Think about it for a moment. We face all sorts of difficulties when we have a conversation. Here are just a few:
- We tend to talk in short, obscure, fragmentary utterances and so listeners need to fill-in the missing information and interpret what we are saying. This means a listener must often wait a while for something to become clear or must interrupt to clarify a point.
- We cannot plan a conversation ahead of time as we never know what our conversational partners may say or ask. A conversation has a habit of going where it wants to go and not where any of the participants wish to take it.
- When speaking we need to consider our listeners and modify our use of language on the fly so it is appropriate to the context, our listners evel of understanding or in a way that does not offend them.
- We need to decide when it socially acceptable to interrupt the person speaking - to come in at just the right moment.
- We need to plan how we are going to respond, if at all, while at the same time listening and in a multi-party conversation decide who to address.
It shouldn't be easy should it? But like me, I suspect you have never given it a second thought.
If you are interested in a scientific answer then take a look at the paper Why is conversation so easy? by Simon Garrod and Martin Pickering. They say its because the interactive nature of dialogue supports the interactive alignment of linguistic representations but I will leave you to make sense of that :-)
But the simple answer is that evolution has "wired" our brains for dialogue rather than monologue.
If we are "designed" for conversation - not for monologue then why do we inflict lectures on each other?
Credit: Thanks to Stephen Mugford. for pointing me to this paper