I don't really think the traditional alignment system works for any of the classes. The classes are mainly power that can be either used for virtuous purposes or abused. White magic and Black magic are a perfect example. White magic is the power of creation vs Black as the power of Destruction. However White magic is powered by drawing strength from the world around it and if abused can damage the natural world it draws power from. Likewise BLM magic can be abused but likewise can be used to destroy dangerous threats.

Its the use of the power rather than the power itself that is good or evil. The power just is.