Originally Posted by MonoVCPHG
Consider it a tax break for those willing to contribute to the continuation of the human race.
Or it could be considered a tax break for those willing to contribute to overpopulation or the over-consumption of the earth's resources.
That line of reasoning is not a terribly valid one for justifying tax breaks considering the variety of ways people contribute to the betterment of the world with or without children.
(not saying there may not be other valid reasons, however, but it's pretty fair to call what seems to be a pretty unfair system into question)