No, this isn't a philosophical question. I recently read an interview transcript in German which contained the sentence, "Ja, Sie haben absolut Recht." This means "Yes, you're absolutely right," since "Recht haben" is literally "to have right" or "to have correctness". I'd intended to translate the article, but an acquaintance beat me to it. In her initial version, though, this line was rendered as "Yes, you have every reason."
What's interesting is that she was translating from the French version of the article, in which the line read, "Oui, vous avez tout à fait raison." Now, my French comprehension is pretty lousy, as it's based purely on my familiarity with other Romance languages, but I'm pretty sure both that the translation given above is a literal one and that the idiomatic meaning is, in fact, "Yes, you're right." In Spanish, it's the same thing: "Sí, tiene razón."
The American Heritage dictionary gives the etymology of "reason" as "Middle English, from Old French raison, from Latin ratio, ration-, from ratus, past participle of reri, to consider, think." So saying "You have reason" is essentially saying, "You have thought about this," and it's not a big leap in language development for this to evolve into "You're right," even when the subject under consideration isn't something that can be decided by logic.
The funny thing is that the interviewee in this case was an American, so his responses had already undergone translation into the French/German publication before we attempted to translate them back. I'm reminded of an example I read many years ago illustrating the inadequacies of computerized translations. The famous line "The spirit is willing, but the flesh is weak" had been automatically translated from English to Russian and back to English to become, "The wine is good, but the meat is terrible."