The thing is that empirical inquiry already suggests that mental illness is a much less important factor than personal associations. Considering that psychiatry has a severe etiological problem already, I don't think it's such a productive line of inquiry.
I mean, a pacifist could argue that choosing to join the military or obey orders that might result int eh deaths of civilians is pathological, or that states themselves suffer a sort of institutional pathology. But if one accepts a casus belli as a valid premise for military action, such questions are immediately collapsible into a cost-benefit analysis - which is, to some extent, how military forces actually operate.
I mean, a pacifist could argue that choosing to join the military or obey orders that might result int eh deaths of civilians is pathological, or that states themselves suffer a sort of institutional pathology. But if one accepts a casus belli as a valid premise for military action, such questions are immediately collapsible into a cost-benefit analysis - which is, to some extent, how military forces actually operate.
https://psycnet.apa.org/fulltext/2014-33751-001.html