Philosophy is in danger of becoming the preserve of "leisured gentlemen" as post-1992 universities scrap courses because of dwindling student numbers.
Three new universities have decided to close philosophy courses in the past two years, while others have axed plans to introduce degrees in the subject.
The closures are significant as less than a third of new universities - just 19 out of 64 post-1992 institutions - ran undergraduate philosophy programmes last year.
The University of Bolton decided to close its BA in philosophy in 2007 because of low application rates.
University College Plymouth St Mark & St John scrapped its course for the 2008 intake, citing a "lack of interest in the subject".
Roehampton University announced recently that it would no longer accept new students for its single honours course in 2010, and the University of Gloucestershire has pulled the plug on plans to launch a BA in the subject.
Paul Hartley, deputy vice-chancellor (academic) at Gloucestershire, said the decision had been taken on the basis of market research, which "concluded that the potential student pool was not sufficiently large to merit investment".
Helen Beebee, head of the department of philosophy at the University of Birmingham, said the closures risked limiting the subject to a small, homogeneous group of students.
"It would be a real pity if the study of philosophy was restricted to the standard 'old-university' demographic - white, middle class, with good A-level grades," she said.
Julian Dodd, professor of philosophy at the University of Manchester, agreed that single honours philosophy was increasingly the preserve of old universities.
He said: "It's less easy than it was to admit students from unconventional backgrounds."
Professor Dodd, who previously taught at Bolton, said the introduction of tuition fees had caused problems for philosophy courses at new universities. "The bottom just dropped out of the market when fees and loans came in. That very local, mainly working-class market contains those people who do not like to be put into debt."
Stephen Mumford, professor of metaphysics at the University of Nottingham, studied philosophy as an undergraduate at the University of Huddersfield, which was then a polytechnic.
Huddersfield withdrew its philosophy major in the early 1990s.
Professor Mumford said the research assessment exercise had briefly "democratised" the subject, "in that someone who had graduated from Huddersfield could get a job if they had sufficient publications behind them".
"But it was a very brief window for people like me," he said. "I have no doubt that if I were young now, from a working-class background, having to take a big student loan would prevent me from studying philosophy because of the sense that it's non-vocational."
He added: "We could end up back in the days when it was only the leisured gentlemen of the country who could afford to do it.
"As many employers realise, philosophy graduates are some of the best graduates. The country needs people who can think analytically and who are not going to be fazed by a dense piece of argument."