However I didn't just assume a lack of free will. I also assumed a lack of identity. Do you realize that who you are is socially defined? When you breathe in, the air in the room around you becomes part of you. When you breathe out, you lose certain gases. When you eat your food, similar story. There's a good case to be made that "you" are in the entire room or the entire food chain. That does make causality and culpability hard to assess objectively. When we do so, we do so subjectively.
In that case I dub you a mushroom.
We would do well to remember that every now and then. People who get too into pretending their perspective is objective reality tend to do stupid things.
> like a virus doesn't become part of me -- the immune system acts a biological discriminator between what is part of me, and what is not
But what about symbiotic organisms? What about your microbiome? Or the mitochondria, which began its existence as a separate organism? Or, they say our DNA includes many viruses that our ancestors contracted. A number of these things do stick with us and we sometimes even become totally dependent on them to function.
To pick one possible simple and broad definition from WP, "Identity is the set of qualities, beliefs, personality traits, appearance, or expressions that characterize a person or a group." -- you made it sound like that set is empty, which doesn't make sense to me. My identity is part of "I". Every being has an identity; it's not something you can get rid of?