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The Science of Deduction
Transcript of The Science of Deduction
Let's see how good your observations are:
From my observations, I deduce everything. For example, from the way my partner holds himself, I can tell he is a disciplined man, a military man. From there, the coloration of his skin (the tanned hands, but pale wrists and neck) I can tell he has been in the Middle East--so he has been in combat in the Middle East: Afghanistan to be precise, as Afghanistan is where most of our military officials are being sent (especially the medical doctors, as my partner is an army doctor).
You observe a stain of food on your friend's shirt. From this information, deduce a possibility of what occurred.
The Process of Elimination
After I've made the deductions (stain--food--neat--?) and I've come up with theories (overslept, late, untidy...) I start eliminating the illogical or improbable. (my friend is very tidy, so the final deduction of him being untidy is illogical). I do this until I am sure of my end result. To test the last remaining theory, I let Lestrade and my partner know what I think, and I take them through the deductions (stain--food--neat--overslept).
The first rule to solving ANY problem is to first learn to OBSERVE.
Remember that our ideas must be as broad as Nature if they are to interpret Nature.
Once this skill is attained, soon you'll be able to quickly read a situation and create your theory (for example: a toothpaste stain on your friend's shirt says that he overslept).
A Presentation by
Mr. Sherlock Holmes
Dr. John H. Watson
For further research please visit my website at:
You can also visit my colleague's blog:
Observe what is not always observed.
For example, examining someone's coat to see if it is wet or dry; this seemingly mundane observation tells more than you think!
To observe, one must always have his eyes on every little detail! Leave out NOTHING.
Always, always, always be aware of what is around you.
Quick and Easy Steps to Increase Your Focus
2. Take Field Notes to focus your attention
3. Analyze what you see: You can do this in your Field Notes.
4. Form connections between what you see and what you know. Don't leave any possibility out
5. Increase your knowledge: Make sure you fill your mind with USEFUL information,
"There's a scarlet thread of murder running through the colorless skein of life, and our duty is to UNRAVEL it, ISOLATE it, and EXPOSE every inch of it." 'A Study in Scarlet'
Take a blank piece of paper and write every object located in the classroom: DO NOT LOOK AROUND.Do this from memory
Visualize the class and list every object--be specific in detail if you can.
Now look around the classroom and see how accurate you were.
Are you surprised by your list and what is actually in the room? You'll be quite surprised to find everyday items missing from your list.
Do this exercise everyday, and you'll notice less and less are missing from your list. Why? Because your memory and observation skills go hand in hand--the better your observation, the better your memory, and vice versa.
And remember: even the seemingly mundane items can be of the most importance.
How to Deduce
Again, this is all in the observations. All a deduction is is an educated guess, or a theory that has to be tested. And always be accepting of your intuition. As I've told Watson on several occasions:
"It was easier to know it than to explain why I know it. If you were asked to prove that two and two made four, you might find some difficulty, and yet you are quite sure of the fact."
Never underestimate people or circumstances. Everything is more complex than you give credit. Even gathering information from simple sources such as tabloids can be useful . This opens your mind to how people tick, and will aid you in your observations and deducing the who, what, when, where, and why.
Finally, use logic in your deductions. This will help later in narrowing down your theories from the unrealistic to the realistic.
One answer might be:
A food stain on your friends shirt logically means that he is careless. Why would he be careless when he is usually careful and neat? Logically, this means that your friend was in a hurry to get out of the house--but why? Was he on time for every class? (of course he was, he is very tidy and neat!). So he overslept.
Test your theory:
When you make these kinds of deductions you can test your theory by going to the person and asking: Did you oversleep today? (or whatever deduction you made). If you are correct,have fun with the results!
My colleague and I have just recently discovered a case, in which we have called "A Study in Scarlet"*. I'm going to give you the information we've collected to test your deductive reasoning skills.
Upon arriving at the scene of the crime, Watson and I found the body lying stretched upon the floorboards on his back,his eyes staring up at the ceiling. He was a man in his early forties. There was no wound--visible or non-visible--on the body, but there was blood spattered on the walls and floors of the flat. The word "Rache" was scratched on the wall (Rache--German for 'Revenge'). One pill box containing two pills was also found. From documents found on his body we were able to conclude that the man--Enoch--was American and in London visiting a friend.
*--"the scarlet thread of murder running through the colourless skein of life, and our duty is to unravel it, and isolate it, and expose every inch of it" (SiS, 52)
From the above information, what can you deduce?
Remember that the body has no marks, there is blood all around the body and the walls, and the German word "RACHE" is scratched on the wall.
Now that we know how the man was murdered, let's see if we can find out who did it.
Here's what I know of the murderer: To kill Enoch, a man of height, the killer must have been a tall man. Due to the footprints in the room, he had small feet and square toed boots (he had also come in a cab, since I could not find any bootprints matching that description outside the house) There was cigar ashes scattered across the room,so we can deduce that he had been smoking a cigar. He had also left behind a small box containing two pills.
Can we solve the murder?
Remember: A tall man, came from a cab, smoked cigars, and had with him a pillbox that contained two pills.
Remember that it's okay to guess. This is what deduction is all about.
A Study in Scarlet
Do you want to know how he did it?
I tested the two pills leftover in the box on an old dog. The first one did nothing to him, but that second one killed him instantly. After arresting the murderer, I questioned him.
He said that because he was dying, he wanted revenge on the men that were found murdered. So he devised a "game". He found the two men, and gave them the two pills, saying that he would take whichever pill they didn't. Both of the men had just happened to take the poisoned medicine.
I have given you great tools--tools of deductive reasoning that, with great practice, can be put to great use. (like solving crime). Deduction is a very helpful skill to have, as it improves what you observe in your day-to-day lives.
And don't be let down if The Study in Scarlet was hard for you--you're only beginners, of course. You're not expected to know everything, especially if you are not on the scene, and investigating yourself.
Thank you for your time as my colleague and I have given our presentation. I hope you use the skills we have taught you.