Seriously!
Deepak Chopra has.
There’s one. Not exactly convincing proof, is it? 
p.s. On second thoughts, it proves if one can, so can others. I know I got the response I deserved, and if I wanted more details I should have been more specific in my OP. Please forgive my vagueness.
A small number of people make a living teaching philosophy. There might be a very few positions at think-tanks or outfits like the CIA where a philosopher might be employed as one element of a larger project.
They write. I suppose you could count some monks, too. And probably coaches, these days.
But, can you make an honest living as a philosopher?
The professors of philosophy that Tom Tildrum mentioned are one example. To be teaching at a university, they also have to be publishing articles and books on philosophy, so they’re doing more than just teaching - they’re expanding the field of written works of philosophy. So yes, between teaching and writing, they are making reasonably good livings from philosophy.
Plus, depending on the field of philosophy, what they do may have some relevance to other fields. The logicians and philosophy of math guys find that their work is of interest to computer programmers and mathematicians; political philosophers get calls for their participation by poly sci academics; ethicists and moral philosophers may find they get consulted by corporations on occasion that are grappling with issues of business ethics, or by health care agencies that are dealing with issues such as quality of life v. duty to treat a patient, and so on.
(My brother actually happens to be a philosophy prof, so he’s mentioned things like this from time to time.)
Yes, as a professor of philosophy. Teaching is part of the job, but teaching isn’t what would get you hired nor would be be what you were getting paid for. You would get hired for being a really good philosopher who has written and will write significant works of philosophy.
Now then, there aren’t many of these jobs and they aren’t easy to get. But they do exist.
Coincidentally, here is a somewhat snarky article about the job market for philosophy graduates.
Are you thinking outwith academia? Any sizable university will have a philosophy dept, so there’s obviously going to be numerous philosophers employed here. Indeed, this is where all the serious philosophising in society will take place. Unless they are independently wealthy, any philosopher of note will have a university appointment.
Outside of Schools of Learning, then you’re into murky definitions of ‘popular philosophy’ - are Deepak Chopra, Alain de Boutton and people of similar ilk philosophers? Not in my parish, but others may disagree. There is certainly a (large) appetite for lightweight, easily digestible musings on existance, thought and the like that sustains the bank balance of these personalities.
You can certainly make a living, and then some, having studied philosophy as a degree subject. You won’t be a philosopher as such, but it’s clearly a highly rigorous, analytical and taxing discipline that only the most capable can excel in.
I’ve often heard that philosophy is a good undergrad choice for people planning on going to law school, since law school demands the same kind of thinking.
Perhaps William Irwin, who’s edited most of those books in the Open Court and Blackwell series called “Popular Culture and Philosophy” has made enough from editing those books that he could live on that alone (although in fact he teaches philosophy at a college). Perhaps Robert Pirsig, who wrote Zen and the Art of Motorcycle Maintenance made enough money from that book to live on.
I love this introduction from the philosopy department at a major university:
I’m not entirely sure of that. As a physics/philosophy dual major in undergrad, I nearly failed the one law course I took. Partly due to lack of focus, but also partly due to my inability to stop thinking like a philosopher. One instance that leaps to my mind comes from a discussion of federal racial discrimination statutes, where the professor told us that an individual could count as a member of a minority if at least one of their grandparents was a member of that minority. And all I could think about was to wonder how to tell if the grandparent was a member of the minority. 
Yes, of course you can; as everyone has said, join the philosophy department at any major university. Teaching will likely be a component of your job, but mainly, you will be there to do research and write papers, same as any other member of academia. We actually have some professional philosophers on this board, in fact (e.g., Sophistry and Illusion, I believe).
No you Kant!
An engineer asks “How?”
A scientist asks “Why?”
A philosopher asks “Do you want fries with that?”
Oh wait - you said “seriously”. Another old joke suggests that Deepak Chopra might really be a philosopher after all.
A philosopher and a mathematician were discussing their work. The mathematician says, “all I need is a pencil, some paper and a waste paper basket.” The philosopher replies, “it’s the same for me except I don’t need a waste paper basket.”
You can, if you think you can.
From Severn Darden’s Metaphysics Lecture.
While you wait for someone to design Earth, you could probably make a few bob.
This. A “professor of philosophy” is every bit a “professional philosopher”, just as a “professor of physics” is a “professional physicist.”
I suppose the other option would be if you could write some really popular books on your philosophy. A professional writer whose writing consists of original philosophical works should be considered a “professional philosopher”, I think.
I would say there are three possible options for making a living as a philosopher:
-
Academic philosophy professor, as discussed above - write papers, teach classes. I have a relative who does this. He’s the most [del] argumentative[/del] debate-oriented person I know.
However, from what I’ve seen on the Dope, ivan, you may also be cut out for this field. Only you can say for sure. -
Philosopher to another field -
a) Philosophy of medicine, one is now teaching ethics at a medical school (poorly, if my experience is the yardstick)
b) the old theory that business / law / google needs philosophers for their expertise in thinking - I find this unlikely in a era of belt tightening.
c) most Philosopher of X types are still going to be at universities, as in point 1. I know a Philosopher of Science guy who hangs out with scientists, but only coincidentally, it has zero to do with informing his work. -
Pseudo-philosopher or enlighted one, selling homespun wisdom to the masses.