Some people say life 3 to heal others, some say life 4. While I have done life 3 in some campaigns I think I'm going to make it my general rule that you need life 4. Partly this is because I think the 3rd edition main book says so. Partly this is because people play much more realistically when they know that if they got shot in the face it's a lot less likely that Zora the wonder-witch starting player will shower her pixie dust and wipe that wound away. It's possible there might be some exceptions, but you'll have to discuss it with me and I'll most likely say no. But if you present a nifty argument like you want to be able to heal with life 3 in a specially designed chantry or you have Burning Aura or something like that then give it a try. Also keep in mind that your mage isn't going to think, "hot damn, I only have life 3!" (unless they're hermetic...stupid hermetics). I'm all in favor of mages trying to do things they don't actually have the dots for. Who knows, maybe they'll get really really lucky.