It sometimes happens that I am asked a question which I am uncomfortable answering for a variety of reasons (it invades my privacy, the answer may hurt the person asking, it is painful for me to discuss, it would violate a confidence etc.). I may also not feel comfortable explaining why I don't want to answer.
I remember a colleague of mine introducing me to the Far Eastern concept of Mu (sometimes translated as "unask the question"), which seems to quite aptly capture what I'm looking for.
What is the most polite way of expressing this in English?
Best Answer
Assuming you're willing to be clear that you don't wish to answer, I think the best response is probably "I'd prefer not to answer that". Anyone who asked you to explain why would in my opinion be incredibly rude; you'd be under no obligation to continue being polite if that happened.
Strictly speaking I agree with @Joseph's point below; the "most polite" form is probably "I'd rather not answer". This question reflects my belief that rather is more associated with casual speech and informality than prefer. So arguably it's more non-aggressive/acquiescent/polite. But I'd go for prefer - it's "firmer" to me, while still being polite.
If you don't even want to be so forthcoming as to actually admit that you don't want to answer, just ignore the question and start talking about something else. Sometimes people genuinely don't recognise what you mean by this, so they may ask you again. But if you repeat this "evasive tactic" and they ask a second time, you can safely assume they're being rude - so again, you're under no obligation to continue being polite. Depending on context, either tell them to "F**k off", or say something explicitly firm like "I'm sorry, but I think I've made it clear I don't want to answer that".