Most adults can learn a new language in ~6 months; the real test is how much substance is in each topic. Anyway the real joke about Phd's in Literature has to do with the perception that it's total BS. The great example of this is so-called ‘postmodern generator’ written by Andrew C. Bulhak using the Dada Engine, a system for generating random text from recursive grammars. Using this software (http://www.elsewhere.org/pomo) NYU Physics Professor Alan Sokal’s generated a brilliantly meaningless article which was accepted by a cultural criticism publication, Social Text Vol. 46/47, pp. 217-252 (spring/summer 1996). (Sokal, A., 2007, http://www.physics.nyu.edu/faculty/sokal/, accessed May 13, 2007)

PS: However, the same could be said for CS depending on your standards for quality (http://pdos.csail.mit.edu/scigen/).