The liberal arts include the sciences, and the sciences make use of the approaches the humanities bring to observation and inquiry. 

The author writes:

The idea that STEM is something separate and different than the liberal arts is damaging to both the sciences and their sister disciplines in the humanities and social sciences. The value of a liberal arts education is not in the content that is taught, but rather in the mode of teaching and in the intellectual skills that are gained by learning how to think systematically and rigorously.