Argument based on speculation

I was wondering if it is acceptable to argue a point that cannot be proven. For example; Person A states that majority of people on this earth have never stolen anything in their life. Would it be acceptable to argue against Person A using speculation as to why the majority of people have stolen at least once(human nature, etc)?

>>9
>whether it's candy from a friend, a cigarette, a little bit of money, whatever

What about little blue pens from argos? Everyone steals those.