A while back my ESTP sister and INFJ mother were arguing vehemently over the definition of empathy.
I tend to have the view that there are several versions of empathy. I had an English teacher who was absolutely amazing at what he did. I learned so much in his class. It was because he was very empathetic in the sense that he was very good at seeing things from the perspective of his students. He was able to put himself in our shoes and see things from out viewpoint. So he was very able to meet us right where we needed to be met and explain things in a way we would understand. It was a sort of...um...mental empathy?...viewpoint empathy?
Then there's the emotional empathy I normally think of when I think of empathy. There's the kind where you feel for someone because you've experienced the same pain that they have. Then there's another kind that I believe exists where one doesn't necessarily have to have gone through what the other person is going through but can still sort of get really really in tune with what the other person is experiencing and feel for them.
And there's Marshall Rosenberg's NVC definition of empathy.
Anyway, to answer you questions:
What constitutes proof of having empathy? *shrug* I dunno. I suppose it depends on how you define it. What I go with is: If their mirror neurons work they have empathy.
Is it possible to project personal feelings onto others? Most definitely. Is that empathy? No. But I suppose that depends on the context you meant for that.
Is it possible to have selective empathy? I think so. I sort of feel like every healthy human being is empathetic in the sense that they are capable of empathetic experiences. But a lot of us are only really good at the kind of empathy where we feel for others who are going through things we've gone through. So then we have empathy for some people/pain but not for others and it's kind of "selective" in that sense. But maybe you meant can we choose to have empathy for some people/pain/situations/viewpoints/whatever and then choose to not for others. I dunno.
Is empathy an extension of one's ego or a perspective from a different vantage point than the self. I think it's both. "My ego is seeing and experiencing things from your persecutive which is causing me to experience the emotions you are" ???
And then well obviously if you're talking about the "mental empathy" I was talking about earlier then of course empathy is a perspective from a vantage point other than the self.
But maybe you meant "extension of one's ego" in a different way.
Anywho, where are all the INFJs and INFPs? Shouldn't they be here by now?
P.S. I might delete this post. Chances are someone is gonna come and post something that I'll feel is way better than this post and feel the need to delete this one.
ETA: As for the self identification as either having or not having empathy/ being or not being empathetic. Do you, Annwn, self identify as being empathetic? If you do, why?
And to those who self identify as not having empathy or not being empathetic...how are you defining empathy?