Photography's assumptive nature
Photography advertises information as automatically true. It is a powerful medium for an argument, because the argument is only in the photography's implications, which, when interpreted through a person's eyes, feel just like reality in some senses. The danger of photography is that ironically, a photograph can be manufactured to suggest any argument. But still, the automatic assumption of the viewer tends to be that the photograph is automatically true.
The irony of art
In many ways, the artistic endeavor has hurt photography, feels Sontag, in the same way she feels that Whitman's naturalistic, blissful poetry of American landscapes was misleading. The land is beautiful, yes, but it is filled with people who are not blissful or ethereal. She feels that photography can be misused in the same way. Ironically, she picks Warhol as her target, a major hero in many artistic camps.
The irony of propaganda
The government would never lie to the masses by intentionally using photography as propaganda, right? Sontag suggests that ironically, the American life is so thoroughly influenced and inundated by propaganda that the average person doesn't even really notice anymore. The power of photography has weakened somewhat over time, as the public learned to be cautious, but Sontag played a real part in that, using this book to explain the painful reality of how the government has historically used photography as propaganda.
The irony of beauty and truth
Beauty is shown as a kind of derivation of truth in Sontag's arguments. A photo can be truly breath-taking and beautiful, without being honest. So, it is especially dangerous to misuse photography well, because by making something visually beautiful, a person might be inclined to ignore any logical error in the portrait. The crop yield photography in the late 1910's is her example. The pictures were encouraging, so people enjoyed them, but the truth was that the farmers had a low yield, so the food market would quickly become inflated.
Psychology and photography
The central irony of this book is probably this one: it seems ironic that we should live in a world where we have to be so skeptical of everything, but because of the progress of human technology, there is simply no knowing for sure if anything is trustworthy. The result is a kind of cynicism, but Sontag says that the cynicism is only a hope for something true. When a photograph says the painful truth that people want to ignore, she feels the power of photography has been used for its best purposes.
