Agreed. But whose consistency is being used? It might be necessary for a series of small agreements. Sometimes conversation stops dead at the “mutual definition” stage. So what then? Take a step back. Find points in common. Other definitions. Leave the context of the argument in question. Have a beer together as it were. Tone conveys meaning as do words. Style conveys meaning as well as words. Sometimes the argument is less about the words than the environment created within the parameters of the conversation. There’s multiple paths to reach a consensus. Sometimes a total consensus isn’t possible. But I believe a partial consensus is possible. That keeps the doors open for future communication beyond the singular argument under discussion.