What is the relation between liberal education and getting trained for a professional career? By definition, they are very different things. In fact, they are usually defined in opposition to each other. A programme of liberal study is a foundational engagement with a subject for the sake of advancing knowledge, without any specific job, vocation or career in mind. A professional programme is training for a specific kind of career. To be liberal, in the curricular sense of the term, is to be open to all possibilities, and not directed at just one; to be professional is not so much to study subjects for their own sake, but to do so with the structured goal tied to a specific kind of career.
The difference is not so much one of content, but of approach. Similar subjects can be a liberal or a professional subject, depending on how they are curricularised and/or taught: biology is a liberal art, but medicine is not; political science is a liberal art, but law is not; economics is a liberal art, while accountancy is not. The “art” of the “liberal arts” is, of course, an anachronism—it freezes the historical memory of a time when all subjects were considered arts, including those now considered part of the sciences, such as mathematics. Nearly any disciplinary field, the critic Louis Menand, points out, can be turned into liberal or non-liberal depending on its association with adjacent practical skills. English departments can become writing or publishing programmes; pure or abstract mathematics can merge into applied mathematics or engineering; sociology holds the promise of social work just the way biology holds the roots of medicine; political science and social theory offers the foundations of law and public administration.