In a Philosophical Discussion . . .

. . . three's a crowd and four's a cross-conversation. 

One-on-one, back-and-forth, defining and refining, pursuing the point, focusing like a laser, driven by eros for truth but free of polemos under the aegis of philia.  But also under the aegis of 

Amicus Plato, sed magis amica veritas.

And with no illusions about achieving agreement. An attainable goal here below is clarity about differences. "I will teach you differences." (Shakespeare, King Lear, Wittgenstein.)