There are none. You cannot engage in any sort of reasonable debate with those whose final arguments devolve to the gun and the gulag. Socialism, despite its efforts to create the 'New Man', has ever and always relied upon coercion to maintain itself. Where experimental socialist/utopian communities such as Robert Owens' did not prevent their members from walking away, they all failed without exception - because people simply walked away when the problems arising out of the collision with socialist ideals and human nature became irreconcilable. As Muravchik said in the introduction to his book," If you build it, they will leave."
We're very close to fighting the next American Civil War over this and many other issues. Think long and carefully about your position once this starts. Fence sitters tend to catch fire from both sides.