I don't really understand what you are asking for. Do you need published reference material to form an opinion for your paper, because you do not know why people use film, or do you already have your opinion, and just need to find interesting passages to quote?
For me, the philosophy of using film is not very deep, if existent at all. I guess the most philosophical thing about it is that I generally prefer to work with tangible physical media than with purely electronic digital media, be it in the area of music, photography, writing, etc. Aside from the physical differences in process, I feel that working strictly with something that is held in the hand is an important difference. I don't know if that is "philosophical." Perhaps just something that lubricates my imagination in an intangible way (perhaps because it is, quite simply, much more fun)...
Other than that, the differences all come down to results, equipment, cost, and process all very physical and tangible things. Not much philosophy there.
Here is my personal favorite Internet article on why we use film:
http://www.kenrockwell.com/tech/why-we-love-film.htm.