I have a question about the kind of experience, academic background, etc. required for book-length nonfiction writing. I wrote my undergraduate thesis on post-apocalyptic literature and recently wrote an article for a popular sci-fi blog on why we like the apocalypse, which got something like 20,000 views and has helped make my blog (which has other nerdy apocalypse stuff) pretty popular. A lot of commenters have been asking for my thesis and encouraging me to publish it, which is flattering, of course, but who wants to read a book by someone who only has a B.A.? As a reader, I would definitely be suspicious of the author's credibility. Obviously, if I went off for 8 years, got a PhD, and came back to the topic, anything I'd write would be much better, but I don't think what I have to say now is valueless, either - I think it's pretty cool, actually, and I know that there are some science-y writers (like Mary Roach) who've successfully built a career without an advanced degree. So my question to you is: would any publisher look twice at a proposal by someone like me who's armed with such a short (but focused) resume?
Here's how I look at a query in terms of higher education credentials:
(1) Fiction - no credentials needed if book is good
(2) Memoir, "learn from experience"-type non-fiction - no credentials needed if book is good, but probably shouldn't come out of nowhere (i.e. you should have some real-world credentials of some kind, even if they're not academic)
(3) An academic book - requires some credentials. These are not necessarily "PhD in your area." You don't need a PhD in international relations to write about international relations; you need some experience in the IR field, maybe a posting or a job or field work combined with publications in journals. If you're writing about an area of medicine and it's not your medical memoirs, you should have some kind of medical credentials, preferably an MD in your field, but we do get a lot of submissions by social workers, nurses, and medical professionals who did not attend a full course of medical school. In other words, if it's a highly technical book, you need some excuse to have the authority to write it.
If your thesis is good, and you felt compelled to turn it into a book, I would look at it if the query letter was good. I'm not clear on your field here, but I'm not even sure you can major in the apocalypse, much less get a PhD in it, but I guess my answer is yes, I would look at your query and not toss it because you don't have a master's.
One area where people generally do not have academic credentials is historical fiction. I have a BA in history but decided not to pursue a masters or PhD because of the nature of academia. Though many writers have some sort of "background" like the one I've described, the majority of their material is derived from private research, scouring libraries and interviewing experts, not sitting in a PhD program preparing a thesis that by definition has to be as boring as possible (I was once graded down for my paper being "too dramatic). If it sounds like they know what they're talking about, I don't look for historical fiction authors' credentials at all.