The point is that you and I should not support the use of force to compel people to have just one government in an area.
I didn't get the emboldened part. Please explain
Ethics, i.e. moral philosophy, is a rather big subject; there are many concepts within it, but if you don't understand it naturally, you'd probably respond better to an argument of practicality,
as ErisDiscordia pointed out.
That part about not supporting the use of force I understood pretty well (and likely would agree to it). I didn't get what had been meant by (not) compelling people to have just one government in an area. They usually already have just one government in the area, why then should we compel them to in the first place? What did I get wrong here?