Showing respect in English usually just means inserting the word "sir" or "ma'am" somewhere into the sentence. In most other languages, however, there is some additional grammatical work involved in displaying an appropriate level of resepect. Perhaps the most common way of doing this is by use of the T-V distinction.
T-V doesn't mean television
Subject nouns are universally understood to occur in the 1st person, 2nd person, and 3rd person, each in singular (I, you, he/she) and plural (we, you [all], they). Naturally, when you are addressing someone, you are using the 2nd person, so that is where such displays of respect typically occur.
In some cases, the 2nd person pronoun is augmented with an additional word, like "sir" in English, or "pan" in Polish. To me, this gives the impression of maintaining grammatical order while showing formality. You are talking directly to someone, but addressing them with respect.
In other cases, the 2nd person pronoun is replaced with a 3rd person pronoun, like "Usted" in Spanish, or "Lei" in Italian. I think of it as something akin to saying "Would the gentleman like some tea?" To me, this feels like a removal of direct personal connection, as if you're never talking directly to someone, but rather talking to the side with the intent of them hearing it!
But in the case of the t-v distinction, the 2nd person pronoun is made plural, even when addressing a single person. To me, this is perhaps the most logical of the three methods — even if it's not the most convenient — because you maintain the ability to lexically parse the 2nd person, while showing appropriate deference to your subject.
Examples of the t-v distinction
It most likely started in Rome, with the Latin pronouns tu and vos, but these days it can be seen in many languages throughout the world.
I first learned the t-v shift in Spanish with tú and vosotros, but I understand that vosotros is considered quite archaic these days. It makes me wonder about the books I was learning from in school!
When I had French class in school, vous was used so regularly to address people in the 2nd person that I wasn't sure whether or not tu was actually used at all! I have come to learn that they are both used, and that failure to make the appropriate distinction can be a matter of great social offense. Interestingly, when using the plural form vous to address a single person, one still uses singular forms for adjectives.
Russian makes a very clear distinction. Children, family members, and friends may be called ты. Almost everyone else is вы. There is also an additional level of respect shown through use of patronymics in address.
Ukrainian appears to be much less formal, favoring ти generally, though still using ви when addressing officials or writing documents.
I haven't learned any Czech yet, but it appears to have an interesting twist. In addition to the typical t-v usage, Czech also combines the ty and vy in a third condition for plural groups, some of whome are addressed formally and others not.
Several other languages uphold a t-v shift even in spite of those words not beginning with a T or a V sound. It appears that Mandarin, for instance, usis ni and nin — the singular and plural forms of the 2nd person — to show deference, based on the age of the person to whom you are speaking.
This also reveals a fun little observation that I enjoy pointing out to Americans when talking about those from the south. People tend to find humor in the southerner's use of the term "y'all". After spending some time in the south, one find that a waitress, for example, might address a single patron as y'all even though she would never do that with a friend. So it sounds funny, but it's actually a t-v distinction!
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