Susan Sontag
[Writer, theorist, and critic, b. 1933, New York, d. 2004, New York.]
Contrary to what is suggested by the humanist claims made for photography, the camera’s ability to transform reality into something beautiful derives from its relative weakness as a means of conveying the truth. 
Wright Morris
[Writer and photographer, b. 1910, Central City, Nebraska, d. 1998, Mill Valley, California.]
However much [photographs] may lie, they do so with the raw materials of truth. Martha Rosler
[Artist, b. 1943, Brooklyn, New York, lives in New York.]
The question at hand is the danger posed to truth by computer-manipulated photographic imagery. How do we approach this question in a period in which the veracity of even the straight, unmanipulated photograph has been under attack for a couple of decades. George Orwell (Eric Arthur Blair)
[Writer, b. 1903, Motihari, Bengal, India, d. 1950, London.]
Processions, meetings, military parades, lectures, waxwork displays, film shows, telescreen programs all had to be organized; stands had to be erected, effigies built, slogans coined, songs written, rumours circulated, photographs faked. Errol Morris
[Documentary filmmaker, b. 1948, Hewlett, New York, lives in Cambridge, Massachusetts.]
If you want to trick someone with a photograph, there are lots of easy ways to do it. You don’t need Photoshop. You don’t need sophisticated digital photo-manipulation. You don’t need a computer. All you need to do is change the caption. W.H. Auden
[Poet and writer, b. 1907, York, North Yorkshire, England, d. 1973, Vienna, Austria.]
The steady eyes of the crow and the camera’s candid eyeSee as honestly as they know how, but they lie.
Pedro Meyer
[Photographer, b. 1935, Madrid, Spain, lives in Mexico City.]
Before, the myth of “photography doesn’t lie” was used in order to cover up tricks. If I [make a] portrait [of] you, accommodate you, illuminate you, put make up on you or use a filter, am I not manipulating reality? The only difference is that now I can do it from the computer in the postclick instead of the preclick. If I decide to photograph something instead of something else, I also manipulate reality. Of course a photograph can lie or commit abuse, but it always could. Auguste Rodin
[Artist, b. 1840, Paris, France, d. 1917, Paris.]
It is the artist who is truthful and photography which lies, for in reality time does not stop, and if the artist succeeds in producing the impression of a movement which takes several moments for accomplishment, his work is certainly much less conventional than the scientific image, where time is abruptly suspended.