1. If we wanted to try to reconstruct a "discourse on method" appropriate to the genre of prison drawings, we might start with the reasonable assumption that we would be dealing principally with erotic pictures drawn from memory. Prisoners tend to read a lot of Foucault, so they might describe their drawings as having a double preoccupation: firstly, the erotic; secondarily, memory.
2. Patently historical causality cannot work backwards, otherwise we could clearly connect Schiele's abstract style, developed around 1910, with his military service as a prison guard, during the First World War. If we want to establish a connection between Schiele's pictures and prison art, we can only make suppositions about some sort of connection, in the artist's undocumented personal history, unless we are to suppose that society in all its breadth was thought to constitute a vast prison camp.
3. Because the inevitable deficiencies of technique and memory necessarily have to be propped up by the efforts of the self in its naivety, the naivety that is hated and persecuted, by the blankly staring social superego, prison art becomes the art of exploding the anathematisation of naive individualism, not really democratically, but rather through the conjuration of the incontrovertible.