ratiocination

noun3

1. •
   Reasoning, conscious deliberate inference; the activity or process of reasoning.

   • He'd run in Debt by Disputation, / And pay with Ratiocination. / All this by Syllogism, true / In Mood and Figure, he wou'd do. — 1663
2. •
   Thought or reasoning that is exact, valid and rational.
3. •
   A proposition arrived at by such thought.