When in doubt, read the manual!

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D&D Players Handbook v3.0

Evil rangers, though rare are much to be feared. They revel in nature's thoughtless cruelty and seek to emulate her most fearsome preditors.

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DnDResources.com

A Ranger serves a cause. He has an ideal that sustains him through the cold, bleak, hungry days alone on the border, watching over simple folk who likely do not appreciate or even know of his efforts.

The cause may be the defense of a realm, the protection of innocent creatures, of the unspoiled land, or of a specific tribe. This in no way implies a specific alignment. An Evil Ranger may watch the boundary's of Mordor out of devotion to the Dark Lord. An Orc Ranger may scout ahead of the raiding party, committed to reducing casualties among his brethren by eliminating Elven snipers.

So Stone is right. An evil ranger is more of a supporter of evil rather than an anti-ranger.