Palin is controversial, in part, because America is divided over disability. We’ve established laws and institutions that protect people with disabilities. But we also do everything we can to make sure they don’t see the light of day.

Trig is a reminder of our fierce ambivalence over disability. Every mention of his name is a pinprick to our conscience. Every photo of mother and son is a reminder of concepts — vulnerability, dependency and suffering — our culture no longer tolerates, as well as virtues, such as humility, dignity and self-sacrifice, it no longer extols.

Trig is also a reminder of an inescapable truth: Disability is an inherent part of the human condition. At a time of deep cultural divisions, 1-year-old Trig Palin represents the deepest division of all, between a culture that increasingly sees genetic perfection as an entitlement and a culture still rooted in the belief that human beings are defined not by their capabilities but, instead, by the very fact of their humanity.