Editorialist: The positions advanced by radical environmentalists often contain hypotheses that are false and proposals that are economically infeasible.
Conclusion (But)
Extremists have a positive role to play on environmental issues.
Evidence (For)
The social and political inertia around environmental issues is so stubborn that even small progress happens only when the public fears environmental disaster, whatever the reasons for the fear.
Evaluate
Whenever we read Main Conclusion / Role, we know to look out for upside down args (80% of the time the conclusion appears earlier than the evidence). Specifically, we know that - 65% of them are Pivot / Rebuttal conclusions - 25% of them are First Sentence conclusions
The first sentence definitely sounds enough like an author opinion, that we might have suspected it would be the conclusion. But instead of supporting that first idea, the argument then pivots away from it as the 2nd sentence begins.
When we see the PIVOT, we'd start thinking, "oh, this is probably the conclusion", and then when we see the Support Indicator "for" (FABS = for, after all, because, since), we know it's the conclusion because it's being supported.
Goal
Look for a restatement of the idea that extremists (i.e. radical environmentalists) can play a positive role when it comes to environmental stuff.