You might want to start with chosing who your going to use in the conversation or more to the point how they speak...ie colloquially or a constant barrage of sophisticated language.
After that think about how you speak in conversation. Its not a set debate so you dont have to wait for the other person to stop(are you meant to be supporting one opinion?)...so have the characters interrupt and speak over each other as they attempt to convince the other that they are wrong. Often its good to do point for point. ie have one say their point followed by evidence then the other interrupts with evidence as to why they think what they do.
And itll probably be a good idea to establish what they are important in regards to.......(what)......the way they r read or their overall message or effect or what they mean to the audience or what....
and for issues things like eugenics and genetic modification and consumer societies, the use of technology to control society, people playing god(absence of god/replaced by other things/obsolete), mankinds disregard for nature(playing god), all powerful nation-state (BNW its political and in BR its economic/consumer driven)
hope that helps sorry if it doesn't
