ratiocination: the process of logical reasoning or exact thinking
(Example: The adventures of Sherlock Holmes proved so popular that it became a given that mystery tales should include a sleuth who investigates a murder or other crime, and by virtue of intelligence, ratiocination and perseverance solves a case that initially seemed unsolvable. [Reference: Maxim Jakubowski, "A beginner's guide to crime fiction", The Guardian, October 29, 1999])
