Republican presidential candidate and neurosurgeon Dr. Ben Carson will address the newest graduates of Grove City College during Saturday’s commencement, according to a news release from the college. Carson is filling in for conservative author William Bennett, who was scheduled to speak but had to decline unexpectedly. The college also will present an honorary Doctor of Science degree to Dr. Carson during the ceremony, in recognition of his contributions in advancing medical science. Commencement is slated for 10 a.m. Saturday on the Quad on the campus of Grove City College.