The liberal arts are those disciplines, which, when mastered, enable a man or woman to be truly free – free to think, free to know truth (because they have been taught to employ logic/sound reasoning and to analyze arguments and see the truth about them), free to employ language without the limitations of the uneducated.
The liberal arts are called the “liberal” arts because they are both the arts that every free person is free to master and the arts that are required to be free. A community that fails to master the arts of the trivium cannot be a free community. For example, he who is not a master of the art of logic is a victim of manipulators, both external (in society) and internal (in the soul), while he who is not a master of the art of rhetoric will be unable to express his thoughts appropriately.
(these thoughts are summarized from classical Christian educator Andrew Kern)