Wikipedia:You have a right to remain silent

If an editor has addressed you with a query or comment, you should not feel an obligation to answer. Never forget that you have a right to remain silent. That's often the best option, especially when things are getting hot in a content discussion. It's well known that responding to trolls and vandals is a bad idea, and that editors should be careful not to fall victim to baiting. But not all undesirable talk page behavior falls into either of these categories. Sometimes editors acting in perfectly good faith can be problematic and responding to them is unproductive.

Not responding is a good idea when answering a talk page post or query will be stressful for you and unproductive for people following the discussion. Perhaps an editor is misconstruing what you've just said, innocently or otherwise. But that's not the only situation in which simply letting the matter rest is a good idea.

Some rules of thumb:

Indeed:
 * If the effect is to unnecessarily prolong an already overlong discussion, don't respond.
 * If a request for additional evidence or explanation strikes you as unnecessary, don't respond.
 * If the comment directed to you is hostile, don't respond.
 * If you have nothing to say that you haven't already said in the very recent past, don't respond.
 * If you simply don't feel like responding, for any or no reason, don't respond.

Keep the reader of the talk page in mind in such situations. By enlarging a fruitless or redundant discussion in which all essential points have already been made, you detract from understanding. You do not add to it. If you've cited a particular policy or guideline and don't wish to go into more detail, don't.

There is little downside to remaining silent. If you later realize that you have to add something you hadn't thought of earlier, by all means do so. But don't turn it into an argument with another editor. And never proclaim that you are leaving a discussion or refusing to respond to another editor. It isn't necessary and usually will be counterproductive.