Am I a doctor or not?

Having a doctorate in the Humanities (a Doctor of Philosophy, but a historian) can pose a dilemma, albeit an egotistical one. When I book a room at a hotel, reserve a table for dinner at a fine restaurant, or subscribe to any number of journals, magazines, or newspapers, do I refer to myself as "Dr.?" Medical doctors are assumed to use their titles for such things (I believe it says so on their driver's license). I have had people ask me what type of medicine I practice, and for some unknown reason I sheepishly reply that "I'm not that type of doctor" and almost feel guilty for using the title. In turn, they look at me in a way that says, "oh, so you're not a REAL doctor."

Yet why should I be reluctant to use the title that took me seven years of sacrifice and work? Is it the American in me, that silly scorn of titles and hierarchy, that fear that such things establish a de facto aristocracy? A friend of mine, an American theologian educated in Austria, regales me with tales of how students and average citizens honor doctors of philosophy and letters in Europe -- he knew of one professor who had two doctorates and was referred to as "Dr., Dr."

What is the etiquette for such things in America? Are the only doctors ones who perform surgery, or also those who lecture on Plato? Of course, my fear is that one day I will reserve a table at a restaurant as a doctor, another patron will choke or have a heart attack, and everyone will expect me to assist and save the day. The best I'll be able to do is hold the poor man's hand and tell him about Abe Lincoln while he dies.