Richard A. Epstein writes: "The libertarian prohibition against force does not take into account the possibility that successful cooperation in key situations can be thwarted by individual holdouts. It will not be possible to build a railroad from point A to point B solely by getting the cooperation of 99 out of 100 private landowners along the way. The last one (indeed all) must be brought into line, and the way to do it is to compel the purchase by paying them the highest value of the land in any alternative use whose value is not dependent on the railroad that is about to be built. The public, including those whose property is condemned, gain the benefit of the railroad, but if compensation is correctly calculated -- a big if -- no individual suffers financial deprivation in the process. State coercion is used to create the win/win situations found in private contracts. Randy Barnett responds: "Due to limitations on our knowledge, we have little choice but to rely on the principle of freedom of contract to answer these questions, however imperfectly. Unlike self-defense and restitution, exceptions for free riders and holdouts cannot be justified as the enforcement of the rights of others. David Friedman adds: "To justify taxation we need the additional assumption that rights enforcement cannot be done by the state at a profit, despite historical examples of societies where the right to enforce the law and collect the resulting fines was a marketable asset, and that the government cannot charge enough for the use of its roads to compensate the owners whose land was condemned."
Thanks to David Sucher