interesting... i was in the same boat once, my undergrad major was philosophy of science, i was always pre-med, but the more i got into philosophy the more i liked it, and i did consider the phd in philo. for a while. i also thought a lot about biomedical ethics which is a good hybrid between the two, upenn has a good site on this topic. ultimately i got into research, and thought about the phd in the medical sciences, but although i've been accepted for a phd at a top school, as well as d.o. schools, i feel that i can do research, or even postgrad. training in med. ethics as a d.o., but as a phd, i can never see patients, so if you're confused go for the career that gives you the most options...