“…We note the theoretical difficulty which arises for the voluntary exchange theory in the event that some of the members of the community should attempt to benefit from public services without in turn being eager to contribute their share. While recognized as constituting a 'pathological group' (De Marco, [1934], p. 114) and a 'problem' (Benham [1934], p. 454), they are ruled out by the assumption of purely voluntary action. Assuming, however, for the sake of argument that all people act in the prescribed 'pathological' manner, the following problem arises: if the total cost of public services is covered by a large number of contributors, a reduction in the contribution of any one contributor will fail to affect notably the total supply of public services -either from the point of view of this contributor or in the eyes of other contributors who join in the consumption of the same indivisible services.…”