InvestigatorAsPhilosopher

Sherlock Holmes is depicted as both a supremely logical thinker and a supernaturally astute observer. What hidden advantage did he hold over his peers?

Consider: Holmes observed the world around him in a manner which took into account the most minor details. Those around him seldom detected the same "clues" and when they did, the evidence in front of their eyes was empty to them. Conan Doyle may or may not have consciously given Holmes an unfair leg up over his compatriots - but regardless of intent, that advantage existed.