The Many Minds of Sherlock Holmes

Can we really learn to think like Sherlock?



At the Museum of London earlier this year was an exhibit titled “The Man Who Never Lived and Will Never Die.” As a long-time Sherlock Holmes enthusiast as well as a practicing philosopher, I know this to be true. Since his first appearance in 1887, the great detective has been memorialized by over a hundred actors in dozens of plays, films, radio, and television adaptations, as well as in countless works of fiction. In the last few years alone, Holmes’s immortality has been demonstrated in original television series like Sherlock and Elementary and in highly imaginative movies like the blockbuster action series Sherlock Holmes, starring Robert Downey, Jr., and the poignant elegiac Mr. Holmes, starring Ian McKellen.

What lies behind our enduring fascination with this character and this surge of current interest in particular?

Holmes offers Watson a number of rules for what directs his work as a detective. I have extracted these rules from his stories and novels as follows:

  • “In solving a problem of this sort, the grand thing is to be able to reason backwards.” (A Study in Scarlet)
  • “When you have eliminated the impossible, whatever remains, however improbable, must be the truth.” (The Sign of the Four)
  • “It is a capital mistake to theorize before you have data. Insensibly one begins to twist facts to suit theories instead of theories to suit facts.” (A Scandal in Bohemia)
  • “We balance probabilities and choose the most likely. It is the scientific use of the imagination.” (The Hound of the Baskervilles)
  • “Crime is common. Logic is rare. Therefore it is upon the logic rather than upon the crime that you should dwell.” (The Adventure of the Copper Beeches)

These are the stated principles behind the Holmesian method, but they are hardly the full story. Recently, several authors have gone beyond merely uncovering the principles supposedly at work in the mind of Holmes and attempted to convince us that almost anyone can learn to think like Sherlock himself. By more consistently adopting these principles and by using the techniques of “mindfulness,” partnered with the constantly expanding knowledge we are getting from neuroscience in “mapping” the brain, the claimants argue, we can soon be on the glory road to thinking more like Conan Doyle’s genius than we ever thought possible.

Many of the recommendations in these books and articles contain some very good, if very old, advice. The trouble with these assurances that we can achieve Holmesian brilliance in this way, however, is simply this: You cannot get to that luminous place of understanding embodied by Sherlock Holmes by simply increasing your powers of observation, amplifying your focus on the essential (versus the incidental), attending only to “facts,” and avoiding the urge to jump to conclusions. Holmes tells Watson that the brain is “like a little empty attic” that “has to be stocked with the right kind of furniture,” and we are told that this is one of the keys to mindfulness. But what can he mean by the brain, and what kind of furniture is he talking about?

To at least one adherent of this “mindfulness” approach, the comparison is right on the mark:

For Sherlock Holmes, a person’s brain attic really is an incredibly concrete, physical space. Maybe it has a chimney. Maybe it doesn’t. But whatever it looks like, it is a space in your head, specifically fashioned for storing the most disparate of objects. That comparison, as it turns out, is remarkably accurate. Subsequent research on memory formation, retention, and retrieval has proven itself to be highly amenable to the attic analogy.1

Yet, Holmes also and inconsistently tells his colleague that success in finding solutions to a crime often depends on approaching the case with “an absolutely blank mind.” So much for attics well-stocked, chimney or not.

Anchoring these claims of “mindfulness” to the exclusive brain-talk of neuroscience misses a key point about how our minds — and Sherlock’s — actually work. The mind is not merely the brain, and even if it were, a brain is not anything like an attic and is not stocked with anything like furniture. It is not “stocked” at all, in fact, but is linked with our beliefs and other habits of thought: with how-to knowledge as well as factual knowledge; with the moral and aesthetic values we hold and how we rank them; with love, hate, and other emotions. Our intuitions, likes and dislikes, memories, rules of reasoning, ability to use language, power to appreciate art and music, sense of what is relevant and what is not in trying to manage the challenges life tees up for us — these are not “things” in the brain and they are not “located” anywhere. To call these and related mental capabilities “things” is a classic example of what philosophers sometimes describe as a Category Mistake, akin to arguing that since we can speak about “things” like Euclidian triangles and can also speak of “things” like trees, they must both be objects that can be found in some place.

This brain-as-mind philosophical position actually undermines what the mindfulness votaries are recommending we train ourselves to do. For if all our mental and emotional lives are merely states of the brain — including our beliefs about the world we live in — then, like characters in The Matrix or the residents of Plato’s Cave, there is no real world other than what we construct out of our own perceptions. As philosopher Alva Noë explains:

The concern of science, humanities and art is, or ought to be, the active life of the whole, embodied, environmentally and socially situated animal. The brain is necessary for human life and consciousness. But it can’t be the whole story. Our lives do not unfold in our brains. Instead of thinking of the Creator Brain that builds up the virtual world in which we find ourselves in our heads, think of the brain’s job as enabling us to achieve access to the places where we find ourselves and the stuff we share those places with.2

When you are told that to truly imitate Holmes you must “Deduce — Only from What You’ve Observed and Nothing More,”3 you are being told what is logically impossible. Teaching anyone to stick to the observed facts and to reason only from them is a futile enterprise unless one brings the skills, beliefs, and knowledge one has in mind to the operation: abilities gained by concrete experience and demonstrably useful in the moment. Just as an absolutely blank mind would be totally valueless in determining what was a relevant fact to pursue and what was not — pace Holmes in one of his rules — reasoning only from what one observes would be incomprehensible. To call something a fact is to already label it as something of interest and observed from a particular point of view, which means that a prior relevant knowledge framework is already at work. (This might be why the “attic” mysteriously and suspiciously changes into “the Dynamic Attic” later on in Konnikova’s book: the “furniture” appears to have become alive and is magically kicking.)

Indeed, the techniques that the mindfulness adherents recommend seem conceptually independent of whether or not they follow the canons of sound logic, generate the true answer, crack the case, and identify the right culprit in the crime. Holmes might be admired because of his amazing powers of concentration and his penetrating focus on the details of crime scenes. He would not be heralded, however, if he consistently failed to get the correct outcome. This can happen only if his reasoning holds up, if the hypotheses he proposes to solve a case are logically coherent and have depth and predictive power, if the processes by which he confirms their truth pass muster and are not one-sided. This has little to do with how observant he is; it has all to do with following the mind-independent canonical rules of sound inductive, abductive, and other forms of non-deductive logic.

Yet if I stop here in assuming that this is how Holmes thinks and how we should think effectively, I would be doing a disservice. For to think like Sherlock Holmes is not just to bring the powers of mindfulness to bear, it is to bring many minds to bear, working from different points of view while still focusing in laser-like collaboration on the same problem and at the same time.

The great late 19th century French criminologist and pioneer of forensic science, Alexandre Lacassagne, enjoyed reading the Holmes stories but, nevertheless, observed that no one could really solve crimes by himself the way Holmes did. It took the careful teamwork of other experts who brought their vast and varied skills, intuitions, imagination, and deep experience into the investigation to get the science right and to make sure nothing was left to guesswork or chance.4 Lacassagne should have realized, however, that Sherlock Holmes had all he needed of specialists and their expertise already at hand in his own inquiring mind, a mind already populated with a superb lineup of top-drawer professionals.

We know from the early pages of A Study in Scarlet that Holmes was well-schooled in the science of chemistry; indeed Watson, while telling us that Holmes knew nothing of literature, philosophy, or astronomy and very little of politics, nevertheless calls his knowledge of chemistry “profound.” (The Royal Society of Chemistry actually gave the detective an honorary, though “posthumous” fellowship.) Watson also relates that Holmes had an “immense” knowledge of the literature of crime and knew “every horror perpetrated in the last century.” His knowledge of anatomy was also discernible throughout several of the stories, as are references he makes to monographs he had written on areas like the typewriter’s use in criminal detection, identifying the different types of tobacco ashes, the structures of the human ear, the classification of footprints, and a book he had planned to finish on the use of dogs in solving crimes. Holmes was also demonstrably knowledgeable about botany, British law, fingerprinting, handwriting analysis, various types of poisons, and dust. He could expertly unravel ciphers and codes, distinguish the different kinds of soils, and identify types of guns, bullets, and gunpowder. As an actor and master of disguise himself, he was able to sense when suspects and witnesses were lying. In short, Sherlock Holmes just by himself had the ability to profoundly and capably collaborate whenever he needed to.

To think like Sherlock Holmes, then, one would surely have to have a mind — or minds — very much like his and an ability to connect to the world of others from multiple perspectives — others with the power to see into any situation from a divergent but complementary array of applicable perspectives and to project hypotheses that could meaningfully explain the pertinent data and the significant possibilities of almost any given situation. Holmes’s ability to do this enables him to both refrain from premature commitment to a solution as well as move him toward a productive resolution as the many minds operating on a problem converge.

Genuine collaboration is what spurs the expanding horizons of imagination, creates serious dialogue, and provokes the exchange of ideas and perspectives and the appreciation of other points of view. Yet these kinds of teamwork and cooperation also make possible by their very nature the needed restraints from drawing impulsive conclusions precisely because complexity and depth are truly valued throughout the process.

There is, then, a serious and multi-leveled conversation going on among the experts in the many minds of Sherlock Holmes as he approaches a problem, calls for and seeks out more data, and tries out and assigns degrees of probability to the several hypotheses he is entertaining. The reader and the other characters in the stories — often including Dr. Watson — cannot hear the discussion, of course, and even if they could it might be too difficult for non-experts to follow clearly.

Books of rules that advise us how to think more clearly and more carefully have been around forever. Many of the more recent ones can be useful, as we have noted, despite their dubious philosophical infrastructure. There is no real hope that they can teach us to be — even to imitate — a thinker like the sleuth of Baker Street unless we, too, have available the wide range of experience and skill at work in his many minds.

We know, indeed, that Sherlock Holmes never lived. At the same time, we ought to understand the reason why he will never die. Admiring the engrossing conversation that goes on in the many minds of the world’s most famous consulting detective, we seem never to stop trying to be part of it ourselves. •


  1. Shane Parrish (@farnamstreet), “How to Think Like Sherlock Holmes” quoting Maria Konnikova in Mastermind: How to Think Like Sherlock Holmes, New York: Penguin, p. 26. ^
  2. Alva Noë, “How Art Reveals the Limits of Neuroscience, “The Chronicle Review, September 11, 2015, p. 10.
  3. Konnikova, p. 217. ^
  4. A comprehensive profile of Lacassagne’s groundbreaking methods can be found in Douglas Starr’s The Killer of Little Shepherds: A True Crime Story and the Birth of Forensic Science, New York, Vintage Books, 2010.^
Fred J. Abbate is a professor in the Pennoni Honors College at Drexel University. He has written several books and numerous articles on philosophy, as well as a mystery novel.

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