This is another good one from that legendary pipe-smoking detective. Arthur Conan Doyle’s Sherlock Holmes often employed this technique and lamented that more people don’t employ it. The basic idea is that you start with the result you want, and move back in steps to where you are now. Like most things that sound simple, this one isn’t so as simple as it appears on the surface. Here are five quotes on the matter, again from that great Peter Bevelin book, A Few Lessons From Sherlock Holmes.
“The essential factor in this method consists in working back from observations of conditions to the causes which brought them about. It is often a question of deciding the doings of yesterday by the records found today. (Thomas McCrae; The Method of Zadig)
“The ideal reasoner…would, when he had once been shown a single fact in all its bearings, deduce from it not only all the chain of events which led up to it but all the results which would follow it. (Holmes; The Five Orange Pips)
“In solving a problem of this sort, the grand thing is to be able to reason backwards. That is a very useful accomplishment, and a very easy one, but people do not practice it much. In the everyday affairs of life it is more useful to reason forward, and so the other comes to be neglected.” (Holmes; A study in Scarlet.)
Every day we reason forwards. “What’s the result of this going to be?” “Can I fit these different events into my day?” And generally, we’re pretty good at this. I think that’s a positive sign we can be equally good at reasoning backwards. Every day look at a situation and trace back the steps that you think resulted in it getting to its current form. Just pick a couple things, whether its the stain on a person’s shirt or a crisis at a company. This won’t make you like Sherlock Holmes, but it’s going to make you a better thinker!