I once had an ENTP neighbor who I talked to a lot. We could talk for hours about nothing and sometimes, something, but never really arriving anywhere. He was a most excellent devils advocate. He was mid 50s, bachelors in math and chemistry, with a career background in real estate... Here is my take on his particular need to argue.
Something would interest him. Think of it as a point. Before he could accept it he would have to circle the point, in his mind. Gather information and test thoughts out. I imagine this to be traveling in a circle around the object of interest. As he was circling the object he'd go off on tangents, forming another circle. Think of a fractal. Eventually he'd arrive at a conclusion, close the tangent and continue his circling. He would become very obsessive about this object after time. Very consuming of his time/energy. Eventually he'd arrive at a conclusion about the object of interest. At this point he'd lose almost complete interest. Another shiny has drawn his attention. and besides he now "understands" the object.
It is during this test thoughts out and circling that he would solicit opinions and while doing so make you prove him wrong, which he didn't mind, he actually liked that (usually), since he could close a tangent/circle and continue searching for understanding of this object of interest. He'd argue, but not for arguments sake, but rather, to get to the bottom of the matter, when he was focused.
He is some sorta theist (non denominational) ftr, me, I'm an atheist and we'd "talk" for hours on the subject. Quite enjoyable. He is no longer my neighbor and I miss those long talks about the world we live in.
Vaya con dios Paul! hehe