His major contribution to this problem is probably the argument (1964) for tradable birth-right permits. His dissidence on this issue is "political" – it runs against the grain of the political climate both then and now. If he was correct about the emerging seriousness of the population problem and if that level of concern is one day reflected in popular political sentiment, there is every reason to expect the profession to embrace Boulding's call for tradable birth-right permits, since it is based squarely on neoclassical concern for efficiency.