top of page

Unlock Your Inner Sherlock: Case One "A Study In Scarlet"

© 2018 TheScienceOfDeduction.Org All rights reserved

This is a rough draft of a novel idea I have for exploring how Sherlock Holmes thinks. Each chapter will be a "case study" of Sherlock Holmes and his methods. Feel free to offer suggestions and comments by leaving me a line at


The phrase, “It’s elementary my dear Watson”, appears nowhere in the original stories of Sherlock Holmes penned by Sir Arthur Conan Doyle. Holmes’ process is anything but elementary. Maybe that’s why Conan Doyle didn’t have him say that, even though I can totally imagine Holmes saying something like that. In the stories, Sherlock displays powerful lines of logic and reasoning capabilities.

For example, in our first meeting of Sherlock Holmes we are introduced to Sherlock Holmes. “You have been in Afghanistan, I perceive.”

“How on earth did you know that?” I asked in astonishment. Watson’s surprise is genuine and I don’t blame him. Holmes had never met Watson before this moment and Watson’s friend, the one that introduced the two, had not informed Holmes of Watson’s existence. Yet Holmes asks a very particular question about Watson’s recent past with clarity and precision. “You have been in Afghanistan.” That’s such a cool statement to make.

How do you observe someone for the first time and recognize where they have been? How do you draw big conclusions from small details? How do you begin to think like Sherlock Holmes? The answer is elementary, but it will take a while to explain some of the details. Let’s get started with the basics and work our way up to the basics. You read correctly. Thinking like Sherlock Holmes is in itself basic, but there are many layers to the steps. Additionally, there will be plenty of effort required to enact the changes that are necessary to start the journey. But don’t worry. This book will help you navigate those waters.

In the book a number of the ideas presented will be re-emphasizing of ideas that are core to deductive and inductive reasoning. Also a constant exploration of lateral thinking and analysis of situations will be written about extensively. I want to stress that a lot of the thought processes Sherlock performs are repetitive and he has some common principles that govern his thoughts.

Let’s start with the first example of Holmes and Watson’s first meeting to demonstrate how we can replicate the great detectives process.

“You Have Been In Afghanistan”

To begin this study, I would like to discuss how we see the world around us. Your eyes are a powerful tool for taking in information. One of the most powerful skills of Sherlock Holmes involves his ability to see the world differently than the rest of us. Though we see, hear, smell, touch, and taste a seemingly endless array of things, our brain does not force us to register everything. This is to our benefit.

Imagine for a moment if your Prefrontal Cortex (PFC), the CEO of the brain, were to figuratively say, “I know you are driving down the highway at 60 miles per hour, but I noticed there was a banana peel on the highway. Turn your head please and look at it.” That probably wouldn’t be the best idea. In the grand scheme of things, that banana peel probably wasn’t worth your time. Your PFC does a great job at prioritising what is relevant and what isn’t, what is useful for the task at hand and what is a waste of your brains resources. Just as a literal CEO has to manage the resources of a company to execute a plan, your PFC has to manage the brains resources to help you navigate life.

When driving a car, the best use of your mental resources is to focus on the world around you and how you manage your steering wheel, gas pedal, brakes, and instrument panels. When playing a game of tennis, your best use of mental resources are to focus on the ball, your position, and the position of your opponent. But how do we get good at any of these tasks? We train our brains to perform these complex tasks by repetition/practice, analysis, and performance. In time, a task like playing a musical instrument can become second nature. Let’s explore the meeting of Sherlock Holmes and Watson in The Study In Scarlet.

When Sherlock sees Watson for the first time, I speculate that he didn’t spend more than a glance looking at Watson. Let’s read that passage.

At the sound of our steps, he glanced round and sprang to his feet with a cry of pleasure. “I’ve found it! I’ve found it,” he shouted to my companion, running towards us with a test-tube in his hand. “I have found a re-agent which is precipitated by hemoglobin, and by nothing else.” Had he discovered a gold mine, gred not have shone upon his features.

“Dr. Watson, Mr. Sherlock Holmes,” said Stamford, introducing us.

“How are you?” he said cordially, gripping my hand with a strength for which I should hardly have given him credit. “You have been in Afghanistan, I perceive.”

What did the text say? “He glanced round”. He then came towards Watson and his companion. Afterwards, he shook hands with Watson and made his claim about Watson recently being in Afghanistan. So the time that Holmes had spent actively observing Watson was likely no more than a couple of seconds, if that.

In fact, later in the story Holmes says, “Nothing of the sort. I knew you came from Afghanistan. From long habit the train of thoughts ran so swiftly through my mind, that I arrived at the conclusion without being conscious of intermediate steps. There were such steps, however. The train of reasoning ran, ‘Here is a gentleman of a medical type, but with the air of a military man. Clearly an army doctor, then. He has just come from the tropics, for his face is dark, and that is not the natural tint of his skin, for his wrists are fair. He has undergone hardship and sickness, as his haggard face says clearly. His left arm has been injured. He holds it in a stiff and unnatural manner. Where in the tropics could an English army doctor have seen much hardship and got his arm wounded? Clearly in Afghanistan.’ The whole train of thought did not occupy a second. I then remarked that you came from Afghanistan, and you were astonished.”

Why does it matter that Holmes was able to glean that much information so quickly from a glance?

It matters because one of the first effects it has on us and Watson is the feeling of suspicion as well as disbelief. How did he come to that conclusion without ever having met Watson? It’s like an unsolvable puzzle has just been solved right in front of our eyes. But that’s the thing I want to highlight. The speed at which he reaches a conclusion is what makes his process amazing, not the actual process itself.

To illustrate, imagine seeing a concert pianist perform. They dazzle the audience with a tight rope act of brilliant piano passages. To reach the level of concert level, a pianist must practice, analyze and perform music over and over and over again. This process in itself isn’t complicated, but it takes years to prepare and cultivate the talent that brings a person to concert level. Likewise, Sherlocks process isn’t really complicated but it would have taken years of practice to cultivate. With that in mind, let’s explore the tools Holmes uses to reach his conclusions.

“I have a lot of special knowledge which I apply to the problem, and which facilitates matters wonderfully,” and “I have a kind of intuition...observation to me is second nature.” Holmes declares he has an array of tools that help him to reach his conclusions. Let’s list them so that we are clear of what they are:

  • Observation

  • Intuition

  • Special Knowledge

Let’s take these one at a time to see what we can learn before going into Holmes process of deductive and inductive logic.


I offer that Sherlock Holmes observation ability is the same as yours. Yes, you read that correctly. You have the same ability to observe as Sherlock Holmes. But wait, Holmes sees so much and I have no idea how he gets to his conclusions, how is it that I can see what he sees? As long as you have eyesight you can observe the same things that the great detective does. So what’s the difference?

The key difference between Holmes’ observation ability and yours is he is actively looking for something, that and he has practiced, analyzed and performed this ability for years. He has primed himself to search for specific things.

I remember teaching ECG to a brand new ECG technician. ECG scans are those little blips on a screen that show the electrical activity of the heart. When a patient gets hooked up to a monitor, they wear these little “electrical cameras” called leads. If a patient moves or the leads (cameras) get messed up, the image tracing can become unclear. When the image is unclear in any way, knowledge of how the heart functions is vital to an ECG technician. The technician needs to be able to glean truth from blur.

One of the first things a technician will do to reach an interpretation of the rhythm they see is ask if the patient’s heart rate is regular or irregular? This question is important because the heart’s primary pacemaker fires at a regular rate. It fires predictably. Asking this question can easily help the technician discern what’s actually happening in the heart, despite the noise they have to look through.

This question isn’t asked just once or twice, but countless times. It requires discipline and constant ingrained prompting internally to ask the question every time an ECG is seen. If this question is ignored, the interpretation of the information will likely be wrong, despite the experience of the technician. I gather that this line of question or type of question isn’t unique to ECG analysis. Technician work of any kind requires a disciplined line of thought to ensure that the information being looked at is filtered properly. A series of diagnostic questions are essential when trying to reach accurate conclusions whether you are a physician or a mechanic.

A seasoned professional of any kind isn’t looking at everything that comes their way, they are looking for primary things that help them reach accurate conclusions when diagnosing or coming up with a strategy to employ. They do this quickly because they have primed themselves to follow the exact same process of looking at the primary things first then for the obscurities. Knowing this helps us because when we see Sherlock Holmes in action, we understand that he isn’t looking at everything. Yes he sees everything, but he isn’t looking at everything. What are some of the things that he is looking for or observing?

In the stories, Holmes is able to identify the occupation of potential clients on a glance. Let’s explore what he would be looking for.

What signs would you look for to identify a person's job? Perhaps a look at physical build, mannerisms, or body language can yield an answer. Maybe a smell or an identification card could help. Whatever the case, I gather that in Sherlocks time, occupation was probably an easier thing to identify. Let’s make a list of some of the occupations that Sherlock would see in his city.

In the list below, the top ten occupations in London are given for the year 1851. Take note that the top two occupations are more than double the amount of the third occupation. This would mean that Holmes would likely encounter more than double the amount of agricultural labourers, farm servants, shepherds, and domestic servants than any other occupation. This wouldn’t guarantee that he would see these people with every case, but searching for elements of their occupation would certainly be at the forefront of his mind. Signs of these first jobs would be what he would look for before all others.

Table 1.1 London 1851 Census

1.) Agricultural labourer, farm servant, shepherd


2.) Domestic servant


3.) Cotton, calico, manufacture, printing and dyeing


4.) Labourer


5.) Farmer, grazier


6.) Boot and shoe maker


7.) Milliner, dressmaker


8.) Coal miner


9.) Carpenter, joiner


10.) Army and navy


I got this list from the website On the site, they list a census date for each of the occupations in Victorian London. The list is pretty extensive. Regardless of if this list is 100% accurate or not, it illustrates the point that when searching for something like an occupation, you can play the numbers in your favor. Sherlock wouldn’t look for signs of the least likely job occupation when encountering someone for the first time. He would look for the most likely candidates first.

Let’s take a look at number nine on our list, coal miners. Coal miners were subject to deplorable working conditions in the 1800’s. They might work in damp and dark environments for hours. Their work also was subject to danger. Being in an enclosed space, oxygen levels could be low and if there was a cave in, miners could die. One of the main things that surrounded coal miners was various types of dirt, clay, and rock.

So what would Sherlock Holmes look for if he tried to identify someone as a coal miner? More importantly, what would you look for? An important takeaway from this study is realizing that you can, and already do, think like Sherlock Holmes. But it’s important to realize that Holmes has trained and primed himself to look for specific things over many years. But let’s examine that question, “what would Holmes look for if he was trying to identify a coal miner”?

The first thing he would look for is coal stains. Perhaps the person he observes has a smudge stain on their face or clothing if they came from their job. Holmes would also make a study of the majority of coal miners and typical body structure and mannerisms of coal miners. Perhaps they tend to stretch their backs constantly due to being confined in tight spaces for long hours. Maybe they squint their eyes constantly due to the low lighting conditions they work in or have a slight aversion to bright lights. Maybe they exhibit certain respiratory issues. Maybe they have a distinct smell to them. Whatever the study yielded, Sherlock would then add the tell signs of that occupation to his observation list - the list of things he would look for when encountering a coal miner.

Exercise: Take a look at the above list and select two occupations. Of those two occupations, write down at least three things that you would look for when identifying a person belonging to that occupation. Ask yourself, where would you see the evidence, what posture or body language would the person have, what kind of smell might they omit, and what visible signs would you see of their occupation? Once you compile your list, research the the living conditions and working conditions typical of a person with that occupation in Victorian London. After you have completed the exercise try this with a couple of modern day occupations. Keep refining the tell signs of a specific job or major job group.

Let’s recap. Sherlock isn’t really doing anything incredible when he observes the world around him. He is actively looking for specific things. Because Holmes has practiced the task countless times, his ability to observe quickly combined with knowing what he is looking for helps him reach conclusions much faster than the typical observer. With practice and time, you can reach an efficient level of skill. But there is a little bit more to Holmes talent that I wish to explore. Let’s look at his intuition and how it plays into his ability to observe.


If Holmes was a real person, his skill at observation may have been innate. As he says in the Study of Scarlet, “observation to me is second nature.”

What does that mean exactly? “Second nature” implies natural talent. I don’t know any person that I have met that is naturally good at observation, at least not at the level that Sherlock takes it. His observation skills run at the level of almost an eidetic memory. To anyone unfamiliar, eidetic memory is the ability to recall information with high amounts of detail. For example a person with an eidetic may be able to recall how many ants were on the ground if they looked down and saw them scurrying about.

Since the stories don’t specify which type of memory Holmes has, I can only speculate that his ability to observe is naturally very high. Whether he uses mnemonic devices or has an eidetic or photographic memory, I can’t say. But his ability to observe is natural and innate. But even the best of our talents must be drawn out and explored. Mozart may have been born a genius, but it still took hours and hours of study and practice to hone his craft. He didn’t just rely on his natural ability. He had to improve it over the years.

Home your craft

So your intuition and natural abilities may not be on Sherlocks level, but that shouldn’t stop you from trying. Mozart performed most of his life as either a violinist, pianist, singer or conductor. He was constantly working. When he was a child Mozart was brought on tour through Europe, by his father, showcasing his talents. It’s no surprise that he advanced his abilities and continued to thrive into adulthood. His abilities as a concert pianist were incredible, but that’s not what we really remember him for. We remember him for his compositional ability.

But if you take a look at the piano music of Mozart and compare it with the piano music of Sergei Rachmaninoff, a Russian composer/virtuoso pianist born in 1873, you will notice some differences in their music. The first thing I notice is the amount of notes that have to be managed, as well as the harmonies that you encounter. Technically, a pianist has to contend with a lot more when playing Rachmaninoff than Mozart. Let’s look at two scores in comparison.

Figure 1. Passage from Rachmaninoff's 3rd Piano Concerto

Figure 2. Opening notes to Second Movement of Mozart's Piano Concerto No. 23

After examining the scores, consider this point. Pianists have surpassed the playing ability of a born genius. Yes, Rachmaninoff was a virtuoso pianist, but he too had to work to cultivate his talent. This is the take away, intuition is akin to natural talent. People have various talents and abilities that they are born with. Just as Sherlock Holmes may have been born with natural memory or observation skills, he still needed to hone his craft. No person can achieve high levels of ability without effort and work. If you want to learn to think like Sherlock Holmes, you will have to work hard to cultivate your talent.

Exercise: Take five to ten minutes and write down your natural talents and abilities. Focus on the talents and skills that most contribute to your current goals. Sherlock wouldn’t waste his time cultivating his skills on something that won’t allow him to be the best version of himself. Select 3 things that you can work on every week. This could be being a more engaging family member or maybe a more well spoken HR representative. Whatever skills best serve you to achieve your goals are the ones you want to focus on.

Let’s re-emphasize the point that intuition is related to talent. It’s something that is natural, but it must be cultivated. Work and time must be applied towards your specific skills and goals in order to reach a level that is comparable to that of Sherlock Holmes. Your cultivated skill doesn’t need to be about observation or deductive reasoning. Choose the skills that best suite you and your needs. Select three specific skills to work on throughout a week. Stick with those skills long enough to get better at them. Don’t waste your time cultivating skills that don’t contribute towards your main goals.

Special Knowledge

In a Study In Scarlet, Watson becomes fascinated by his new companion. Watson is amazed that he Sherlock doesn’t know or conveys that he does not know that the planets move around the sun. Let’s read that passage.

“You appear to be astonished,” he said, smiling at my expression of surprise. “Now that I do know it I shall do my best to forget it.”

“To forget it!”

“You see,” he explained, “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 that 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 difficulty in laying his hands upon it. Now the skilful 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 that you knew before. It is of the highest importance, therefore, not to have useless facts elbowing out the useful ones.”

“But the Solar System!” I protested.

“What the deuce is it to me?” he interrupted impatiently; “you say that we go round the sun. If we went round the moon it would not make a pennyworth of difference to me or to my work.”

This reveals a philosophy of thought that Sherlock Holmes adopted about the world around him and the information he let into his own. He didn’t allow his precious mental resources to be depleted by storing away facts and information that didn’t matter to him and his consulting work.

The world we live in today is a complex filled with a seemingly endless supply of information and distractions. What are some things that distract you? For the longest time things like Facebook, Instagram, Youtube, random Google searches, and news would waste a lot of my time. I always wanted to be in the loop and to feed my mind with things that in hindsight, add little value to my day to day abilities. Now before I proceed, I am not saying in any way that those things don’t add value to people's lives. But there is a big difference between being entertained or informed about something specific and allowing those things to control your day to day thinking.

To illustrate this point, do you recall the outbreak of Ebola that occured in Africa in the years of 2014-2016? Chances are you do. It was a major news story. But a more important question is, “What is did you do to change the outcome of the lives of those with Ebola? Did you go to Africa and help contain the virus? Did you send letters to the families of those that were suffering because of it? Did you raise money to help in the aide work? If I didn't bring up Ebola, would it have been something you thought about today?

The intention of these questions is not to make you feel bad, or to get you to take action on major social issues. The point is to highlight that there are many major issues and problems that occur in the world. Even with issues that we should know about, many of us do little to nothing to actively fix them. The difference between what we know and what we do are very different things. Sherlock takes this to the extreme. He avoids all information that does not relate to his work. So what are the things that he focuses on? What special knowledge was worth his time?

Dr. Watson provides a list for us.

  1. Knowledg of Literature - Nil.

  2. Philosophy - Nil.

  3. Astronomy - Nil.

  4. Politics - Nil.

  5. Botany - Variable. Well up in belladonna, opium, and poisons generally. Knows nothing of practical gardening.

  6. Geology - Practical, but limited. Tells at a glance different soils from each other. After walks has shown me splashes upon his trousers, and told me by their colour and consistency in what part of London he had received them.

  7. Chemistry - Profound.

  8. Anatomy - Accurate, but unsystematic.

  9. Sensational Literature - Immense. He appears to know every detail of every horror perpetrated in the century.

  10. Plays the violin well.

  11. Is an expert singlestick player, boxer, and swordsman.

  12. Has a good practical knowledge of British law.

Even in Sherlocks time, he had to contend with a world that was vying for his attention. But he didn’t allow those things to encroach upon his mind and become the things that determined his thinking. I think if Sherlock was alive in the 21st century, he wouldn’t read or watch the news, unless it involved crime. He wouldn’t spend time on social media or care about the general ebb and flow of the world around him. He would only focus his attention on acquiring information that was relevant to his ability to improve as a consulting detective as the above list shows.

I want to spend a moment to highlight the piece of information that Sherlock knows the most about. He seems to have a knowledge that is extraordinary when it comes to criminal activity. He was a student of crime. I will touch on some of the other subjects Holmes knows about, but it's important that we key in on his knowledge of crime.

Crime, like any other thing, has a history. I take it that Sherlock was one of it’s historians and compilers. We find that Sherlock is actually rather bored with criminals in his days because they lack creativity when it comes to committing their crimes. He says, “There are no crimes and no criminals in these days,” he said, querulously. “What is the use of having brains in our profession. I know well that I have it in me to make my name famous. No man lives or has ever lived who has brought the same amount of study and of natural talent to the detection of crime which I have done. And what is the result? There is no crime to detect, or, at most, some bungling villainy with a motive so transparent that even a Scotland Yard official can see through it.”

I find it interesting that he is disinterested in general crime because it is so common place to him. He says that there “is no crime to detect.” He doesn’t mean there is an absence of crime, but an absence of interesting crime. Holmes has such a strong ability to see the common threads in everyday crimes, that they no longer interest him. He's researched the subject so much that common crime bores him. In effect, he has become a specialist.

But when he solves cases, I gather that he is not just drawing on his ability to use deductive and inductive reasoning. It is not just his ability to solve problems and work through his brain attic. Holmes is able to draw on his immense knowledge of crime to help him guide his thinking. He was an informed thinker.

Let’s draw some inferences about Sherlocks talent to solve problems from Doctors. You might have a little knowledge about how your body operates. You understand that if you have a cold, you need some rest and maybe some medicine and liquids to get better. On a hot day, if you are lightheaded, you might need to sit down and drink some water. But what if you have a life threatening medical problem? You probably will consult a physician.

Depending on the medical problem you encounter, you may need a specialist. Doctors may specialize in a specific type of medicine. These specialists have specific knowledge to solve problems that require unique expertise. To get this special knowledge, they study journals and case studies of their field of interest. They conduct studies about new cases they encounter. They attend seminars and lectures of other specialists. They know the history and for all purposes the most current knowledge about their field of study.

Sherlock Holmes would do the same types of things to get his knowledge and special skills. He would have had to work hard to compile news articles and encyclopedias that contained crime incidents. He may have questioned or interviewed investigators about specific crimes. He may well have spent time solving old crimes to add to his working knowledge of how specific crimes were committed. Perhaps he even created scenarios of crimes and how he would commit them.

However he got his knowledge of crime, Sherlock must have spent many years acquiring it and many hours continuing to keep it stored in his mind. It served as a reference for his other subsequent skills. What’s the takeaway?

If you want to think like Sherlock Holmes, you shouldn’t spend your time acquiring knowledge and skills that don’t serve your purpose. Avoid time wasters and other things that may leave your mind unfocused and wandering. Be a relentless student of your craft. This may take many months of cataloguing information and studying core and complex information related to your subject or field of study.

Wrap Up

There is so much more to discuss in this chapter but I wanted to wrap it up so that I can move onto some of the other aspects of Sherlock Holmes thinking. If we look at the Study In Scarlet, we find that Sherlocks abilities are amazing because of the speed at which he performs them. He uses his observation, intuition, and special knowledge to dazzle us with those deductions. If you want to think like Holmes, you will have to spend time focusing on the things that really matter/play the numbers (observation), you will have to cultivate your talent (intuition), and you will have to be relentless at archiving information that is relevant to your field of study and avoid time wasters.

309 views0 comments

Recent Posts

See All

Transitive Inferences A Short Post

Exercise Michael is taller than Jan Jan is shorter than Kelly Dwight is taller than Jan Stanley is shorter than Robert Robert is taller than Michael Can you arrange the people in order from tallest to

bottom of page