Ratiocination / rash-ee-ah-suh-NAY-shun; rash-ee-oh- / noun
The process of logical reasoning.
For all their vaunted powers of rationcination, grand masters of chess tend to be a skittery lot.
-- "People", Time, October 26, 1987
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.
-- Maxim Jakubowski, "A beginner's guide to crime fiction", The Guardian, October 29, 1999
Anticipation Sir Arthur Conan Doyle by more than 20 years, an American physician named John Babbington Williams was scribbling stories extolling the fictional exploits of James Brampton, a New York detective with uncanny gifts of observation and ratiocination.
-- Marilyn Stasio, "Guilt's Companion", New York Times, December 26, 2008