Passage Summary: Environmental issues happen because people want more than the Earth can provide, so the only solution is for people to want less.

Conclusion: The only way to solve global ecological problems is to decrease the level of human demand.

Reasoning: Ecological problems stem from an imbalance between the Earth's limited supply and humans' unlimited demand.

Analysis: The author identifies a gap between supply and demand and concludes that we must fix it by changing the 'demand' side of the equation. This ignores the 'supply' side; if we could somehow increase the sustainable supply through technology or better management, we might solve the problem without reducing demand. For the conclusion to be necessary, the author must assume that reducing demand is the only viable path. Look for an assumption that rules out the possibility of solving the imbalance solely by increasing or better managing the supply.