I hold that this is the translation of "Let us" not "Let's." In modern English we use "Let's" to make a suggestion (cohortative modal) whereas we use "Let us" to ask for permission (suprahortative modal). Since my boss has been in Taiwan longer and because the public schools teach it the way he argues, he refuses to even listen to what I have to say. I contend that they are merely mistaking the two.
I would like to hear from fluent and literate speakers of Chinese on this issue. Can "讓" be used to make a suggestion ever in any possible context? If so, how frequently? I've asked native speakers here the same question and they say it can't. Is it true that 讓 is only used to ask for permission? Also, does anyone have a link or source they could share that would prove/settle the issue definitively? Thanks a bunch.
Your understanding of the word, 讓, appears to be better than your boss, though he may lived in Taiwan longer than you. I am a native speaker of Chinese.
I use this word only in the situation when asking for permission, a plea, or as some posters mentioned, in a formal statement, like a presidential address to the nation:
So, some examples of the usage of 讓 that I would use and their English translation:
"讓我們 jie hun ba"
"Let us get married, John!" ----- I can imagine an urgent situation that a marriage would resolve.
"讓我們 yi qi..... "
"Let us join hands and fight the drunk driving!"
But if I hear:
"Let's get married, John", ---- This would sound to be more cheerful and pleasant suggestion, or a simple flirt. So, I would not use "讓" here.