During his time at Marischal, Campbell was a founding member of the Aberdeen Philosophical Society along with philosopher Thomas Reid, John Gregory (mediciner), David Skene, John Stewart and Robert Trail. Many members of the Society, including Reid, Campbell, and Gregory, were great admirers of Francis Bacon, so the group's aim directed toward the exploration of the sciences of the mind. The Aberdeen Philosophical Society is most often remembered for its philosophical publications, notably: Reid's "Inquiry into the Human mind, on the Principles of Common Sense" (1764), James Beattie's "Essay on the Nature and Immutability of Truth" (1770), and Alexander Gerard' "Essay on Genius". Campbell's work was very much influenced by the group's members. "The Philosophy of Rhetoric" was originally read in discourses before this Society. Campbell's emphasis on the trustworthiness of the senses and his exploration of tendencies basic to human nature have been attributed to the influence of his colleague in the society, the common sense philosopher, Thomas Reid.