When someone asks a questioner about the reason for his/her question, if they in return answer "just asking" roughly meaning "for no particular reason", should that answer be considered to be a false statement?
No, because some times you will just be being curious, or have a trivial reason for asking, and to expand further as to why you were asking would serve no purpose.
For instance, imagine a competition which required some research in the library. If the librarian asked why you wanted a particular book, and you replied "just asking", then you would be giving a false statement. It would make sense to do this, because the last thing you want is some know-it-all librarian entering your competition and pulling the prize from under your feet, to mix metaphors. However, sense or not, it would be a false statement.
However, imagine if you were standing outside the library waiting for a bus. It wasn't due for half an hour. Theres a big advert next to you, for a chocolate bar. Its says its the biggest chocolate bar in the world. It doesn't however, say exactly how big it is. You've got half an hour to kill, so you pop into the library and ask for the appropriate book. When the librarian asks why, you could explain it to them, but it would be a lot easier just to reply "just asking" as the answer is of no consequence. The librarian was just being polite.
Incidently, why do you ask?
I completly agree with your point, that when someone asks a question, them replying
Whenever an individual asks a question their reason behind asking it can always be categorised as either curiousity or purpose.
For example, say someone was going camping and figured he would need to light a campfire to make the trip enjoyable for others. For this reason, he would ask how to start a campfire, and if he replied
By contrast, if someone wondered what was needed to start a campfire, him asking that question would be due to curiousity. Thus if he replied,
The only reasonable situation where,
Thus the responsive statement "just asking" is ALWAYS false.
If you disagree, I disagree (with you), so feel free to try firing some cases at me.