“There is always the possibility, if not the necessity, of doubting information one does not observe directly. If indices are signs that often come to their receivers at a spatial or temporal remove and, unlike icons and symbols, need contextual information to signify, how is it that they are able to inspire conviction on the part of their receivers? Moreover, if this is the case, why have theorists of photography associated them with certainty and proof? To answer this question, we will have to look a bit more closely at the means by which they signify.”

From Issue #122 (available here)