I feel that specific 'responding to arguments' type questions should be on-topic, but generally my vote would be to leave them for now and come back to this question after a few weeks. If they dominate the site and all end up having similar themed answers, then they probably are off topic (or at least duplicates of a more general question which covers this situation).
As an example, I don't think these questions are the same type of question:
a) What experiment can I use to show that magnets do not 'make you stronger'?
One is talking about a specific problem domain (magnets and their effectiveness) while the other is a general 'how do I counter these types of arguments'. If you decide that (b) is off topic, I'd say (a) is on-topic. If you decide (b) is off topic, then you should have at least one (a) that is canonical that you can point new questions to (since I suspect you'll get lots of them).
To be fair, I can see both sides of this argument, but I'd urge you to be 'inclusive' rather than deletionist while the site is growing.