Posner overcame these problems by obtaining from industry studies estimates of demand at the relevant points along the demand curve. However, it must be recognised that the validity of these results depends crucially on the validity of his initial assumptions. Posner's results may be questioned on a number of counts. There are many reasons to suggest that the value of rent seeking expenditures will not equal the total value of rents. Secondly, the contenders may not compete from an equal footing.
Some interests are better organised than others, ie.
In general, assuming a limited number of players, and knowledge as to the probaility of success the total value of rent seeking expenditures will be equal or less than the total value of rents. However, with larger numbers of players and uncertainty regarding probabilities of success, firms will not be able to make rational decisions based on perfect information. In this case expenditures could be less than , equal to or exceed the total value of rents. When one considers that many other firms may also engage in rent avoidance then this argument is plausible. Indeed, Posner argues that due to rent avoidance the social cost of monopoly may be high even for a monopolist earning only a normal return.