The question of an adequate supply of new houses is at present a vexed one and is likely to remain so for some years. Therefore it makes a good illustration of the difficulties involved in the question under discussion. Suppose it were possible for all the labor employed in the construction of houses to increase their effort and accomplish, let us say, a third again as much as at present. Would that increase of effort repay these workmen--would they receive higher wages? It is not a matter that can be argued with certainty. The expense of construction would fall rapidly, unless combination among the firms supplying building materials or among building contractors prevented such a fall. In the event that the cost of construction fell, there can be little doubt that more construction would be undertaken. Would the increased demand for construction lead immediately to an increase in demand for building labor sufficiently great to give employment to workmen who would not be needed on the old construction because of the increase in individual output? Would it be so great as to mean a more than proportionate increase in demand for building labor and a consequent rise in wages? Would its effect be felt immediately or only after the passage of some months, during which a number of the building laborers would be without employment? What will be the effect on employment two years hence? Looked at in this light, the skepticism of trade union groups in regard to appeals for an increase of effort is easy to understand. It arises from the simple desire of the group to protect their position in industry by the only means they possess. It is an attitude strengthened in many cases by the memory of weeks without work and efforts ignored. It is a bitterness, like to others, which men inherit from experience. Yet it can be stated with emphasis, that from the point of view of the wage earners as a whole, and of all of society, that any consistent adherence to this group demand theory of wages would be mistaken and unsound. The use of improved methods of production by any group, the more efficient performance of their work, may not result in a quick fall in the price of the product they are engaged upon, though sooner or later it usually does. The fall in price may or may not lead to rapid increase in the demand for the product of the group sufficiently great to give employment to all its members, or increased employment; although that result has usually appeared in the long run also.