First off, I think some discussion of terminology is in order. When people talk about "liberal arts majors" in modern colleges, they generally seem to mean people who major in English, History, Philosophy, Art, Religious Studies, etc. Thus, in disputes about education, you'll sometimes hear someone say something along the lines of "You want a liberal arts education? Go to the library if you want to read the classics!" Or some particularly easy general math or science course will be dismissed as "for liberal arts majors" when talked about by students actually majoring in Mathematics or in one of the sciences. However, even in current formal usage, "liberal arts" still designates a wider range of skills than this more colloquial usage. Miriam-Webster defines "Liberal Arts" thusly:
1. the medieval studies comprising the trivium and quadriviumI rather like Google's definition for conciseness:
2. college or university studies (as language, philosophy, literature, abstract science) intended to provide chiefly general knowledge and to develop general intellectual capacities (as reason and judgment) as opposed to professional or vocational skills
1. Academic subjects such as literature, philosophy, mathematics, and social and physical sciences as distinct from professional and technical subjectsThis range of disciplines reflects the original list of the Seven Liberal Arts which derives from the 5th Century Roman writer Martianus Capella: Grammar, Logic, Rhetoric, Arithmetic, Geometry, Music, Astronomy
To the modern eye, this seems like a wide and somewhat odd collection of skills, and I would not say that a modern liberal arts education should necessarily mirror the original Seven Liberal Arts in exact detail. However, I think there is a useful general point do be derived from them. The seven liberal arts represented the education of a generalist. It was an advanced education. In late antiquity someone getting a liberal arts education would have mastered both Latin and Greek, and gained the ability to write and speak fluently in a variety of genres: Political speeches, poetry, history, etc. The student would have mastered formal logic and the major philosophical schools of the time, including an understanding of science (natural philosophy), ethics, and metaphysics. The student was also expected to master mathematics and geometry at a fairly high level. If you've worked a bit of Euclid, this wasn't exactly "math for liberal arts majors", it's fairly hard core stuff. And the modern equivalent of Music and Astronomy as the Ancients dealt with them would arguably be the hard sciences.
What made these "liberal arts", the skills of a free man? Some of these related directly to the responsibilities of a citizen taking part in ancient civic life: rhetoric, for example, was key to the political campaigning and legal wrangling which was a common part of aristocratic life in antiquity. More broadly, however, these are general skills. Someone who has only a specialist's education in some given trade is thus limited to his chosen profession. He is, in some sense, educated to be an implement. An education in the liberal arts is suited to a free man because they provided a general foundation on which one can quickly develop a more practical expertise on any of a number of subjects. So the liberal arts are those skills suitable to a free man because they are adaptable, allowing him to turn to any of a number of subjects and have sufficient knowledge and adaptability to master them.
Further, the idea of a liberal arts education is based on an understanding of the human being as a rational creature. We have a human need to understand questions of "why" and "ought", not just "how". As such, it's suitable to the human person to develop the skills that allow us to reason about the human condition and about the problems we face in our lives and in society at large.
The liberal arts are skills that provide us with the ability to understand the things that surround us and reason about them. As such, some degree of liberal arts are (at least if we take seriously the idea that we all share a human dignity rather than being by nature either "servile" or "ruler" in type) necessary skills for all of us.
What that leaves open is the question of what relation (if any) the liberal arts bear modern education at various levels, and since I've already spent far too much time on this post, I'll try to begin addressing that in another post.