Much of the writing that's been helpful to me as a photographer hasn't been about photography at all. Frank and I have both stated in another thread (a couple months ago) that we thought "On Photography" was a terrible book.
A couple posts above someone asked for a bibliography of suggested books and that's a great constructive direction for a thread like this to head in so I'll put in my two cents about the writing I do think is good:
The best writing I've ever read on photography is James Agee's introduction to Helen Levitt's "A Way of Seeing". Helen didn't choose him by accident. Also great is Jack Kerouac's introduction to Robert Frank's "The Americans". Once again, that pairing was no accident. Basil Davidson wrote very well for Paul Strand's "Tir A Mhurain" but that writing is more about the subject than about photography. Meyer Schapiro rarely wrote about photographers but his essay in Robert Bergman's "A Kind of Rapture" is worth reading, I think. Otherwise, Meyer Schapiro on anyone is worth reading. E.H. Gombrich's "The Story of Art" is wonderful. Back to Agee, his writing on the same subject as Walker Evans' pictures in "Let Us Now Praise Famous Men" is beautiful and rings true to me. Walker Evans own writing on his own work is great reading. Ben Lifson (
http://www.benlifson.com) is worth reading on anyone, especially on Atget, Kertesz and Winogrand. He's getting even better with age of course and his new book on the history of photgraphy (understood as a visual art) is going to be a fascinating read, based on the drafts I've seen so far. People can read his column for free right now on-line and that writing is, in my mind, truly helpful to serious photographers. All of these people write, first and foremost about "the thing itself" (to borrow and re-apply from Szarkowski): about art, artists and subject. The writing is not a means of advancing an agenda, per se.
In terms of true philosophy with respect to visual art, I don't know of anything better than Suzanne Langer's "Feeling and Form". In my mind, it's everything Sontag's writing isn't. Her writing, sometimes very dense, is truly rigorous and fair and honest. There's no smoke and mirrors such as we sometimes see when an author uses a nominal subject as a "Trojan Horse" for an entirely different kind of agenda. ie: Contrary to Sontag's assertions, the camera is certainly not a phallus, by any stretch of the imagination.
Back to the list of great writing on photography, I'm sure I've overlooked some and will post again if my my memory clears.
Sean