An image of suffering does not carry a fixed meaning; its significance depends on the caption, context, and political sympathies the viewer brings to it. The same photograph of dead bodies can be enlisted to prove opposing claims, which is why wars are fought partly over how images get labeled.
The assumption that constant exposure to atrocity photographs inevitably numbs viewers into passivity is overstated; shock can renew itself, and whether an image anesthetizes or galvanizes depends on the viewer's situation, not on repetition alone. Habituation is one possible response, not an automatic law of perception.
Feeling compassion while viewing distant suffering can function as a substitute for action rather than a spur to it, letting the spectator feel morally engaged while remaining a bystander. The sentiment can mask the viewer's own connection to the privileges or systems that produced the suffering.
Even documentary war photographs can be composed as beautiful, and that formal beauty risks converting horror into something to be contemplated as art, diluting its claim on conscience. The more skillfully an atrocity is rendered, the more its subject may be eclipsed by admiration for the image.
In Three Guineas (1938) Woolf examined Spanish Civil War photographs of mangled corpses and houses, assuming any decent person would read them as self-evident proof of war's horror and share her antiwar revulsion. Sontag uses this to argue that 'we' is presumptuous: a militarist or partisan could look at the identical pictures and see justification or the enemy's crimes instead.