Questions about knowledge are not, historically, photography’s first line of defense. The earliest controversies center on the question of whether photography’s fidelity to appearances and dependence on a machine did not prevent it from being a fine art—as distinct from a merely practical art, an arm of science, and a trade. (That photographs give useful and often startling kinds of information was obvious from the beginning. Photographers only started worrying about what they knew, and what kind of knowledge in a deeper sense a photograph supplies, after photography was accepted as an art.) For about a century the defense of photography was identical with the struggle to establish it as a fine art. Against the charge that photography was a soulless, mechanical copying of reality, photographers asserted that it was a vanguard revolt against ordinary standards of seeing, no less worthy an art than painting.

Now photographers are choosier about the claims they make. Since photography has become so entirely respectable as a branch of the fine arts, they no longer seek the shelter that the notion of art has intermittently given the photographic enterprise.