“They say that genius is an infinite capacity for taking pains,” he remarked with a smile. It is founded upon the observation of trifles.” “There is nothing like first-hand evidence.” “I had,” he said, “come to an entirely erroneous conclusion, my dear Watson, how dangerous it always is to reason from insufficient data.” “Data! Data! Data!” he cried impatiently. We were simply there to observe and to draw inferences from our observations.” We approached the case, you remember, with an absolutely blank mind, which is always an advantage. You can find yourself insensibly twisting them round to suit your theories. “Still, it is an error to argue in front of your data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.”

“It is a capital mistake to theorize before one has data. “It is a capital mistake to theorize before you have all the evidence. This power is what I mean when I talk of reasoning backwards, or analytically.” There are few people, however, who, if you told them a result, would be able to evolve from their own inner consciousness what the steps were which led up to that result. They can put those events together in their minds, and argue from them that something will come to pass. Most people, if you describe a train of events to them, will tell you what the result would be. There are fifty who can reason synthetically for one who can reason analytically…Let me see if I can make it clearer. In the every-day affairs of life it is more useful to reason forwards, and so the other comes to be neglected. That is a very useful accomplishment, and a very easy one, but people do not practise it much. “In solving a problem of this sort, the grand thing is to be able to reason backwards. Simply Stated – Deduction is Reasoning Backwards Sherlock Holmes regarding his techniques and methods for solving mysteries and crimes using deductive reasoning. Gleaned from the stories of Sherlock Holmes written by Sir Arthur Conan Doyle are these quotes from Mr. Sherlock Holmes on Deduction and Deductive Reasoning

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