Sometimes, the impossible takes place: Sherlock Holmes makes a mistake. Yes, it happens. The master detective falls prey to some of the very errors he urges us to avoid. If even he falters, what chance do we mere mortals have? Well, for one, we can examine those moments when Holmes does go wrong and see what we can learn from the shortcomings of the normally infallible master--after all, it is often in the very errors and flaws of a process that we are able to discern the most about how something actually functions.

In “Silver Blaze,” one of the paragons of logical reasoning, Holmes admits to a rare lapse in judgment. In the story, a prize horse goes missing. As Holmes and Watson head to Dartmoor to help with the investigation, Holmes mentions that on Tuesday evening, both the horse's owner and Inspector Gregory had telegraphed for his assistance on the case. The flummoxed Watson responds, “Tuesday evening! And this is Thursday morning. Why didn't you go down yesterday?” To which Holmes answers, “Because I made a blunder, my dear Watson--which is, I am afraid, a more common occurrence than anyone would think who only knew me through your memoirs. The fact is that I could not believe it possible that the most remarkable horse in England could long remain concealed, especially in so sparsely inhabited a place as the north of Dartmoor.”

And there you have it. The great Holmes has made a blunder.

A failure of imagination

So, what exactly is it that has gone wrong? Holmes often touts the benefits of imagination, that quality of mind that enables one to go beyond the hard facts and envision hypothetical worlds and alternative possibilities--in fact, he demonstrates the power of imaginative thought in “Silver Blaze” itself, to great effect. But even the best imagination is a servant of its owner's mind, and that mind is necessarily subject to his unique experience and world perception. While a mind such as Holmes's is, as a rule, able to imagine even the most remote of possibilities, to see beyond the present and bring to bear a wealth of knowledge to chart out most any eventuality, there are times when it, too, becomes limited by preconceived notions.

The concept is a simple one: preconceptions blunt imagination by narrowing the sphere of considered options. We are limited by what we see. Holmes sees a horse of exceptional appearance missing in a rural area. He can imagine many alternatives, but among them, he would never include something that dealt with a remarkable horse in a heavily populated area, or with a horse that wasn't so remarkable in a sparsely populated area. After all, neither of those options corresponds with the facts--or at the very least, the facts as he sees them. For here, Holmes commits the mistake that is usually the failure of the Lestrades of the world, in taking a preconception and making it into a fact. His imagination does not extend to the possibility that either of his premises may be wrong.

True, the geography of the area is not subject to doubt. Dartmoor is, objectively, a sparsely populated locale. But a horse of remarkable appearance: is that set in stone? Holmes thinks it is--hence, the preconception--and consequently limits his imagination to a consideration of only those alternatives where that remains the case. His logic is as follows: if the horse is the most remarkable such animal in the whole of England, then how could it go under the radar in a remote area where hiding places are limited? Surely, someone would notice the beast, dead or alive, and make a report. But, it is Thursday, the horse has been missing since Tuesday, and the report has failed to come. What is it, then, that Holmes failed to take into account?

A horse couldn't remain concealed if it could still be recognized as that horse. The possibility of disguising the animal doesn't cross the great detective's mind; if it had, surely he wouldn't have discounted the likelihood of the animal's remaining hidden. The question then becomes, why didn't he consider it? Why did the man who thinks of everything not think of this?

We are limited by our experience and our habits of thought

First, there is the question of experience. Our imaginations tend to be rooted in our own knowledge. What we see isn't just what there is; what we see is also what we know. Were we to witness something that in no way fit with past schemas, had no counterpart in our memory, we would likely not know how to interpret it - or, we may even fail to see it altogether, and instead, see what we were expecting all along. Think of it as a complex version of any one of the famous Gestalt demonstrations of visual perception, whereby we are easily able to see one thing in multiple ways, depending on the context of presentation. For instance, in this example, do you see the middle figure as a B or a 13? The stimulus remains the same, but what we see is all a matter of expectation and context. A disguised animal? Not in Holmes's repertoire, however vast it might be, and so, he does not even consider the possibility.

That oversight is directly related to the second element of imaginative failure: everyone has blind spots. In our distinctive way of looking at the world, we will inevitably make the same characteristic mistake over and over. The mistake may not be a common one--and it certainly doe not have to be common to everyone--but it will be typical of us, of our thinking, of our perception. Call it a personal habit of the mind. And in “Silver Blaze,” we come across one of those habits in Holmes: a failure to imagine the possibility of disguise.

Though the detective himself is a master of concealment, he seems to discredit the extent to which others may follow suit. “The Man with The twisted Lip” comes to mind almost immediately. Does it not strike you as odd that Holmes would not consider the possibility of disguise earlier on in the story? It seems an uncharacteristic oversight on his part. Or, take “The Yellow Face.” Here, too, disguise--or a lack of consideration for its possibilities--bears directly on Holmes's failure to reach the proper solution to the mystery. The point here is not to laud the benefits of disguise, but rather to illustrate the notion that every mind has characteristic areas of shortcoming--even the greatest.

Had Holmes had the same benefit of rereading his own exploits as we do, he may have learned that he was prone to this type of error. Had he seen the whole picture, each story nicely placed back to back, he may have discerned a common problem. But give him disparate events, over many years, and the feat of analysis becomes a difficult one. In fact, it is not inconceivable that he'd fail to make the connection even if he had the whole picture, presented to him just as it is to us. Self-analysis is notoriously challenging. We don't often like to look at our own shortcomings - indeed, we may not see them even if we stare them in the face. And while normally, the failure is an adaptive one--it keeps us from getting depressed, for one--it does cause errors in thinking that we could avoid if we chose to undergo more extensive self-analysis.

The moral of the story? We are all subject to our past experiences, our preconceptions, our habitual ways of thinking. Even Holmes. But, unlike Holmes, who is doomed by his creator to relive his errors over and over, we still have the possibility of change. We don't have to keep falling for the same mistake. Some honest self-probing may set us on our way to remedying those areas where our minds are most likely to falter. And at the end of the day, that is the goal of each of these lessons, to get us one step closer to Holmes at his best and to use opportunities when he stumbles to learn how to surpass him at his own game--or at the very least, to learn what exactly the game entails.

Photo credit: The famous duck-rabbit Gestalt illusion. What do you see, a rabbit or a duck? It may depend on the animal you are more familiar with and which of the two you are expecting to see. Image courtesy of Wikimedia Commons. Originally published in Jastrow, J. (1899). The mind's eye. Popular Science Monthly, 54, 299-312.


Previously in this series:

Don’t Just See, Observe: What Sherlock Holmes Can Teach Us About Mindful Decisions

Lessons from Sherlock Holmes: Paying Attention to What Isn’t There

Lessons from Sherlock Holmes: Cultivate What You Know to Optimize How You Decide

Lessons from Sherlock Holmes: Perspective Is Everything, Details Alone Are Nothing

Lessons from Sherlock Holmes: Don’t Underestimate the Importance of Imagination

Lessons from Sherlock Holmes: Confidence Is good; Overconfidence, Not So Much

Lessons from Sherlock Holmes: The Situation Is in the Mindset of the Observer

Lessons from Sherlock Holmes: The Power of Public Opinion

Lessons from Sherlock Holmes: Don’t Tangle Two Lines of Thought

Lessons from Sherlock Holmes: Breadth of Knowledge Is Essential

Lessons from Sherlock Holmes: Don’t Decide Before You Decide

Lessons from Sherlock Holmes: Trust in The Facts, Not Your Version of Them

Lessons from Sherlock Holmes: Don’t Judge a Man by His Face

Lessons from Sherlock Holmes: The Importance of Perspective-Taking

Lessons from Sherlock Holmes: From Perspective-Taking to Empathy

Lessons from Sherlock Holmes: Why Most of Us Wouldn’t Be Able to Tell That Watson Fought in Afghanistan