You said he likes liberal arts and the sciences. Then you made it more specific and said he mainly likes political science and philosophy.
First of all is he only getting a 4 year degree? For example lots of law students have a B.A. in political science and philosophy. However I would be skeptical going to law school, there's a lot of people going into law school and lots of lawyers are unemployed right now.
If he's only going to get a 4 year degree, has he ever taken a class on economics? Economics is a social science, but it also requires calculus so it's practical as well. He could become a stock broker or something with an econ degree or get into business.
Does your partner hate math? If he absolutely despises math and refuses to take calculus (even though in my opinion everyone could do calculus and pass it) then perhaps he should consider getting a degree in accounting? Accounting is a great 4 year degree, in my opinion it's one of the best. It arguably may be even better than an engineering degree, as long as he gets his CPA (Certified Public Accountant).
Also just a side note, I understand you being concerned about what he's going to major in, but I would also take some time to do research. For example, a few days ago I just read a news article on the "Best paying 4 year degrees in 2011" and although polici and philosophy weren't in the top 20, economics was. Furthermore, the article even said that right now according to the stats they have, poli sci and philosophy degrees are better paying than a standard business degree.
Also contrary to conventional wisdom, 4 year degrees in the hard sciences like biology, chemistry, biochem, and physics aren't good 4 year degrees. Apparently the problem with the hard sciences is that everyone these days just wants someone at least with a masters, preferably a PHD. People with 4 year degrees in the hard sciences end up doing some crappy tech job that pays like $10-$15 dollars an hour.
I'm just pointing this out, because I think there's lots of misconceptions about what bachelor degrees are good and what aren't. If I were you and I were really serious about this, I'd do some research before jumping to conclusions.
EDIT: If he isn't a realist, why doesn't he go beyond a bachelors in whatever he's interested in? He could get a PHD in philosophy or poli sci and become a professor. Professors get paid pretty decently and they get benefits to.
I'm not saying professors aren't realists, but being a "realistic" person isn't exactly a necessary trait to have to be a professor compared to say a career like being an accountant or businessman which requires being realistic.