Passage Summary: Even though extreme environmentalists are often wrong or unrealistic, they are useful because they scare people enough to overcome political laziness and get things moving.

Conclusion: Radical environmentalists play a beneficial role in society despite their often incorrect claims and impractical ideas.

Reasoning: Social and political progress on environmental issues is so difficult to achieve that it only happens when the public is motivated by a fear of disaster, which these extremists provide.

Analysis: To identify the conclusion here, look for the 'pivot' in the editorialist's tone. The passage starts with a concession—admitting the radicals are often wrong—but then uses the word 'But' to introduce the main point. The statement following 'But' is the central claim the author wants us to accept. The final clause, beginning with 'for,' provides the evidence explaining why that claim is true. Since the final sentence supports the second sentence, the second sentence is our main conclusion.