I believe the passage is:
As of 1973, that U.S. had a population of 210 million people, who were increasing by 0.8 percent per year. Outside our lifeboat, let us imagine another 210 million people (say the combined populations of Colombia, Ecuador, Venezuela, Morocco, Pakistan, Thailand and the Philippines) who are increasing at a rate of 3.3 percent per year. Put differently, the doubling time for this aggregate population is 21 years, compared to 87 years for the U.S.
-Garrett Hardin, "Lifeboat Ethics: The Case Against Helping the Poor"
The answer is;
It contains facts and figures that help to prove the author's point.