fact checker:
Thank you, those are good points. Yes, I certainly agree that "analyzing data and finding sources of error, relevance to conclusions...are valuable skills that transfer to more than just a career."
I included two graphs because they capture snapshots for entering college freshman (SAT) and graduating seniors (GRE). There are valid concerns about what they actually measure (see MarcusM's argument that they largely correlate with socioeconomic status), but set that aside for the moment.
Let's focus on the key issue that you rephrased: the usefulness of a BS degree in Medieval History for future employment. First, as noted ad nauseam in earlier posts, I disagree with the central premise that the primary purpose of a university degree is for job training, but let's also set that aside, and argue on your own terms.
You are astute to notice that those plots show "GRE scores based on INTENDED major for grad school", so you state that they are largely irrelevant for employment in non-academic job markets, and thus detract from my other points. Right? Is that a fair restatement?
My argument here is that part of the financial value of a degree rests upon its signalling value to employers, who prefer smart and hard working kids. Those plots show several liberal arts majors as belonging in the upper quadrant, at least in terms of average intelligence, and hence as attractive future employees. (The scores do not directly measure hard work.) It's relative position vis-a-vis other majors that counts.
My chain of reasoning depends on the assumption that the relative position of those GRE scores are proxies for all students in a given major, not just the ones motivated to apply to grad school. I may be right or wrong on that; it's an empirical question for which I do not have the data.
To be fair to my side, I never stated that "$100k for a Medieval History degree is money well spent for the average 18 year old", with the operative word being "average." That's a strawman argument. As the posters "800 dude" and "hold the phone" put it so well, "Do what you're interested in, but just make sure you do it to the maximum of your ability."
There is another way to approach the question whether a degree in Medieval History, or some other esoteric liberal arts degree, is detrimental to future employment prospects. Consider the case of St. John's College, a great books school with campuses in Annapolis and Sante Fe. St. John's curriculum (which I love -- check it out online) makes medieval history look crassly practical. You can look up the statistics for their alumni placement outcomes -- they are pretty good; their graduates get jobs. (For the love of g*d, I don't have the time to be more precise than that, i.e. to do or reference a proper statistical study vs. other colleges.)
Finally, we should acknowledge that this entire subject is part of an old and interminable debate on the purpose of education and is unlikely to be settled in the message boards of a running forum. Reasonable and civil discussion even with the occasional zinger is, however, the hallmark of a liberal arts education.