A well-thought-out example, that may serve as a good model for a course on mathematics for humanities students, is Gerald Holton and Stephen G. Brush's Physics, the Human Adventure: From Copernicus to Einstein and Beyond (Rutgers University Press, 2001). It's the third edition of Introduction to Concepts and Theories in Physical Science (Addison-Wesley, 1952).

Holton and Brush is not intended to be an "easy" book. The authors write in the preface, "The book is intended for a year course (two semesters or three quarters) in a general education or core program, taken primarily by nonscience majors who have an adequate background in mathematics (up to but not including calculus)" (xiv). The goal of their book is to present "a comprehensible account -- a continuous story line, as it were -- of how science evolves through the interactions of theories, experiments, and actual scientists. We hope the reader will thereby get to understand the scientific worldview. And equally important, by following the steps in key arguments and in the derivation of fundamental equations, the readers will learn how scientists think" (xiv; emphasis in original).

One of the features that makes Holton and Brush unique is that the book makes use of both the history and the philosophy of science to create the story line. A course on mathematics for humanities students ought to make use of the history and philosophy of mathematics for similar reasons. Doing so creates a context for students so that they can learn how mathematicians think.