In Modern Magick Donald Michael Kraig defines black magic the way most people would expect...that is, magic used to do harm. However, he defines magic used for practical ends to do good as grey magic, and goes on to emphasize that in seeking to do one person good you may accidentally do another harm. White magic, he says, is only magic used to connect you with the divine...in Western occultism, that means your Holy Guardian Angel.
I have...issues...with this, aside from the subtle racism of "white = Good/black = Evil." I believe he got these definitions straight from his Golden Dawn sources, and I think they are wrong too. Heh. But the problem here is fundamentally a difference of world-view. If you believe that spirit and matter are two completely different things, and that "goodness" resides primarily in the non-material, then of course you think that the purpose of all "spiritual" activity is to connect with that non-material source of goodness, which is above all petty matters of the flesh or paying rent; and further, that any application of spiritual power to mundane or material matters is missing the point at best and at worst a serious misuse of such power.
I don't agree with any of that. It doesn't help that he seems to muddle "benefit" with "good." I don't have a problem with using magic for either doing good or my personal benefit, but I don't confuse the two. Later in the book he says that for the advanced magician there isn't really any white, black, or grey magic...by which he seems to mean that if you're enlightened enough you won't want to do bad things with magic. I think that's both kind of true and really stupid. That is, I do think that if you are well-integrated enough and connected with your Godself (in Faery parlance) or Holy Guardian Angel, you are considerably less likely to want to do stupid things that will bite you on the ass, or which are malicious or short-sighted, because of the added perspective. However...There are a lot more people in the world who think they are enlightened than who actually are. We've all met people who are completely convinced that they are too "advanced" to feel anger or other base motives, when it's obvious to everyone around them that they are fooling themselves. As neighbors and acquaintances those people are annoying; as workers of magic they are dangerous. And where it starts is being ashamed about wanting what you want and seeing that as "bad," which just encourages you to conflate what you want with what is "good." Good for me isn't always good for you, or for everyone. Sometimes I may choose one over the other, but I try not to ever confuse them.
I especially do not confuse what I want with what deity wants; that's how you wind up with Christians making imprecatory prayers to harm innocent people with a clear conscience. Or Pagans claiming that thus-and-such deity told them to do something which just happens to benefit them personally. I note in passing that one word for this is hubris, and it's the kind of behavior that in Greek myths tends to get people into highly imaginative trouble.
It's not that I don't think there's any serious difference between beneficial and malefic magic, that the latter doesn't have consequences, or that it's not worth trying to suss out the difference; I do. I just don't think that making sharp distinctions between "material" and "spiritual" is a useful way to accomplish any of that. For one thing, I think those distinctions are false; I'm basically an animist, and not much of a Platonic dualist. For another, you can absolutely do bad things for ostensibly spiritual reasons (see examples in preceding paragraph, also most of history). I tend to judge good and evil by consequences, while acknowledging that can be difficult to do. "Even the very wise cannot see all ends." When judging the good or evil of one's own actions, a bit of humility can be strangely useful, while grandiosity is not.
I have never thought that putting magic in a separate moral category, with special rules, made any sense. If it's wrong (or right) to punch someone in the nose, then hexing them is pretty much the same. That of course leads me to the conclusion that categorizing different types of magic in this way isn't especially helpful. But if black and white don't mean evil and good, what do they mean?