Sherlock Holmes Inductive Reasoning

The Adventures of SHERLOCK HOLMES By Sir Arthur Conan Doyle

Sherlock Holmes' Principles of Inductive Problem Solution COMPILED BY IKE SWEESY from The Complete Sherlock Holmes Sir Arthur Conan Doyle, Dorset Press, Doubleday & Co., Inc. Garden City, NY 1988. The basis of Sherlock Holmes' success is his "habit of observation and inference which [he] had already formed into a system." The Science of Deduction & Analysis OBSERVATION and INFERENCE- the practice of investigating a problem by observing every small detail then making educated inferences as to cause. It is reverse cause and effect (pg 895). Doyle specifies the system in at least three places in his adventures; the one quoted above on pg. 375 and also pp.23 and 204. While observation and inference are the two pillars of Holmes' problem solution edifice, some foundation stones that they stand upon must be first established. pp. 317,349,484,884 1. Develop And Train Your Memory For Principles, Details And People. pg. 17,176,177, 435, 484,1094. 2. Don't Burden Your Mind With Small, Unimportant Matters. pg. 21. Einstein thought this too. (but research now disputes the idea of wasting space in your mind) 3. Have Regular Habits To Train And Discipline Your Mind. Especially be an early riser. Doyle was not consistent here in describing Holmes. Sometimes he was praised for regular habits and sometimes derided for irregular ones. pg. 20,382,426 4. Know Your Own Faults And Limitations. pg. 19 (see also Sun Tzu) 5. Have Wide Ranging Studies That Give You Perspective And Breadth Of Understanding To Correlate Facts. Holmes had amassed a wide range of out-of-the-way knowledge. pp. 16,91,126,134,*225, *776,777,807,907,913,*914,1048,1090,1094,1096.

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6. Be Well Read In Relevant Historical Studies. Whatever your area of interest, be well read to give you easy familiarity with historical examples. pp. 29,176,294,777,807. 7. Be Imaginative, Creative, Innovative. pg. 344. 8. Help Others And They Will Help You. Holmes had quite a collection of people who were very willing to help him because he had helped them. pp. 106,117. THE METHOD 9. State The Problem Clearly. Without a clear understanding and statement of the problem, you will not know what you are after, nor how to proceed with the investigation. pg. 236. 10. Delineate Boundaries Of Investigation To That Which Is Relevant. pg. 546. (however, S.H. assumed every detail was relevant until eliminated)(also,‘think outside the lines’, see #11) 11. No Preconceived Solutions Or Answers With Incomplete Data. This is very tempting to do since we just can't wait to find a solution. Nevertheless, Holmes tells us to never guess, it is destructive to logic. You will tend to see data in light of your theory and you may even twist the data unconsciously. In addition, emotions will cloud your reasoning. pp. 27,84,93,*96,*322,163,407, 615,642,*657,779,789,876,895,1030,1039. cp. 1038 (see #10) 12. Observation Of Detail. This was second nature to Sherlock Holmes and usually ignored by most of the human race. He had a naturally quick mind but he commented that "I see no more than you, but I have trained myself to notice what I see." The key points are training (hard work) and actually paying attention to what you see. Two aspects of this are: a. Observation of details while they happen which takes diligent training. This is paying attention to your surroundings. pp.312,317,424 b. Observation of details of what has already happened and left indications of its passage. For instance, taking the time to look for footprints or ashes. Holmes was a master of investigating the scene minutely for details. pp. 24,126,131,*162,191,196,214,238,509,519,987,1000. 13. First Hand Examination Of The Subjects Or Location. (Touch it, Handle it!!) This is a corollary of 12. but expresses the valuable point of not relying upon what others have discovered or said about something or someone. "Measuring, comparing, examining." pp. 32,*112,176,*803,873,1114. 14. Systematic And Accurate Examination Of All Details, However Small. "Never trust general impressions, but concentrate upon details." Pg. 23,93,131,194,*261,1072,1091. 15. Identify What You Know And Make The Most Of It. pp. 549,960. 16. Be Able To Discern The Incidental From The Vital Facts. pp. 335,407,415,549.

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17. Inference From Observed Details. 83,167,246,895.

Reason backwards from effect to cause.

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18. Develop The Power Of Concentration. Listening with attention and concentration without distraction are learned skills. pg. 193,211,259. 19. Expect The Truth But Interpret It. Assume what is said is true, then find out what it is true of. This is a very important principle. Most people will tell the truth as they see it from their mental and observational perspective. Understand the individual to get at the truth. pg. 207,213. 20. Separate The Facts From The Theories, Surmises, Guesses. This is similar to #11 but others may have already begun guessing and you must ignore everything but the facts. pg. 335. 21. Find The Line Of Least Resistance To Begin Every Investigation. A common thread of meaning. An orderly, chronological arrangement. pg. 391,392,485. 22. Diligence And Tirelessness In Investigation. One gets tired with puzzling and difficult problems but diligence yields fruit. pp. 31,119,548,643,1091. 23. The Bizarre Is The Easiest, The Commonplace - The Most Difficult. pp. 50,83,183,191,1108. 24. Don't Overlook The Simple For The Complex. Many times the simple explanation is the best. pg. 136. 25. Always Look For An Alternative Explanation And Provide For It. Test every explanation. pp. 402,567,570. 26. Don't Ignore The Possibility Of Coincidences. pg. 628,1012. 27. Put Yourself In The Other's Place And Imagine What He Would Do. pp. 395,1121. 28. Rearrange The Facts And Details, Look From Every Point Of View. pg. 120,240.(see also, The Art of Clear Thinking, Rudolf Flesch) 29. Use Graphic Means To Visualize The Facts And Circumstances; Maps, Drawings, Diagrams etc. pp. 451,545,610,925. 30. Discuss The Details With Another Person.

pp. 233,336,800,960,1071.

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31. WHEN STYMIED, FRUSTRATED OR DEPRESSED, DO SOMETHING PHYSICALLY STRENUOUS Or MENTALLY ABSORBING And/Or COMPLETELY UNRELATED. Detach yourself from the problem. pp. 135,198,*929,955,984. 32. Account For Every Point Or Your Theory Is Not Satisfactory. "An exception disproves the rule." pg. 96,120,323,359,568. 33. Eliminate All Other Factors Or Possibilities And The One Which Remains Must Be The Truth, However Unlikely. pp. 92,111,315,529,621,926,1011. (however, this assumes that you know all the possibilities) QUESTIONS Who? What? When? Where? Why? How? How much? How many? What kind of? From which direction?

*by Ike Sweesy, [email protected]. www.Company-V.Com, www.FighterPilots.Net See also some good quotes of Sherlock Holmes' as compiled by Jock McTavish demonstrating many of these Principles of Sherlock Holmes:

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