During the past several months, I've had ample opportunity to think about the way a narcissist lacks empathy, contrasted by how an autistic lacks empathy. The two are distinctly different, but it's challenging to define the difference in terms of "empathy", "sympathy", and "compassion". The words seem somehow inappropriate and unfit for the task. Rudy Simone, author of Aspergirls, straight out says she's looked into these words, and can't come up with a meaningful difference.
But there is a difference in how a narcissist lacks empathy, and how an autistic does. A narcissist may very well be aware of how another person feels, but doesn't care. The knowledge might move them to exploit it for their benefit, but knowing about another person's pain doesn't move them to alleviate it. They don't feel compassion. A sadistic person, more so, is very much able to perceive another person's pain - and finds this an enjoyable experience.
On the other hand, an autistic person does care, as long as another person's feelings are somehow brought to their awareness. They do feel compassion, and are moved to alleviate the other person's pain. However, they tend to have trouble detecting and interpreting another person's feelings in the first place. (And if they do, they might find it overwhelming.)
I think this difference is important, and it should be possible to capture it concisely in the words we use. We ought to have a word which describes only being able to perceive how a person feels, and then a separate word to describe feeling with a person: i.e., being compelled to alleviate another person's pain, once you know about it; or being happy knowing that another person is happy.
We do have words for this latter concept - they are compassion and compersion, respectively. But we don't have a word that captures only the ability to perceive how another person feels, without implying how the perceiver feels about it. The words "empathy" and "sympathy" both go beyond the act of perceiving, and encompass "feeling with". This makes these words clumsy and inappropriate, because they neither accurately describe the narcissist (who perceives, but does not feel with), nor the sadist (who perceives, but feels the opposite), nor the autistic (who feels with another person, but has difficulty perceiving).
This difference is important, and ought to be understood. It is unfortunate that we lack good words for it.
As I finish this post, a realization flashes across my mind: that my mom lacks empathy in an autistic way, rather than a narcissistic way; and that I too have inherited some of this trait. This motivates me to write my next post.