A second precursor is a growing movement. The more popular a cause, the wider the range of personalities involved, the wider the range of tactics that will be employed.
"Years ago the Sierra Club was considered a very radical organization," says Rosebraugh of the ELF. "Today the Sierra Club is one of the mainstream organizations in the country. And I think one of the reasons that occurred is that there are more radical organizations out there such as the ELF that have been an arrowhead pushing that social movement."
This argument also attempts to justify the seeming futility of arson attacks. Sure, a torched house will be rebuilt. But the memorable force of the action will remain in public consciousness when mainstream organizations push for other environmental causes.
Naturally, the Sierra Club wishes the ELF would get off its side.
"I disagree [that radicals help the movement] in a lot of ways," says Sandy Bahr of the Sierra Club. "Maybe things would be different if things were reported differently, but we all end up being lumped together. Issues get lumped together and environmentalists get lumped together."
So which perception is correct? Perlstein says history shows a definitive answer.
"Historically, unfortunately, the radicals are correct," he says. "There has never been a major social change occur in the United States, and probably elsewhere, that hasn't had violence associated with it at the beginning."
To hear the ELF tell it, burning houses is not a violent or terrorist activity at all.
"We condemn all forms of terrorism," the ELF wrote in its claim of responsibility for the Long Island attack. "A common definition of terrorism is 'to reduce to a state of fear or terror.' We are costing them money. If change falls out of your pocket, you are not in a state of fear or terror. . . . We are non-violent."
The message goes on to say that targeted houses are searched for "all forms of life" and that citizens should donate generously to local volunteer firefighters. "Don't be mad at us," the message concluded, "be mad at urban sprawl."
In other words: Sure, we're burning down houses, but we're being awfully nice about it and have a darn good reason.
The argument places the definition of terrorism on the intent, not the effect. It's saying that because environmental arsonists have good intentions, nobody should be afraid. Those living near the Phoenix Mountains Preserve would likely disagree.
"This is a crime, and it's definitely a political issue, so it's definitely terrorism," says Perlstein. "By every definition of terrorism, it's terrorism."
Counters Rosebraugh: "A classic non-violent protest that is completely legal involving picketing in front of a retail store can easily instill fear in the store owner, the employees and the customers. But does that make it violence? No."
The "terrorism" label may be debatable, but there is no doubt environmental arsonists are seriously flirting with physical violence. After all, it's all fun and games until a firefighter hosing down a cooling house accidentally steps through a charred floorboard and falls into an undiscovered basement, a thousand-degree BBQ pit full of unseen collapsing walls and asphyxiating blackness -- "a widowmaker," as firefighters call it.
Even those who agree in theory with the ELF say hit-and-run arson involves too many unpredictable variables, too many things that could go wrong, and, by all logic, eventually will.
"I have never said [accidents] are not a possibility," says Rosebraugh. "But I do think that the people involved in the Earth Liberation Front take the utmost precautions to ensure that no one gets hurt, and their record so far has spoken for itself: There have been no injuries abroad or in Europe."
Perlstein says he fears that domestic protest groups will begin attacking human targets. In Europe, where animal activists use more extreme tactics than their North American counterparts, some activists have mailed razor blades and letter bombs to those who support vivisection.
There is also a political danger in the Left using more extremist techniques. Amster, despite his years of frustration fighting to preserve open space and admitted sympathy for environmental arsonists, points out that escalating tactics may up the ante for everybody at the ideological table.
"If you admit the possibility that you can use arson for your principles, then you have to admit the possibility that other people could use it for their principles," he says. "And what would other groups decide to burn down if they used that tactic? You might have the Fascist Right burning down art galleries or synagogues."