“At every moment, anyone who dares to predict the future depends largely on the projection of present trends: but as the microbiologist Rene Dubos has said, "Trend is not destiny." Malthus wisely never put much rhetorical force into his predictions of future population size. He deserves neither positive nor negative credit in this area.

A word about prediction. Embarrassing experiences, coupled with Dubos's warning, have led demographers to state repeatedly that they do not make predictions: only projections — projections of present trends. Trends may change with little warning. After two repetitions in the daily press, what begins as a projection metamorphoses into a prediction in the minds of readers. In spite of their warnings, demographers are repeatedly castigated for making predictions that don't come true.”