I'm often presented with a "the cycling of the generations is crucial. Without it progress would slow, the environment would be over-stressed, and there would be far fewer jobs for new young people" argument. I reply with question 8.

1. All of these are simply increased intensity of problems that already exist. We could solve all these problems right now by killing the elderly. Are you willing to commit suicide when you reach the age of 60 (or 50, or take-your-pick) to help solve these problems? Or are you willing to grant that death is a very (ethically) bad solution, and much better solutions could be found if death was taken off the table?