Q&A 1, Second Answer

My question is: Since Donovan’s argument rests on the assumption that all humans have and use the capacity to experience sympathy for non-humans, what would she say about humans who lack that capacity (through a mental dysfunction or a simple difference in personality?)

I think she would say that those people are dysfunctional, and that their judgement is therefore invalid.  This would be consistent with her belief that only one view is possible for those who truly experience sympathy.  It also shows what is, perhaps, the greatest problem with her argument - despite her statement that everyone's emotions regarding animals are valid, she goes on to say that if one's emotional response to animals does not match with hers, one is not trying hard enough, or has not encountered the right circumstances.