WHAT IS REASONING

Reason 
Noun
1. a basis or cause, as for some belief, action, fact, event, etc.: the reason for declaring war.
2. a statement presented in justification or explanation of a belief or action.
3. the mental powers concerned with forming conclusions, judgments, or inferences.
4. sound judgment; good sense.
5. normal or sound powers of mind; sanity.
6. Logic. a premise of an argument.
7. Philosophy.
a. the faculty or power of acquiring intellectual knowledge, either by direct understanding of first principles or by argument.
b. the power of intelligent and dispassionate thought, or of conduct influenced by such thought.
c. Kantianism. the faculty by which the ideas of pure reason are created.

Verb (used without object)
8. to think or argue in a logical manner.
9. to form conclusions, judgments, or inferences from facts or premises.
10. to urge reasons which should determine belief or action.

Verb (used with object)
11. to think through logically, as a problem (often fol. by out).
12. to conclude or infer.
13. to convince, persuade, etc., by reasoning.
14. to support with reasons.

Idioms
15. bring (someone) to reason, to induce a change of opinion in (someone) through presentation of arguments; convince: The mother tried to bring her rebellious daughter to reason.
16. by reason of, on account of; because of: He was consulted about the problem by reason of his long experience.
17. in or within reason, in accord with reason; justifiable; proper: She tried to keep her demands in reason.
18. stand to reason, to be clear, obvious, or logical: With such an upbringing it stands to reason that the child will be spoiled.
19. with reason, with justification; properly: The government is concerned about the latest crisis, and with reason.

Synonyms:
1. purpose, end, aim, object, objective. Reason, cause, motive are terms for a circumstance (or circumstances) which brings about or explains certain results. A reason is an explanation of a situation or circumstance which made certain results seem possible or appropriate: The reason for the robbery was the victim's display of his money. The cause is the way in which the circumstances produce the effect, that is, make a specific action seem necessary or desirable: The cause was the robber's extreme need of money. A motive is the hope, desire, or other force which starts the action (or an action) in an attempt to produce specific results: The motive was to get money to buy food for his family. 2. excuse, rationalization. 3. understanding, intellect, mind, intelligence. 10. persuade.