On Sunday night, supporters of Lexington’s Fairness Ordinance were scheduled to gather downtown to celebrate the 20th anniversary of what was then a groundbreaking proposition to ban discrimination against gay people in hiring, housing and public spaces. But many of them will also be mourning one of the groundbreakers, University of Kentucky professor emerita Joan Callahan, who died June 6 after a long battle with cancer. She is survived by her wife, Jennifer Crossen, her son, David Crossen, and two grandsons. Callahan was an esteemed academic, a philosophy professor who specialized in gender and ethics and directed UK’s women’s studies program, helping turn it into the gender and women’s studies department. She was also a civil rights warrior, who with Crossen, worked to make Lexington a more diverse and accepting city in both law and attitude.