I was a phil major and am a photographer. I would say it depends on the course content. A class like analytic philosophy can be difficult. If the phil class you're looking at is an intro course, I would say take phil over photo if you've got a busy semester. Photography can take up a lot (more like A LOT) of time, especially if you're using fiber paper instead of RC paper. For fiber paper, it takes 6.5 minutes just to get one print done. This time is the time in the chemistry. There's also the time spent at the enlarger, and then there's time doing a test strip before you do your full print. If the print ends up not the way you want it to look, you have to go back and redo the print. There have been days I've spent over 4 hours in the darkroom and only ended up with 3 workable prints to show for it. Although that's more like what a bad day is. Good days, I can get 6 prints in 2 hours. In addition to darkroom time, there's shooting time to account for and film developing time. If you've never developed film before, it's going take you at least a couple of times doing it before you get the hang of it, which means initially more time out of your schedule. In phil if you've got a good lecturer, you could probably get by without doing some assigned readings and you'll probably have two exams for the semester and one or two papers, which is not bad at all. And since you said it was an intro course, it should be quite easy. When you start getting into the obscure stuff taught in upper level courses, then it can be murder. With all that in mind, take the class you're interested in more. Don't let the time consumption scare you off photography. After all the hard work, good results are very rewarding. For me, being in the darkroom is relaxing. It's dark and quiet, and with water running in the wash in the background, it's very calming. It's a form of stress relief for a lot of people I know.
Edit: Contrary to popular belief, you do not need expensive equipment for photography. A camera is just a box with a hole in it to let light in. I've gotten some pretty fun prints with my cheap $20 Holga as well as my $1000 Canon. And since everyone is going digital and selling all their film cameras and film developing equipment (pretty stupid if you ask me), you can get some great used film cameras for dirt cheap. The late 70s and early 80s is a great era for film cameras. If you take care of your camera, it'll last you forever. Although, a warning: Do not buy off eBay. You might get cheated and end up buying a camera that has problems with the shutter or something else, and there won't be anyone in town who has the equipment to fix it. If anything that's expensive in photography, it'll be the paper and film. With film, you should be shooting at least 2 rolls a week if you want good choices with which to print. Fiber paper is more expensive than RC, and the bigger the paper, the higher the cost. Fiber at 8x10, the size you'll usually start off with, is about $1 or $2 a sheet, depending on how good of a supplier you've got.