If you have studied Thai, you might know that to be polite one must add khráp/khâ at the end of a sentence: if you are a man, you use khráp, and if you are a woman, you use khâ. The words have changed quite a bit in the past. For instance, khráp is from khɔ ráp "request to receive," and khâ is from khâa which is an old term for "slave, servant" from which derives the now out of use "formal I/me." Moreover, what many Thai beginners do not know is that these are not the only ones people use (check your dictionary for more). In general, khráp and khâ are used by inferior to superior. Thus, it is unnecessary to employ them when speaking to close friends. Additionally, these words are not used in Royal Thai (since it has its own system). Interestingly, these two words can also be used in other context. In particular, they can be used to say "yes."
Other Southwestern Tai languages also have a similar system of expressing politeness and saying "yes." According to Hartmann, many Tai languages tend to use words for formal "I/me" or "you" at the end of a sentence to indicate politeness, or they can also mean "yes."
In Lao, khanɔɔy " formal I/me" and câw "formal you" or "lord/master" can also mean "yes." In a very formal speech such as when speaking to a king, khanɔɔy can even be used at the end of a sentence--just like Thai--to indicate politeness.
In Northern Thai, what is equivalent to Thai khráp and khâ are kháp and câw respectively, but the latter is used only by females. In this language, the equivalents can be used exactly the same as in Thai. Interestingly, historically câw was used by both genders, which suggests that kháp is probably borrowed from Thai khráp since most Northern Thai people are bilingual in Northern Thai and Thai.
In Shan, khâa "formal I/me" or "slave" can also be used to indicate politeness when added at the end of a sentence. Unlike Modern Thai, khâa can be used by both genders. Interesting, to say "yes" khâa is often used with ʔɤ as in ʔɤ khâa.
And finally, in Tai Lue, according to Hartmann, khɔy³ "formal I/me" can mean "yes," but it cannot be placed at the end of a sentence to indicate politeness.
Thus, from what we have seen, in all Southwestern Tai languages discussed here, formal first or second personal pronouns can be used in many contexts. In particular, the "formal I/me" or "formal you" can either or both mean "yes", and they can be used to indicate politeness. The main difference among these Tai languages is that in Lao and Tai Lue, it is not common to use these formal pronouns at the end of a sentence like in Thai and Shan to indicate politeness.
What I really want to know from Lao and Tai Lue speakers is: if I start to use khanɔɔy (or khɔy³ in Tai Lue) at the end of every sentence, would I sound weird? If you know the answer please respond to this blog.
Also please, if you speak another Tai language such as Tai Dam etc., please tell us about how politeness works in your language! We are desperate to know!
I have just heard khɔy³ being used in Tai Lue epic films.