Before turning to those moral and mental aspects of the matter which present the greatest difficulties, let the inquirer begin by mastering more elementary problems. Let him on meeting a fellow-mortal, learn at a glance to distinguish the history of the man and the trade or profession to which he belongs. Puerile as such an exercise may seem, it

Strip away things that don’t count and focus on what matters - the core Eliminate possibilities - What can we exclude? - Assuming the true solution or explanation is among the considered possibilities

I fear, sir...that, interesting and indeed essential as these details are, my inquiries must go more to the root of things. (Holmes;

No one can give rules for methods of thinking but it is possible to carry certain principles into operation. One is to strive to be delivered from hasty judgments. “Men see a little, presume a good deal, and so jump to the conclusion.” How common this is needs only a little study of our mental processes. In some this is a habit, in others a fault

The larger crimes are apt to be the simpler, for the bigger the crime the more obvious, as a rule, is the motive. (Holmes;

The world is full of obvious things which nobody by any chance ever observes. (Holmes; The Hound of the Baskervilles)

Check for other possible explanations - What else can explain this?

Criticize ourselves - Have we tried to find evidence against what we believe? Why might we be wrong? What have we overlooked? What (new) information or evidence is needed to make us change our mind? When we meet a fact which contradicts a prevailing theory, we must accept the fact and abandon the theory, even when the theory is supported by great

The pressure of public opinion can do in the town what the law cannot accomplish.