I’d look at material reasons as the reason some have an inability to feel solidarity for others. Individualism, competition culture, pathriarcy, racism, imperialism etc. are the ideological structures that uphold capitalism. There are countless ways the superstructure pits people against each other and alienates them from each other. There have been studies on how difficult it is to organize a workplace in the US for example and the reason is speculated to be individualism and competition culture. Not some inherent trait in people who live in the US.

What is an isn’t a pathology should imo be defined as something that would exist in a person regardless of society, the conditions we all live in. A lot of things now framed as “mental deficiency” would probably not exist, at least not as they currently do. Empathy would probably look pretty different. The difference in how different cultures view psychosis is an example of this, in Western culture a mind like this is framed as deficient.

I would also be careful with a word like deficiency in the first place, because it frames a difference as something broken, wrong or abnormal. Framing some as deficient in any way is a logic of capitalism, it translates to an inability to be exploited by the capitalist and therefore as expendable.

Even bad is a loaded word and inevitably moralist so this is a difficult discussion to have. I’d just think about how a lot of the norms and understandings of good or “normal” we have exist purely to uphold capitalism and liberalism. Psychiatry and as a result psychology were historically used to control the deviant Others. They still often are.

This is why I’d be cautious of pathologizing “bad” or “lack of empathy” because this easily turns against for example autistic comrades who show empathy in a different way. Or against minorities who refuse to show normative liberal performative empathy when a ghoul dies.

To summarize my incoherent thoughts, I don’t think we should attempt to explain bad behaviour with the same tools that the ruling class uses to do that, aka by pathologizing them. Because that would be like claiming that some just don’t have empathy as a trait instead of understanding that we live in a society of deep alienation and individualism.