Where does “avoir raison” come from?

avoir raison (French) comes from French raison, from Old French reson, from Latin ratiō, from Latin -tiō, from Latin dissertātiō, from Latin dissertus, from Latin disserere, from Latin dis- — small stone, pebble; gravel, rubble.

avoir raison (French): to be right; to be correct

Definitions

to be right; to be correct

Ancestry of “avoir raison”, step by step

avoir raison traces back through two separate lines of ancestry.

via French raison

Step	Language	Word	Meaning
1	French	raison	reason; common difference; common ratio
2	Old French	reson	logic, logical reasoning
3	Latin	ratiō	reason, reasoning, explanation, ground, motive, rationality, rationale, purpose
4	Latin	-tiō	tion, -ation, -ing
5	Latin	dissertātiō	(spoken) dissertation, discourse, disquisition
6	Latin	dissertus	arranged, disposed; explained
7	Latin	disserere	second-person singular future passive indicative...
8	Latin	dis-	asunder, apart, in two; reversal, removal;...
9	Latin	calceus	shoe
10	Latin	calx	limestone; chalk; the finish line
11	Ancient Greek	χάλιξ	small stone, pebble; gravel, rubble

via French avoir

Step	Language	Word	Meaning
1	French	avoir	to have; to own; to possess; to get
2	Middle French	avoir	to have
3	Old French	avoir	to have; to exist; possession; good
4	Latin	habēre	goods, capital, investment

Every word from Ancient Greek χάλιξ →Every word from Latin -tiō →Every word from Latin dis- →