Can Sherlock Holmes Teach Us About Avalanches? – Part 2

Part 2. How Sherlock Holmes Thinks Backwards.

An example of Holmes thinking backwards can be read in A Study of Scarlet where Holmes describes the history of a watch recently acquired by Watson. After looking at the watch for just seconds, not only did Holmes accurately tell how Watson got the watch, Holmes correctly described character of the watch’s former owner, Watson’s eldest brother. Holmes had inferred his conclusions based the watch’s style, age, initials on the back, and that the watch had been recently cleaned. From this he deduced the watch had belonged originally to Watson’s father and was passed along to the oldest son. He then went on to describe the son as untidy and careless who bounced back and forth several times from success to poverty, but eventually took to drink and died. Watson was stunned that Holmes was so right, and accused Holmes of investigating his poor, unhappy brother. Holmes had not done anything of the sort.

Rather, Holmes was a keen observer and from the wear, dents, and scratches to the watch, and from these clues deduced the history of its previous owner. Holmes solved cases by using his knowledge and reasoning — often working backwards — to solve mysteries. He did this by eliminating factors, a process he called the method of exclusion, “By the methods of exclusion, I had arrived at this result, for no other hypotheses would meet the facts. (The Complete Sherlock Holmes, A Study of Scarlet, p. 69)” This statement tells Watson, and us, that facts should not be twisted to match a hypothesis. Throughout the many stories, Holmes reminds Watson of this method. The last reminder came late in Holmes’ career (The Complete Sherlock Holmes, His Last Bow, The Bruce-Partington Plans, p. 886).

After accepting Holmes’ plea that he did not investigate Watson’s brother, Watson accuses Holmes of guessing. An action that Holmes firmly denies. “No, No: I never guess. It is a shocking habit—destructive to logical facility.” (The Complete Sherlock Holmes, The Sign of Four, p. 79)

Like Holmes, doctors do the same thing when conducting the differential diagnosis (DD). Doctors use a process of exclusion and don’t guess. Before dismissing or excluding a cause the doctor must come up with a good and valid reason. The complexity of the DD depends on the chief complaint. Something that seems simple, say a productive cough (coughing up sputum or mucous), can be quite challenging to determine the cause with more than 70 possible diagnoses ranging from a simple cold to pneumonia, to abscesses, to genetic disorders, to even poisonings.

Alternatives and the Devil’s Advocate
Along the same lines as a differential diagnosis is Holmes’ use of alternative reasons or hypotheses. In Black Peter, about a grisly harpoon murder published in 1904, Holmes tells Watson, “One should always look for a possible alternative, and provide against it. It is the first rule of criminal investigation.” (The Complete Sherlock Holmes, Black Peter, p. 536) Holmes is onto something when he talks of an alternative, and his message is very important today, especially for groups. When groups stop considering alternative hypotheses and seek consensus, groups are prone to making bad decisions. This action is called groupthink, a term coined by Irving Janis in the 1960s who studied several major America foreign policy failures ranging from Pearl Harbor to the Vietnam War. Janis found that cohesive groups (actually committees in his study) prevented contradictory views causing the groups to stop critical testing, analyzing, and evaluating ideas.

Groupthink is pervasive and has bungled battles, wars, national economies, and even results in avalanche accidents. To prevent groupthink, groups should follow Holmes’ advice and always seek out alternative hypotheses. Janis also suggested another tactic, borrowed from the Catholic Church, the advocatus diaboli or devil’s advocate.

Established in the sixteenth century and employed for 400 years, the devil’s advocate was a cannon lawyer who argued against the declaration of a person being a saint. The advocatus diaboli looked for holes and mistakes in reasoning, and argued against a consensus. This is a vital member for any group that seeks to make good decisions. A devil’s advocate should propose alternative hypotheses and make sure relevant data is collected. Too often data is missed, dismissed or ignored, and Holmes knew this. [In 1983 the advocatus diaboli position was ended and the duties transferred to the promotor iustitiae.]

Early in A Study of Scarlet (p. 15) Holmes tells Watson, “It is a capital mistake to theorize before you have all the evidence. It biases the judgment.” Holmes does not tend to dismiss clues. He records and remembers data. He gives his reason to Scotland Yard inspector Lestrade as “We may come across something later which will bear upon it.” (The Complete Sherlock Holmes, The Adventures of the Six Napoleons, p. 555) As cunning and cleaver has Holmes appears he is not infallible. Like the rest of us, he too sometimes jumped to conclusions when he relied on incomplete data. Holmes revealed to Watson in The Speckled Band (p. 253), he [Holmes] had “…come to an entirely erroneous conclusion which shows, my dear Watson, how dangerous it always is to reason from insufficient data.”

For both doctors and detective sleuths answers are not found by simply collecting more data. Nor is it about collecting the right data as the “right data” can used selectively to confirm an intended result. But sometimes those results are wrong or have a bad outcome. This is known as a confirmation bias and with avalanches the results can be deadly. By collecting data that reduces uncertainty helps to reduce the affect of confirmation bias.

When it comes to collecting data, Holmes was an expert observer, and that is what we should strive to be too. In The Blanched Soldier, Holmes found himself alone as Watson had gone off “to find a wife”. Instead of Watson’s usual narration, Holmes tells the story and it starts with his meeting of Mr. Dodd. Much in the same way that Holmes had evaluated Watson’s watch, Holmes did the same in evaluating and describing Mr. Dodd who had just set down before Holmes. Mr. Dodd was stunned as Holmes described his history, based just from Dodd’s appearance. Dodd’s stated, “You see everything.” Holmes offered a simple reply, and one that’s important for all decision makers, “I see no more than you, but I have trained myself to notice what I see. (The Complete Sherlock Holmes, The Blanched Soldier, (p. 959). Wise words.

Usually Sherlock Holmes did not work alone, and whether he was with his sidekick Dr. Watson or someone else, Holmes found a great benefit to summarize a situation or case to another person. As Holmes starts his investigation into a missing racehorse and the murder of its trainer, he tells Watson, “At least I have a grip of the essential facts of the case. I shall enumerate them to you, for nothing clears up a case so much as stating it to another person, and I can hardly expect you to co-operate if I do not show you the position from which we start (The Complete Sherlock Holmes, Silver Blaze, p. 313).” Doctors and detectives are taught and seek to perfect their narratives as to the who, what, when, where, how and why of a case. The narrative communicates clearly the situation and is an action that all decision makers should practice. Not only do narratives communicate about a situation and its facts, the narrative also communicates the interpretation of the situation and facts, and that is what influences decisions. A good narrative is critical to making good decisions.

Summary — Part 2
To wrap up Part 2, Holmes thinks backwards. He starts with the problem and seeks the facts. Holmes collects data; data that reduces uncertainty, so he can make inferences to what had happened. A physician follows an identical path starting with the chief complaint and then gathers the patient’s story, physical findings and nonfindings (pertinent negatives). Armed with facts, Holmes formulates a hypothesis and seeks out alternatives too. The physician does the same when employing the differential diagnosis, a reasoned consideration, in order of likelihood, of several maladies from which a patient with these signs and symptoms might be suffering (Doctors Stories, Hunter, 1991, p. 55).” Holmes with several hypotheses to ponder now starts his method of exclusion. The doctor does the same thing by eliminating maladies based on the facts. Both the Holmes and the doctor must rule out competing hypotheses until the most reasonable explanation remains. The challenge is not to twist the data to fit the hypothesis, but rather to twist or reject the hypotheses to fit the data. Both Holmes and the doctor work from effect to cause.

At this point you might be thinking that Holmes’ methodology and the doctor’s diagnosis work well for explaining what has happened, but how can it be applied to deducing what might happen in the future. In Part 3 (next week) I’ll tell you how use this strategy — thinking from effect to cause — with avalanches.

Note: All references to Holmes can be found in The Complete Sherlock Holmes, Sir Arther Conan Doyle, first published in 1924, 1926, 1927, 1930, republished in 2009 by Barnes & Noble, Inc. New York, NY.

Thanks for reading.
Dale Atkins

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12 Responses to Can Sherlock Holmes Teach Us About Avalanches? – Part 2

  1. Tom Murphy says:

    Dale, regarding this: “When groups stop considering alternative hypotheses and seek consensus, groups are prone to making bad decisions.” How about groups reaching a consensus on what terrain to avoid for given day?

  2. Dale Atkins says:

    Hey Tom — Great question and here’s what I think. Consensus decision-making can be very effective and is certainly so when a group decides what terrain to avoid. That’s good. The problem with consensus decision-making and the test for groups is to avoid falling into the traps (or suffering the “symptoms”) that Janis documented. In avalanche accidents too often we hear of a group that decides to “go for it” even though a member (or two) did not feel good about the decision or worse, knew that it was a bad decision. Usually these members do not speak out because they did not want to upset the group, or they refrained under pressure (explicit or implied) not to talk because their views conflict. Consensus performs poorly when everyone cannot or does not talk. Basically, somebody does not challenge the group’s view.

    A challenger is key to helping groups make better decisions. A lone dissenter “gives permission” for the rest of the group to re-evaluate their position. This is practiced by such diverse groups as the US Supreme Court and by airline pilots. Though neither group calls this person the advocatus diaboli, a challenger serves the same purpose. They object or query to the true. In the Supreme Court the challenger is the dissenter and their argument goes on the record so the other justices must respond.

    A second pilot (or first officer) is now trained to challenge the pilot in command. The challenge is generally made by using the pilot’s first name followed by a quantifier to the fact. “Chris, are you going make this approach? Stay on the gauges until you see the runway.” The idea is to get the pilot’s attention to break their tunnel vision. Tunnel vision affects us in the backcountry, too.

    I am not saying a consensus agreement is bad. Groupthink doesn’t always happen. We just to be careful not to let it happen. A group that was challenged by the thinking of its individuals will make better decisions than the group that just wants to get along. The dissenter, challenger, and devil’s advocate make groups make better decisions. Seems to me, these roles can work for us when making avalanche decisions. We should try it.

  3. Mark Nelson says:

    I enjoyed this installment and the analogy to medical assessment, granted rescuers in the backcountry don’t have the luxury of a clinical setting to best monitor physiology, but we do have a unique situation to be at scenes, visualize mechanisms, and ascertain patient signs/symptoms to try and deduce life threats as well as transport & technical logistics.

    It can be a fine balance to weigh out life threats, packaging decisions, equipment supply, & the technical logistics of transport. Sufficed to maybe some other beliefs, I don’t feel the heli solves everything. In thought, I wonder if the certain rescue decisions in the heli access, swoop & scoops, lend to disregarding the hazard of the mountains such as avalanche, or create a danger that really wasn’t necessary, without taking that deductive approach to analyzing what really has happened and what could still be a problem.

    • Dale Atkins says:

      Hey Mark,
      I agree with you that a helicopter doesn’t solve everything whether it’s street medicine, wilderness medicine, or mountain rescue. The helicopter can, however, make things happen easier which becomes faster which is good for people in need, but it does come with a cost. And I don’t mean just in dollars. Its use can certainly lead to rescuers ignoring or dismissing other threats. Plus, utilizing a machine that beats the air into submission to stay aloft comes with added and different dangers for the crew, rescuers, and the subject. Flight crews and rescuers generally do a very good job of analyzing the risks, but sometimes, it seems, they too suffer some sort of psychological blindness, that sometimes leads to bad accidents. And their decision making often falls apart in their reasoning, or lack of reasoning.

      Whether dealing with airplanes or avalanches, or just about any sort of decision with a significant degree of uncertainty, it’s very important that we use a deductive approach. I think Sherlock Holmes can show us that working backwards from effect to cause will help us be better decision makers. I hope you stay tuned for Part 3. It will be posted by Thursday (Feb. 10).

  4. Brad Sawtell says:

    I find myself asking “why is this slope stable?” as opposed to asking “is this slope stable?” often. You can also change the word “stable” to “unstable”. By exercising this form of questioning, I find it easier for myself to seek more information in order to support effective decisions in order to reach positive outcomes. I guess it helps prove a hypothesis. Your thoughts Dale?

    • Dale Atkins says:

      Hey Brad,
      Great point about thinking “why” rather than “is”. I like it! To begin the question with “is” results in a decision problem that can only have a yes-no answer. Your phrasing the question with “why” turns it into a process problem that should drive one to keep looking for and asking about more clues, or as you wrote, “more information.” This is great advice. Thanks!

      In Part 3, I might touch on hypothesis testing, but I am planning a longer discussion for a future blog . We have to be careful about “proving” our hypothesis because we can easily fall under the affect of a confirmation bias. For my future hypothesis-testing blog, I’ll compare criminal trial (innocent or guilty) decisions with avalanche (stable or unstable) decisions. Here’s a hint, because (I think) it fits exactly with my suggestion of backwards thinking. When thinking about avalanches, we have to think like a prosecutor who attacks the claim of innocence. Stay tuned and thanks for reading.

      • Justin Peacock says:

        @Brad: I love your question (why is this slope stable?). I will definitely use that.

        @Dale: Excellent post!

  5. Andy Gleason says:

    Elementary my dear Atkins. Great Article Dale. Love the line ” i have trained myself to notice what i see” perfect for seeing instability instead of stability.

  6. Jeff Sparhawk says:

    Extrapolating a bit, are you suggesting that we evolve avalanche education from primarily what to observe (natural conditions) to learn how we observe what we observe?
    Essentially their are two factors for each individual at any given time and place. Factor A indicates the avalanche danger in some quasi objective manner as determined by that person. Factor B indicates the risk acceptance, experience, propensity to group think, “detailedness” and “devil’s advocateness” of individual who determined the avalanche danger of factor A. B gives a lens through which to view A or a margin of error to assign to A. The (unobtainable) goal being to view A through a perfectly clear lens.
    Learning avalanche safety skills (A) without a firm understanding of ourselves (B) may drastically alter the value of learning avalanche safety skills at all.

    This is off the top of my head and may not hold together under scrutiny.

    • Dale Atkins says:

      Jeff, I need to get a pair of glasses like yours. You have summed up nicely an indirect argument of mine. ☺ YES, I am advocating that avalanche education also include introspection. We have to have awareness of how we perceive and interpret what we see, so we can make accurate conclusions. Our lens is never clear; it’s shaded by layers of neurophysiology, experience, knowledge, emotion, self and social identities. Take neurophysiology, recent advances in neuroscience tells us that what we perceive is not a product of our eyes and ears. Perception is a product of our brain, and our brain does not take snap shots or operate like a computer, rather it’s like a giant Kitchen Aid mixer [my metaphor] that cuts in, mixes and mashes everything our senses receive. Neuroscientist Gregory Berns says perceptions “are nothing more than biological and electrical rumblings that we believe to be real.” (And he’s not alone in his thinking.) This is the root cause of why two people can look at the same evidence and draw two different conclusions. The other layers may add divergent interpretations; however, it is with these other layers that education, training, and practice can temper the interpretations and bring us into better alignment. Better understanding of ourselves means better understanding and better application of avalanche safety skills.

      Now you’ve given me an idea for another topic: emotion. Sherlock Holmes would probably say something like, “Eliminate emotion; emotional qualities are antagonistic to clear reasoning.” (Actually, the first two words are mine, but the rest are pure Holmes – The Sign Of Four) On paper and in the classroom to say, “remove emotion from decision-making” seems so logical and reasonable. Current avalanche education does not even think about emotion, but emotion (excitement/arousal) is why we do what we do in the mountains. I don’t think emotions can be separated from decision-making, but emotions can be tempered with awareness of their affects and by being analytical in reasoning. Maybe Holmes might accept that.

  7. Dale Atkins says:

    Vulcan on!

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