The cosmopolitan approach is required for some worldwide problems, such as ozone depletion, acid rain, and the exhaustion of oceanic fisheries. By contrast, potholes and population call for a parochial orientation. But if local "laissez-faire" in population matters is interpreted to mean no borders, a suicidal commons results. To survive, rich nations must refuse immigration to people who are poor because their governments are unable or unwilling to stop population growth. With its borders secured, how is a nation to control its own population growth? In one sense population control is inevitable; in another problematical. If the citizens of a nation pay absolutely no attention to their numbers, population will eventually be controlled by "nature"—by disease, starvation, and the social disorders that follow from too many people fighting for limited resources. But when wellwishers call for "population control" they mean something gentler than nature's ultimate response. Can we now predict what form successful human measures will take? I don't think we can, because the question demands that we successfully predict human history. Who, in the year 1700, could have predicted the Constitution of the United States? Who, in 1900, could have predicted Chernobyl? What happens in history is the result of the interaction of (first) the dependable "Laws of Nature" with (second) the apparent capriciousness of human nature. As concerns the first component, Francis Bacon should be our guide: "Nature to be commanded must be obeyed." Coming to the second factor we turn to the inventor of the holograph, the Nobelist Dennis Gabor: "The future cannot be predicted, but futures can be invented." Ignorance of this insight leads the public to take too seriously the projections of demographers (who rightly insist that they cannot predict the future). Demographers merely project curves—present trends—into the unknown future, all the while knowing—as Rene Dubos said-—that trend is not destiny. This book has been one long dissertation on the laws of nature that must be obeyed, namely: the properties of exponential growth; limits generally; the properties of usury; the significance of human unreliability; and the consequences of reproductive competition (including natural selection). But within these limitations lie many possibilities of population control. Some controls are kinder than others.