I agree with British economist Alfred Marshall about the high costs of "wasteful negligence" of the poor and with the Economist that the slums in our cities constitute "America's main domestic challenge." But those judgments alone would not justify making the urban problem the subject of the final substantive chapter of this book. What argues for coming to rest here on the contemporary urban problem is the view that it will be impossible, over a period of time, for the United States to play the role of critical margin on the world scene if we do not solve the urban problem. By "solve," I do not mean a reduction of the social pathology within the inner cities to the level of the more affluent counties that surround them. That will take time, perhaps a generation or more. Indeed, it might never happen. In any case, there is no quick fix. By "solve," I mean the bringing about of a systematic and substantive process of decline in the social pathology of the inner city. That demonstration will convince those who live there and the community as a whole that the job is doable. Right now, the greatest obstacle to a solution of the problem is the belief both in the inner city and the community at large that the job is not doable. As I said on another occasion:… When i am asked how I would rate the urban problem on the agenda of national-security problems, I reply it is our number one nationalsecurity problem. If we succeed in mastering the current urban problem of our country, we shall strengthen our hand on the world scene. We shall demonstrate that we can he a truly multiracial society, which is at the same time true to the international ideals to which we as a nation have long been committed. Nothing constructive can be accomplished in this dynamic, contentious, aspiring world without the active participation of the United States. But, ii we fail to master the urban problem, we shall, I fear, turn inward, away from the world. We shall he unable to play our part at the critical margin. And we shall risk a world environment of chaos.