Whatever objections there may be to public aid, it has to be admitted that in some circumstances no housing improvement is possible without it. The difficulty is to obtain the improvement without doing more harm than good. When it is necessary to grant public aid, it should be given as a last resource after other means of supplying accommodation have failed, and it should be given in a form that will assist rather than impede private operations in house building. It may be accepted as an axiom that the best way to supply new houses for those who can pay for them is by private enterprise, subject to adequate government control. When public aid takes the form of financing the building of houses to rent at less than is required to meet the reasonable requirements of private investors, this eliminates private building of such houses. When rents of existing houses are artificially restricted, the effect is the same. When, however, public aid is given toward the purchase of land for parks and playgrounds, or to the construction of public utilities that cannot be made self-supporting, the result is to stimulate private effort in building.

To withhold public aid toward the building of new houses is not necessarily to leave the problem unsolved. It has to be recognized that old houses represent the largest proportion of dwellings in a city and that a very large number of the population must always live in old houses. It is not only impossible to build and rent new houses as a commercial proposition for the very poor, but also for a substantial proportion of those whose earnings are adequate to make them self-supporting. In other words, a large percentage of workingmen who are not in the poverty class are able to live only in old houses. In these circumstances, it may be asked, why must the solution of the housing of the very poor consist of building new houses, when so many who are comparatively well off must live in old houses? Why should charitable means be employed to subsidize new houses for those who can pay least, partly at the cost of those whose means are insufficient to enable them to live in new houses?

In cases where public bodies cannot provide new houses without giving charity, it follows that private enterprise cannot do so. It has to be recognized that new houses cannot be built to compete with old houses when there are sufficient of the latter to meet demands. So long as old houses are required to be healthful, there is no reason to disregard economic conditions by forcing the erection of new houses for those who can least afford them. There will always be large numbers who can afford only the cast-off houses of those slightly better off than themselves. So long as these cast-off houses are healthful and not overcrowded on the land, they may form wholesome accommodation. The public authorities are responsible for seeing that such houses are made and kept in good habitable condition, first, by requiring old houses to be kept in good repair, and, second, by purchasing land to open up congested areas.