I say talk about economic policy. Argue for a position you believe in (be it Socialism, Laissez-Faire Capitalism, or whatever). I would start by using a anecdote that described the issue using the negative consequences of embracing the other perspective, immediately tarnishing the person's first impression of the opposite ideology. Then, I would involve logos by saying things like "just think about it, and you'll realize it makes perfect sense" and explaining my position as though it were a formula. Ethos would come into the picture when I mention the opinions of professionals and scholars who I've hand=picked to agree with me on the topic. Pathos has already been used in the form of the beginning anecdote, a "sob story" so to speak.
Hope that I helped!
