Ignore hunches and review the facts out loud.
"Holmes tells Watson everything—something that occurs with great regularity throughout the Holmes canon (and you thought it was just a clever expository device!). As he tells the doctor before he delves into the pertinent observations, 'nothing clears up a case so much as stating to another person.' It's the exact same principle we've seen in operation before: stating mindfulness. It forces you to consider each premise on its logical merits and allows you to slow down your thinking so that you do not blunder. It ensures that you do not let something that is of real significance go by simply because it didn't catch your attention enough or fit with the causal story that you have (subconsciously, no doubt) already created in your head. It allows you to confirm that you've actually understood, not just thought you understood."
Reprinted by arrangement with Viking, a member of Penguin Group (USA) Inc., from
Mastermind: How to Think Like Sherlock Holmes. Copyright © 2013 by Maria Konnikova.