A dispute over territory in the backseat of a car qualifies as an argument, for example, in the unlikely event that one child attempts to persuade his audience rather than slug it.

In My house I would also teach that the difference between 'argument' and 'fight' is quite distinct from the difference between 'good' and 'bad'. I'd also teach them that a good response to a persuasive and audience swaying argument that they should give territory to another is "No. I want it."