Simply put, deduction is the art of reasoning backwards; determining a cause from observable effects. Sherlock Holmes – a brilliant fictional detective curated by Sir Arthur Conan Doyle in the 19th century revolutionized this art. Armed with deductive prowess and keen observation skills, solving the most perplexing crimes was second nature to him. Deduction, however requires a massive amount of training and a vast knowledge base. Moreover, in everyday affairs, it is more useful to follow the trail of breadcrumbs or, reason forwards. So most people are not naturally equipped with this talent. The good news is, with a little bit of patience and practice, you can pick up this exceptional skill. And I can tell you just how.
“I never guess. It is a shocking habit – destructive to the logical faculty.”
The great Sherlock Holmes never guessed! He followed a sequence of carefully thought out steps before arriving at his conclusions which were almost always accurate.
Step 1: Observation
“You see, but you do not observe.” – Sherlock once said to Watson.
The distinction is quite simple. I‘ve climbed the same flight of stairs to reach my room back at home at least a million times. Yet, I cannot say with conviction, the exact number of steps there are. Most people have a reasonably poor visual memory. This can be strengthened by simply imagining doing a task before actually doing it.
Step 2: The Rule of 3
Typically for any experimental validation, we require at least 3 observations. For deduction too, it is advised to get at least three solid facts.
Suppose a person writes with their left hand, we can safely conclude that their dominant hand is their left. There are very few who are ambidextrous so, this is unlikely.
But, if someone wears their watch on their right hand, while it is reasonable to assume that they are left handed, it is not so much a smoking gun. They may simply not be aware of watch wearing etiquette. So, observe further. Do they write with their left? Do they perform most other activities primarily with their left? This will enable you to make accurate deductions.
Step 3: Theorize and Eliminate
“It is a capital mistake to theorize before you have all the evidence. It biases the judgment.”
Sherlock believed that people tend to twist facts to suit theories rather than the other way around. So before one begins this step, be sure to have all the pertaining data. We may come up with many conjectures and theories. But once you eliminate the impossible, what remains, however improbable, must be the truth.
For instance, on wednesday morning, the quiet, reserved girl – your lab partner – seems rather sluggish and unfocused. Lined with dark circles, her eyes look tired. Clearly, she hasn’t slept enough the previous night. There may be several reasons for her sleep deprivation. She may have been out partying the night before. Or she might have been up studying. Considering her general demeanor and the fact that it is the middle of the week, we can eliminate the former possibility. But, do this with care. We shouldn’t force pieces of the puzzle where they don’t fit. Infact, it is very common to come up with more than one plausible story.
After having taken a peek into the inner workings of this mastermind, we can put this newly gained knowledge to test. Tempting as it is, to be able to solve a bank heist or murder all at once, start small. Solve simple problems like guessing a person’s dominant hand, hobbies or demeanor to build the habit of using the logical faculties and techniques to solve more complex problems. Verbalizing your theories to a friend also simulates the brain. Practice makes perfect!
– Bhavishya Viswanath