“Tell me about other strongly-held positions you’ve changed as the result of a discussion like this one...” is a direct way to start a conversation about the argument you’re proposing to have. “What sort of information would make it likely you could see this in a different way?”

I found Fisher’s approach totally uncynical. His mission statement is simple and, in its simplicity, quite radical: We should enter conversations not to prove but to learn something. Through conversations we are supposed to be changed and opened up to one another, for the puddle between us to shrink.