In the preceding paragraph we have assumed that the extortionate prices are operative at the same time as the excessively low prices, but in a different place. Suppose that the former are imposed only after the independent concerns are eliminated. The injustice to the competitors remains the same as in the preceding case. Although the extortionate prices are later in time, they are the instrumental cause of the destructive low prices through which the competitors were driven out of business. If the owners of the monopoly were not certain of their ability to establish the subsequent extortionate prices, they would not have put into effect the unprofitably low prices. Hence there is a true causal connection between the former and the latter. Although the connection is mainly psychical, through the consciousness of the monopoly owners, it is none the less real and effective. Its practical effectiveness is seen in the fact that the subsequent possibility of imposing extortionate prices will induce men to lend the monopoly money to carry on the process of exterminating competition. The process is maintained by means of the extortionate prices quite as effectively as though the two things were simultaneous. In so far as the patrons of the independent concerns are deceived into expecting that the very low prices will be permanent, and in so far as this impression causes them to withdraw their patronage from the independents, the latter are injured through another illicit means, namely, deception. The competitors have a right not to be deprived of their customers through imposture. What is the measure of extortionate prices in this connection? How can we know that the high, competition-eliminating prices are really extortionate? There are only two possible tests of just price. The first is the proper cost of production,--fair wages to labour, fair prices for materials, and fair interest on capital. If the monopoly does not raise prices above this level, it obviously does not impose extortionate prices, nor inflict injustice upon the eliminated competitor. Moreover, if the monopoly has introduced economies of production it may, as we have seen, justly charge prices somewhat above the cost-of-production level. But it may not raise them above the level that would have prevailed under competition. This is the second test of just price. No possible justification can be found, except one to be mentioned presently, for charging the consumers higher prices than they could have obtained under competitive conditions. At such prices the monopoly will be able to secure the prevailing rate of interest on its capital, and all the surplus gains that proceed from superior efficiency. A higher scale of prices will be, therefore, extortionate, and the competitors who are eliminated through its instrumentality will be the victims of injustice.[179]