The temptation to form premature theories upon insufficient data is the bane of our profession.
- Valley of Death
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts.
- A Scandal in Bohemia
It is a capital mistake to theorise before one has data. It biases the judgement.
- A Study in Scarlet
My name is Sherlock Holmes. It is my business to know what other people don't know.
- The Adventure of the Blue Carbuncle
On the contrary, Watson, you can see everything. You fail, however, to reason from what you see. You are too timid in drawing your inferences.
- The Adventure of the Blue Carbuncle
No, no: I never guess. It is a shocking habit destructive to the logical faculty. What seems strange to you is only so because you do not follow my train of thought or observe the small facts upon which large inferences may depend.
- The Sign of Four
Most people, if you describe a train of events to them, will tell you what the result would be. They can put those events together in their minds, and argue from them that something will come to pass. 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. This power is what I mean when I talk of reasoning backwards, or analytically.
- A Study in Scarlet