Another form of the exchange equivalence theory would disregard the problem of _equality_ of gains, and assume that justice is realised whenever the contract is free from force or fraud. In such circumstances both parties gain something, and presumably are satisfied; otherwise, they would not enter the contract. Probably the majority of employers regard this rule as the only available measure of practicable justice. The majority of economists likewise subscribed to it during the first half of the nineteenth century. In the words of Henry Sidgwick, "the teaching of the political economists pointed to the conclusion that a free exchange, without fraud or coercion, is also a fair exchange."[215] Apparently the economists based this teaching on the assumption that competition was free and general among both labourers and employers. In other words, the rule as understood by them was probably identical with the rule of the market rate, which we shall examine presently. It is not at all likely that the economists here referred to would have given their moral approval to those "free" contracts in which the employer pays starvation wages because he takes advantage of the ignorance of the labourer, or because he exercises the power of monopoly. No matter by whom it is or has been held, the rule of free contract is unjust. In the first place, many labour contracts are not free in any genuine sense. When a labourer is compelled by dire necessity to accept a wage that is insufficient for a decent livelihood, his consent to the contract is free only in a limited and relative way. It is what the moralists call "_voluntarium imperfectum_." It is vitiated to a substantial extent by the element of fear, by the apprehension of a cruelly evil alternative. The labourer does not agree to this wage because he prefers it to any other, but merely because he prefers it to unemployment, hunger, and starvation. The agreement to which he submits in these circumstances is no more free than the contract by which the helpless wayfarer gives up his purse to escape the pistol of the robber. While the latter action is free in the sense that it is chosen in preference to a violent death, it does not mean that the wayfarer gives, or intends to give, the robber the right of ownership in the purse. Neither should the labourer who from fear of a worse evil enters a contract to work for starvation wages, be regarded as transferring to the employer the full moral right to the services which he agrees to render. Like the wayfarer, he merely submits to superior force. The fact that the force imposed upon him is economic instead of physical does not affect the morality of the transaction.