All Is Force -- The World View of the Left

The Left cannot tell the difference between voluntary exchange and the use of force. That is why they think there is no difference between slavery and working for an employer for pay. That is why they think it is valid to replace voluntary exchange with force. If it is all force anyway, it might as well be MY force. How does one combat this? If they cannot see the difference between a voluntary economic exchange and the use of force to accomplish your ends, how can you begin to have a discussion?