ratiocination

ra•ti•o•ci•na•tion (rash-ee-oh-suh-NEY-shuhn)  n

Definition:
1. reasoning, conscious deliberate inference; the activity or process of reasoning
2. thought or reasoning that is exact, valid and rational
3. a proposition arrived at by such thought

ratiocinate verb; ratiocinative, ratiocinatory adjective

Origin:
1520s, from L. ratiocinationem (nom. ratiocinatio) "a reasoning," from ratiocinatus, pp. of ratiocinare "to calculate, deliberate," from ratio + -cinari, which probably is related to conari "to try"

Related:
Synonyms: argumentation, deduction, dialectic, induction, inference, logic, rationality, reason
Related Words: ratio, rational, ration, reason, reasonable

Sentence Examples:
• Let it be said that Poe invented or perfected--more exactly, perfected his own invention of--the modern short story; that is his general and supreme achievement. He also stands superlative for the quality of three varieties of short stories, those of terror, beauty and ratiocination.

• Of course, no intelligent person to-day supposes that, outside of Sir Conan Doyle's interesting novels, detectives seek the baffling criminal by means of analyzing cigar butts, magnifying thumb marks or specializing in the various perfumes in favor among the fair sex, or by any of those complicated, brain fatiguing processes of ratiocination indulged in by our old friend, Mr. Sherlock Holmes.

• One speaks of the great masses of simple men, and it is of them, of course, that the ensuing treatise chiefly has to say. The higher and more delicately organized tribes and sects of men are susceptible to no such ready anatomizing, for the body of beliefs upon which their ratiocination grounds itself is not fixed but changing, and not artless and crystal-clear but excessively complex and obscure. -The American Credo, George Jean Nathan, H. L. Mencken, 1920

The Storyline
...her ratiocination, on the other hand, was less solid. "Remember that time when you were ten and you didn't get the magic set you wanted for your birthday, you were such a child about it."

Why This Word:
More than a fancy word for reasoning, ratiocination is more specific than its synonyms.  Most synonyms refer to an expression or quality of rational thought, but not specifically to the process of thinking rationally. Reasoning  refers to both a use and instance of rational thought, as does ratiocination. But whereas reasoning, in common use, can be specious, flawed, even irrational, ratiocination is specifically rational thought and reasoning. It begs the question of how we can expect people to learn to ratiocinate, if they don't know the word for it.

Sources: Wiktionary, Online Etymology

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