shazam:
I was debating a "refomist Libertarian" about whether roads should be privatized, and he asserted that if roads were privatized, local road monopolies would grow. He also said that these monopolies would practice de facto eminent domain by blockading anyone who doesn't sell their property to the road owner by buying the surrounding property and refusing to let them leave. How could one rebut this argument?
Two thoughts on this one.
First, this is exactly what the govenment does when it wants to build a road. It first tries to buy the land and if that does not work eventually confiscates it. So the state wanting to build a road turns out to be a monopoly - bad bad bad if it is private, good, good, good if it is public? - . The idea, that a monopoly is always a threat is not correct. Monopolies are a threat if they are coercive monopolies only, that is if they can employ coercion to ensure no one else can enter their market segement. This usually can only be achieved through priviliges granted to such a monopoly by the state. Which in turn is not free market, but mercantilism.
Second, If someone has a property already than buying the surrounding property to block the way is not a valid option. Because the use of the property depends on getting to and from it, is part of the property itself. So, if the original property owners had a right to use the access to their property, which is usually the case :-), the denial of using that way by a new land owner would harm the original property and as thus is an aggression which is not acceptable under free market rules.
The only way to get out of the dilemma is either to come to favourable terms with the old property owners, or don't build the road.
In real life this, however, is a no brainer. Private roads are build to make profits. Profits are gained by customers that voluntarily decide to use that road. In a free market they would be free to do so or try to build another road they prefer to use. Hence, the monopoly faces competition and will employ every means it has on a free market( that means no priviliges whatsoever to coerce), to not outrage their customers, but to make sure they make as much profit as possible, which is only possible if customers love them roads enough to spend the tolls asked for.
The only road builder I am aware of that has no incentive to act like this, is the state. He has a coercive monopoly and no need to make profits from building whatsoever. His gains are reelection and increase of coercive power.