The student or practitioner is more or less possible for us all. It is only by adhering rigidly to a definite routine with patient after patient and day after day that a proper reflex can be obtained.” — Thomas McCrae, The Method of Zadig

‍“The smallest point may be the most essential.” — Sherlock Holmes, The Red Circle

‍“You have an extraordinary genius for minutiae.” I remarked. “I appreciate their importance.” — Sherlock Holmes, The Sign of the Four

‍“It has long been an axiom of mine that the little things are infinitely the most important.” — Sherlock Holmes, A Case of Identity

‍“I always impressed over and over again upon all my scholars—Conan Doyle among them—the vast importance of little distinctions, the endless significance of trifles.” — Dr. Joseph Bell, Joseph Bell: An Appreciation by an Old Friend

‍“The great majority of people, of incidents, and of cases resemble each other in the main and larger features. Most men have a head, two arms, a nose, a mouth, and a certain number of teeth. It is the little differences, themselves trifles, such as the droop of an eyelid, or what not, which differentiates man.” — Dr. Joseph Bell, Dr. Joe Bell

‍What we see is all we think is there. What often leads us astray in an investigation is that we adopt the theory which is most likely to account for the “visible” and found facts. But what if the important is left out? What if it is not reported, withheld, or hidden?

The Difference Between Seeing and Observing

This wonderful dialogue between Sherlock Holmes and Dr. Watson from A Scandal in Bohemia makes clear the difference between simply seeing something and observing it.

“You see, but you often do not observe. The distinction is clear. For example, you have frequently seen the steps which lead up from the hall to this room.” (Holmes)

“Frequently." (Watson)

“How often?” (Holmes)

“Well, some hundreds of times.” (Watson)

“Then how many are there?” (Holmes)

“How many! I don’t know." (Watson)

“Quite so! You have not observed. And yet you have seen. That is just my point. Now, I know that there are seventeen steps, because I have both seen and observed.” (Holmes)

Step Two: Deduction

What inferences can we draw from our observations and facts?

"All day I turned these facts over in my mind, endeavouring to hit upon some theory which could reconcile them all. And to find that line of least resistance which my poor friend had declared to be the starting-point of every investigation.” — Dr. Watson, The Final Problem

Reason backwards: Work back from observations and effects to their root causes.

“The essential factor in this method consists in working back from observations of conditions to the causes which brought them about. It is often a question of deciding the doings of yesterday by the records found today.” — Thomas McCrae, The Method of Zadig

“The ideal reasoner… would, when he had once been shown a single fact in all its bearings, deduce from it not only all the chain of events which led up to it but also all the results which would follow from it.” — Sherlock Holmes, The Five Orange Pips

“In solving a problem of this sort, the grand thing is to be able to reason backward. That is a very useful accomplishment, and a very easy one, but people do not practice it much. In the everyday affairs of life it is more useful to reason forward, and so the other comes to be neglected.” — Sherlock Holmes, A Study in Scarlet

“There never was a sounder logical maxim of scientific procedure than Ockham’s razor… before you try a complicated hypothesis, you should make quite sure that no simplification of it will explain the facts equally well.” — Charles Sanders Peirce

“The inferences to be drawn from the observations—is a very different matter. Here the possibilities of error are much greater and what seems a simple diagnosis may involve complex inferences. A frequent mistake is to fail to recognize that there is any question of inference and to think that physical signs give a diagnosis directly.” — Thomas McCrae, The Methods of Zadig

“All parts of a living body are interrelated—they can act only in so far as they act all together. Trying to separate one from the whole means transferring it to the realm of dead substances. It means entirely changing its essence.” — Georges Cuvier

“When you hear hoof beats behind you, don’t expect to see a zebra.” — Proverb

“Common diseases cause uncommon symptoms more often than uncommon diseases cause common symptoms.” — Medical maxim

“Some of us are too much attracted by the thought of rare things and forget the law of averages in diagnosis.” — Thomas McCrae, The Method of Zadig

“In teaching the treatment of disease and accident, all careful teachers have first to show the student how to recognize accurately the case. The recognition depends in great measure on the accurate and rapid appreciation of small points in which the diseased differs from the health state. In fact, the student must be taught first to observe carefully.” — Dr. Joseph Bell, Dr. Joe Bell

“We ought not to be ignorant that the same remedies are not good for all.” — Celsus

When an event differs from what Sherlock Holmes expects, it draws his attention. What is out of the order or atypical?

Small pieces of information may in themselves look to be of no importance, but may clarify things when taken together with all of the facts and details.

“Let us take it link by link.” — Sherlock Holmes, Wisteria Lodge

“Experience has shown that a vast, perhaps larger, portion of the truth arises from the seemingly irrelevant.” — C. Auguste Dupin, The Mystery of Marie Roget

“Experience has taught me, and must have taught you, that the most trivial, commonplace and seemingly irrelevant facts have a way of suddenly assuming a crucial importance by connecting, explaining, or filling in the detail of later discoveries.” — Dr. Thorndyke, The Penrose Mystery

Strip away things that don’t count and focus on what matters: the core of the problem.

When in doubt, start by eliminating possibilities. What can we exclude?

“Another point is to endeavour to cultivate the habit of orderly thinking exactly as of orderly examination. As a rule it is possible in a problem of diagnosis to state all the possibilities and by exclusion narrow them down to one, possibly to two or more.” — Thomas McCrae, The Method of Zadig

“We must look for consistency. When there is a want of it we must suspect deception.” — Sherlock Holmes

“By the method of exclusion, I had arrived at this result for no other hypothesis would meet the facts.” — Sherlock Holmes, A Study in Scarlet

“I could think of no other adequate solutions. These, then, had to be sifted and balanced against each other.” — Sherlock Holmes, The Blanched Soldier

“Let us get a firm grip of the very little which we do know, so that when fresh facts arise we may be ready to fit them into their places.” — Sherlock Holmes, The Devil’s Foot

“There is only one possible way… We must fall back upon the old axiom when all other contingencies fail, whatever remains, however improbable, must be the truth. Here all other contingencies have failed.” — Sherlock Holmes, The Bruce-Partington Plans

Thought experiment: Assume a crime has taken place and you are faced with the problem of how the criminal escaped from a locked room. Sometimes it’s best to work forwards rather than backwards. The question is not how the criminal escape but how they got into the room in the first place. Often, the answer to one problem solves the other.

Step Three: Test Your Theory

If your theory disagrees with the facts, your theory is wrong. Never the facts.

"These deductions, gentlemen, must however be confirmed by absolute concrete evidence. Never neglect to ratify your deductions." — Dr. Joseph Bell, Dr. Joe Bell

“To choose a road, to stop habitually, and to ask whether you have not gone astray—that is the true method.” — Louis Pasteur

“It has been a case for intellectual deduction, but when this original intellectual deduction is confirmed point by point by quite a number of independent incidents, then the subjective becomes objective and we can say confidently that we have reached our goal. I had, in fact, reached it before we left Baker Street, and the rest has merely been observation and confirmation.” — Sherlock Holmes, The Sussex Vampire

“I have forged and tested every link of my chain, Professor Coram, and I am sure that it is sound.” — Sherlock Holmes, The Golden Prince-Nez

“Every link is now in its place and the chain is complete.” — Sherlock Holmes, Thor Bridge

“One should always look for a possible alternative and provide against it. It is the first rule of criminal investigation.” — Sherlock Holmes, Black Peter

“Have you any alternative theory which will meet the facts?” — Sherlock Holmes, The Sign of the Four

“Because we have in this case one singular incident coming close to the heels of another singular incident. The police are making the mistake of concentrating their attention upon the second, because it happens to be the one which is actually criminal. But it is evident to me that the logical way to approach the case is to begin by trying to throw some light upon the first incident—the curious will, so suddenly made, and to so unexpected an heir. It may do something to simplify what followed.” — Sherlock Holmes, The Empty House

When testing your theory or theories, remember that patience always helps. Take time to think things over and give yourself the space for connections between all the facts to arise.

“With your permission, gentlemen, we will now return to our cottage. For I am not aware that any new factor is likely to come to our notice here. I will turn the facts over in my mind.” — Sherlock Holmes, The Devil’s Foot

“I knew that seclusion and solitude were very necessary for my friend in those hours of intense mental concentration during which he weighed every particle of evidence, constructed alternative theories, balance one against the other, and made up his mind as to which points were essential and which were immaterial.” — Dr. Watson, The Hound of Baskerville

When you’re not getting anywhere, accept doing nothing for a bit and wait until more evidence is available.

“Well, I think we had best let matters develop a little further until we have clearer data.” — Sherlock Holmes, The Three Gables

Remember that distance lends perspective: Sometimes you just need to remove yourself from the problem in order to gain a fresh perspective on the problem.

“One of the most remarkable characteristics of Sherlock Holmes was his power of throwing his thoughts on to light things whenever he had convinced himself that he could no longer work to advantage.” — Dr. Watson, The Bruce-Partington Plans

“I gave my mind a thorough rest by plunging into a chemical analysis. One of our greatest statesmen has said that a change of work is the best rest. So it is. When I had succeeded in dissolving the hydrocarbon which I was at work at, I came back to our problem of the Sholtos, and thought the whole matter out again.” — Sherlock Holmes, The Sign of the Four

“Let us walk along the cliffs together and search for flint arrows. We are more likely to find them than clues to this problem. To let the brain work without sufficient material is like racing an engine. It racks itself to pieces. The sea air, sunshine, and patience Watson—all else will come.” — Sherlock Holmes, The Devil’s Foot

Some other tools.

A few other simple approaches and models to follow as you work to solve your own problems.

When you feel stuck, talk it over with someone else.

“There’s plenty of thread, no doubt, but I can’t get the end of it into my hand. Now, I’ll state the case clearly and concisely to you, Watson, and maybe you can see a spark where all is dark to me.” — Sherlock Holmes, The Man with the Twisted Lips

If you working on a problem with someone else, combine your experiences.

“There were two of us in the hunt, and when two men set out to find a golf ball in the rough, they expect to come across it where the straight line marked in their mind's eye crosses—from their original positions. In the same way, when two men set out to investigate a crime mystery, it is where their researches intersect that we have a result." — Dr. Joseph Bell, Dr. Joe Bell

Don’t make the world fit your tools. Use the right tool for the job.

“To my mind accurate habits of working and thinking are a great safeguard against the supposed short cuts to diagnosis.” — Thomas McCrae, The Method of Zadig

A rule is only a rule if it is always true.

“I never make exceptions. An exception disproves the rule.” — Sherlock Holmes, The Sign of the Four

Always be self aware and avoid overconfidence.

“My case is, as I have told you, almost complete. But we must not err on the side of overconfidence. Simple as the case seems now, there may be something deeper underlying it.” — Sherlock Holmes, The Sign of the Four

Update your beliefs whenever you get new information.

“I have devised seven separate explanations, each of which would cover the facts as far as we know them. But which of these is correct can only be determined by the fresh information which we shall no doubt find waiting for us.” — Sherlock Holmes, The Copper Beeches

Debate yourself: Have you tried to find evidence against what you believe? Why might you be wrong? What have you overlooked? What new information or evidence is needed to make you change your mind?

“When we meet a fact which contradicts a prevailing theory, we must accept the fact and abandon the theory. Even when the theory is supported by great names and generally accepted.” — Claude Bernard

“I have steadily endeavoured to keep my mind free so as to give up any hypothesis, however much below, as soon as facts are shown to be opposed to it.” — Charles Darwin

Confront your mistakes and learn from them. Do the work required to take away general principles that you can apply to similar problems in the future.

“There must be an honest reckoning of our mistakes. No part of the training is more essential. We all know the man who has made an incorrect diagnosis, but who, before the operation or post mortem is over, has nearly convinced himself that he did make the correct diagnosis and before night is quite sure of it. For him no good has come from the lesson. To learn we must face the mistakes and try to find out why we made them. Then comes our gain.” — Thomas McCrae, The Method of Zading

“We should all have the desire to reduce our errors to the minimum and to eliminate entirely those due to careless observations and slovenly habits of thinking.” — Thomas McCrae, The Method of Zading

Have a good sense for your limits.

“The best physician is the most conscious of the limitations of his art.” — Benjamin Jowett

“The best part of our knowledge is that which teaches us where knowledge leaves off and ignorance begins.” — Oliver Wendell Holmes

Now you know Sherlock Holmes methods. Apply them!

For more, I highly encourage you to order A Few Lessons From Sherlock Holmes and read the entire book yourself.

Recommended Reading

If you enjoyed A Few Lessons From Sherlock Holmes, you might also like:

• The Essays of Warren Buffett: Warren's Ideas from 50+ Years Grouped by Topic
• The Science of Hitting: From the Last Baseball Player to Break the Magic .400 Barrier
• A Few Lessons From Sherlock Holmes: Learn to Think Like the Famous Detective
• Turning the Flywheel: Why Some Companies Build Momentum and Others Don't
• The Tao of Charlie Munger: Wisdom on Life, Business, and the Pursuit of Wealth

Related Collections

You can find other books like A Few Lessons From Sherlock Holmes in these collections:

• Ten Books with the Most Page-for-Page Wisdom
• Best Business Books
• Best Investing Books
• History's Greatest Speeches and Talks
• History's Greatest Letters and Memos

‍

‍