Philosophy is now a subject in the humanities within the college curriculum. Its primary purpose is to study and develop systematic habits of thought that will enable students to recognize and evaluate their own life choices and understand the society in which they live. Because so much of philosophy focuses on ideas, beliefs, and values, it is rather easily connected to literature and projects in contemporary cultural criticism and analysis in other fields. Toward the end of the twentieth century, philosophers began to apply their work to other fields, for example via medical ethics and business ethics. The relevance of philosophy also increased as philosophers added feminism, environmental issues, and questions about social justice to their curricula.