Mastermind: How to Think Like Sherlock Holmes

by Maria Konnikova

  As for the stick itself, here, too, the good doctor has not been as careful in his observations as he should have been. First off, he merely glances at it, whereas Holmes “examined it for a few minutes with his naked eyes. Then with an expression of interest he laid down his cigarette, and, carrying the cane to the window, he looked over it again with a convex lens.” Closer scrutiny, from multiple angles and multiple approaches. Not as fast as the Watson method, to be sure, but much more thorough. And while it may well be true that such care will not be rewarded with any new details, you can never know in advance, so if you are to truly observe, you can never afford to forego it. (Though, of course, our own window and convex lens may be metaphorical, they nevertheless imply a degree of closer scrutiny, of scrupulousness and sheer time spent in contemplation of the problem.)

  Watson notes the stick’s size and the worn-down bottom, true. But he fails to see that there are teeth marks plainly visible on its middle. Teeth marks on a stick? It’s hardly a leap of faith to take that observation as implying the existence of a dog who has carried the stick, and carried it often, behind his master (as Holmes, in fact, does). That, too, is part of the observation, part of the full story of Dr. Mortimer. What’s more, as Holmes points out to his friend, the size of the dog’s jaw is evident from the space between the marks, making it possible to envision just what type of dog it might have been. That, of course, would be jumping ahead to deduction—but it wouldn’t be possible at all without recognizing the necessary details and mentally noting their potential significance for your overall goal.

  3. Imagine—Remembering to Claim the Space You May Not Think You Need

  After observation comes that creative space, that time to reflect and explore the ins and outs of your attic called imagination. It’s that break of the mind, that three-pipe problem, that violin interlude or opera or concerto or trip to the art museum, that walk, that shower, that who knows what that forces you to take a step back from the immediacy of the situation before you once more move forward.

  We need to give Watson some credit here. He doesn’t exactly have time to take a break, as Holmes puts him on the spot, challenging him to apply the detective’s methods to inferring what he can about the implications of C.C.H. standing for Charing Cross Hospital instead of for Something Hunt. Watson can hardly be expected to break out the cigarettes or brandy.

  And yet Watson could do something a little less extreme but far more appropriate to a problem of far lesser magnitude than solving a full crime. After all, not everything is a three-pipe problem. It may be enough to take a more metaphorical step back. To distance yourself mentally, to pause and reflect and reconfigure and reintegrate in a much shorter time frame.

  But Watson does no such thing. He doesn’t even give himself time to think after Holmes prompts him to do so, saying that he can only draw “the obvious conclusions” but can’t see anything further.

  Contrast the approach that Watson and Holmes take. Watson goes right to it: from observation of the heft and shape of the stick to image of old-fashioned practitioner, from C.C.H. to Something Hunt, from worn-down iron ferrule to country practitioner, from Charing Cross to a move from town to country, and nothing more besides. Holmes, on the other hand, spends quite a bit more time in between his observations and his conclusions. Recall that first, he listens to Watson; next, he examines the stick; then, he once more speaks with Watson; and finally, when he begins to list his own conclusions, he does not do so all at once. Rather, he asks himself questions, questions that suggest a number of answers, before settling on a single possibility. He looks at different permutations—could Dr. Mortimer have been in a well-established London practice? A house surgeon? A house physician? A senior student?—and then considers which would be more likely in light of all of the other observations. He doesn’t deduce. Rather, he reflects and he plays around with options. He questions and he considers. Only after will he start to form his conclusions.

  4. Deduce—Only from What You’ve Observed, and Nothing More

  From a walking stick to a “successful, elderly medical man, well-esteemed,” a “country practitioner who does a lot of his visiting on foot” and who has “given some surgical assistance” to a local hunt (for which he has received said stick), if you’re Watson. And from that same stick to a former Charing Cross Hospital “house-surgeon or house-physician,” a “young fellow under thirty, amiable, unambitious, absent-minded, and the possessor of a favourite dog”—nay, a curly-haired spaniel—who received the stick on the occasion of the change from Charing Cross to the country, if you’re Holmes. Same starting point, altogether different deductions (with the sole intersection of a country practitioner who walks a great deal). How do two people come out so differently when faced with an identical problem?

  Watson has made two correct deductions: that the stick belongs to a country practitioner and that that practitioner does much of his visiting on foot. But why elderly and well esteemed? Whence came this picture of the conscientious and dedicated family practitioner? Not from any actual observation. It came instead from a fabrication of Watson’s mind, of his immediate reaction that the stick was just such “as the old-fashioned family practitioner used to carry—dignified, solid, and reassuring.”

  The stick itself is no such thing, other than solid. It is just an object that carries certain signs. But to Watson, it at once has a story. It has brought up memories that have little bearing on the case at hand and instead are stray pieces of attic furniture that have become activated by virtue of some associative memory processes of which Watson himself is hardly aware. Ditto the local hunt. So focused has Watson become on his imagined solid and dignified country practitioner that it seems only logical to him that the walking stick was the gift of a hunt, to whose members Dr. Mortimer has, naturally, given some surgical assistance. Watson doesn’t actually have any solid, logical steps to show for these deductions. They stem from his selective focus and the doctor that exists in his imagination. As a reassuring and elderly family man, Dr. Mortimer would naturally be both a member of a local hunt and ever ready to give assistance. Surgical? But of course. Someone of such stature and refinement must clearly be a surgical man.

  Watson fails to note entirely the M.R.C.S. appended to Mortimer’s name (something that the man himself will later point out in correcting Holmes when the latter addresses him as Doctor: “Mister, sir, Mister—a humble M.R.C.S.”)—an addition that belies the stature Mortimer has assumed in Watson’s hyperactive mind. And he makes no note, as we’ve already discussed, of the sheer fact of the stick having been left in the visiting room—minus so much as a visiting card. His memory in this instance is as mindlessly selective as his attention—after all, he did read the M.R.C.S. when he first looked at the stick; it was just overshadowed completely by the details his mind then supplied of its own accord based on the nature of the stick itself. And he did recognize at the very beginning that the stick’s owner had left it behind on the prior evening, but that, too, slipped his mind as an observation or fact worthy of note.

  Holmes’s version, in contrast, comes from an entirely different thought process, one that is fully aware of itself and of its information, that seeks to incorporate all evidence and not just selective bits, and to use that evidence as a whole, rather than focusing on some parts but not others, coloring some more brightly, and others in a paler hue.

  First, the man’s age. “You will observe,” he tells Watson, after having convinced the doctor that the most likely meaning of C.C.H. is Charing Cross Hospital and not Something Hunt (after all, we are talking about a doctor; isn’t it most logical that he would receive a presentation from a hospital and not a hunt? Which of the two Hs is the more likely, given the objective information and not any subjective version thereof?), “that he could not have been on the staff of the hospital, since only a man well-established in a London practice could hold such a position, and such a one would not drift to the country.” (We know, of course, that drift to the count
ry the man did, based on the indications of the stick, the very ones that Watson so eagerly noted and grasped.) Fair enough. Someone so well established as to be a staff member would hardly be expected to up and leave—unless, of course, there were some unforeseen circumstances. But there are no such circumstances that one could grasp from the evidence of the stick, so that is not an explanation to be considered from the available evidence (indeed, considering it would entail the precise fallacy that Watson commits in creating his version of the doctor, a story told by the mind and not based in objective observation).

  Who, then? Holmes reasons it out: “If he was in the hospital and yet not on the staff he could only have been a house-surgeon or a house-physician—little more than a senior student. And he left five years ago—the date is on the stick.” Hence, “a young fellow under thirty” to Watson’s middle-aged practitioner. Note also that while Holmes is certain about the age—after all, he has exhausted all options of his former position, until only one reasonable age alternative remains (remember: “It may well be that several explanations remain, in which case one tries to test after test until one or other of them has a convincing amount of support”)—he does not go as far as Watson in necessitating that the man in question be a surgeon. He may just as well be a physician. There is zero evidence to point in either direction, and Holmes does not deduce past where the evidence leads. That would be just as fallacious as not deducing far enough.

  What of the man’s personality? “As to the adjectives,” says Holmes, “I said, if I remember right, amiable, unambitious, and absent-minded.” (He does remember right.) How could he have possibly deduced these characteristics? Not, it turns out, in the mindless fashion that Watson deduced his own set of attributes. “It is my experience,” says Holmes, “that it is only an amiable man in this world who receives testimonials, only an unambitious one who abandons a London career for the country, and only an absent-minded one who leaves his stick and not his visiting-card after waiting an hour in your room.” Each trait emerges directly from one of the observations (filtered through the time and space of imagination, even if only for a span of some minutes) that Holmes has made earlier.

  Objective fact, to a consideration of multiple possibilities, to a narrowing of the most likely ones. No extraneous details, no holes filled in by an all too willing imagination. Scientific deduction at its best.

  Finally, why does Holmes give Dr. Mortimer a dog, and a very specific one at that? We’ve already discussed the teeth marks that Watson has missed. But the marks—or rather, the distance between them—are quite specific, “too broad in my opinion for a terrier and not broad enough for a mastiff.” Holmes may well have gotten to a curly-haired spaniel on his own, following that logical train, but he has no opportunity to do so, as the dog in question appears at that moment alongside its owner. And there, the deductive trail comes to an end. But wasn’t it a clear one as far as it went? Didn’t it make you want to say, Elementary? How could I not have seen that myself? That is exactly what deduction at its best, of course, is meant to do.

  5. Learn—From Your Failures Just as You Do from Your Successes

  In observing Watson’s fallacies in this particular instance, Holmes learns ever more about the pitfalls of the thought process, those moments when it is easy to go astray—and precisely in which direction the false path usually lies. From this encounter, he will take away the power of stereotype activation and the overwhelming influence an improper initial frame can have on the inferences that follow, as well as the error that is introduced when one fails to consider every observation and focuses instead on the most salient, recent, or otherwise accessible ones. Not that he doesn’t know both of these things already, but each time serves as a reminder, a reinforcement, a new manifestation in a different context that ensures that his knowledge never goes stale.

  And if Watson is paying close attention, he should take away much the same things, learning from Holmes’s corrections to identify those moments where he went wrong and to learn how better to go right the next time around. Alas, he chooses the other route, focusing instead on Holmes’s statement that he is not “entirely wrong in this instance. The man is certainly a country practitioner. And he walks a good deal.” Instead of trying to see why it was precisely that he got these two details right and the rest altogether wrong, Watson says, “Then I was right,” forsaking the opportunity to learn, and instead focusing once more only selectively on the available observations.

  Education is all well and good, but it needs to be taken from the level of theory to that of practice, over and over and over—lest it begin to gather dust and let out that stale, rank smell of the attic whose door has remained unopened for years.

  Any time we get the urge to take it easy, we’d do well to bring to mind the image of the rusted razor blade from The Valley of Fear: “A long series of sterile weeks lay behind us, and here at last was a fitting object for those remarkable powers which, like all special gifts, become irksome to their owner when they are not in use. That razor brain blunted and rusted with inaction.” Picture that rusted, blunted razor, the yucky orange specks peeling off, the dirt and decay so palpable that you don’t even want to reach out to remove it from its place of neglect, and remember that even when everything seems wonderful and there are no major choices to be made or thoughts to be thought, the blade has to remain in use. Exercising our minds even on the unimportant things will help keep them sharp for the important ones.

  Time to Keep a Diary

  Let’s take a quick break from Mr. Mortimer. A good friend of mine—I’ll call her Amy—has long been a migraine sufferer. Everything will be going just fine when out of the blue, it hits her. Once, she thought she was dying, another time, that she’d gotten the terrible Norovirus that had been going around. It took some years for her to learn to discern the first signs and run for the nearest dark room and a nice dose of Imitrex before the I’m-about-to-die/I-have-a-horrible-stomach-flu panic set in. But eventually, she could more or less manage. Except when the migraines struck several times a week, putting her behind work, writing, and everything else in a steady stream of pain. Or when they came at those inopportune times when she had neither a dark, quiet room nor medicine to fall back on. She soldiered on.

  A year or so ago, Amy switched primary care doctors. During the usual getting-to-know-you chat, she complained, as always, about her migraines. But instead of nodding sympathetically and prescribing more Imitrex, as every doctor before her had done, this particular physician asked her a question. Had Amy ever kept a migraine diary?

  Amy was confused. Was she supposed to write from the migraine’s point of view? Try to see through the pain and describe her symptoms for posterity? No. It was much simpler. The doctor gave her a stack of preprinted sheets, with fields like Time Started/Ended, Warning Signs, Hours of Sleep, what she’d eaten that day, and the lot. Each time Amy had a migraine, she was to fill it in retroactively, as best she could. And she was to keep doing it until she had a dozen or so entries.

  Amy called me afterward to tell me just what she thought of the new doctor’s approach: the whole exercise was rather absurd. She knew what caused her migraines, she told me confidently. It was stress and changes of weather. But she said she’d give it a shot, if only for a laugh and despite her reservations. I laughed right along with her.

  I wouldn’t be telling the story now if the results didn’t shock us both. Did caffeine ever cause migraines? the doctor had asked Amy in their initial conversation. Alcohol? Amy had shaken her head knowingly. Absolutely not. No connection whatsoever. Except that’s not the story the migraine diary told. Strong black tea, especially later in the day, was almost always on the list of what she’d eaten before an attack. More than a glass of wine, also a frequent culprit. Hours of sleep? Surely that wasn’t important. But there it was. The number of hours listed on those days when she found it hard to move tended to be far below the usual amount. Cheese (cheese? seriously?), also on the list. And, yes, she had b
een right, too. Stress and changes in weather were surefire triggers.

  Only, Amy hadn’t been right entirely. She had been like Watson, insisting that she’d been correct, when she’d been correct only “to that extent.” She’d just never taken notice of anything else, so salient were those two factors. And she certainly never drew the connections that were, in retrospect, all too apparent.

  Knowing is only part of the battle, of course. Amy still gets migraines more often than she would like. But at the very least, she can control some of the trigger factors much better than she ever could before. And she can spot symptoms earlier, too, especially if she’s knowingly done something she shouldn’t, like have some wine and cheese . . . on a rainy day. Then she can sometimes sneak in the medicine before the headache sets in for good, and at least for the moment she has it beat.

  Not everyone suffers from migraines. But everyone makes choices and decisions, thinks through problems and dilemmas, on a daily basis. So here’s what I recommend to speed up our learning and help us integrate all of those steps that Holmes has so graciously shown us: we should keep a decision diary. And I don’t mean metaphorically. I mean actually, physically, writing things down, just as Amy had to do with her migraines and triggers.

  When we make a choice, solve a problem, come to a decision, we can record the process in a single place. We can put here a list of our observations, to make sure we remember them when the time comes; we can include, too, our thoughts, our inferences, our potential lines of inquiry, things that intrigued us. But we can even take it a step further. Record what we ended up doing. Whether we had any doubts or reservations or considered other options (and in all cases, we’d do well to be specific and say what those were). And then, we can revisit each entry to write down how it went. Was I happy? Did I wish I’d done something differently? Is there anything that is clear to me in retrospect that wasn’t before?