John B. Ridpath, Ph.D. (//; born 1936) is a Canadian Objectivist intellectual historian and retired associate professor of economics and intellectual history at York University in Toronto. He also taught courses at Duke University. He attended Toronto's Upper Canada College (Head Prefect, 1955) and then later the University of Toronto, from which he received both an undergraduate degree in Engineering and an MBA, while also setting Canadian national swimming records and captaining the University of Toronto swim team. Although he obtained his doctorate in economics from the University of Virginia (1974), he works in the area of intellectual history, focusing on the power of philosophical ideas in Western social history. As an academic, despite receiving an award by the Ontario Council of University Faculty Associations for outstanding contribution to university teaching, he was nearly terminated in the early 1970s for his radical outspoken views and his avowed disdain of much of York University's faculty. However, with support from Nobel laureate Friedrich von Hayek, he was promoted rather than fired. Upon his retirement in 2001 he was named professor of the year by the university and honoured with a nomination for Canadian professor of the year.
He has served on the board of directors of the Ayn Rand Institute since the early 1990s and his writing has appeared in academic publications and in The Intellectual Activist. He is an expert on the history of the founding of America and on the Founding Fathers of the United States. During his career he has defended the morality of capitalism against socialism in debates on college campuses across North America including Yale University, Harvard University, the University of Chicago, UCLA and Berkeley, and notably against former premier of Ontario Bob Rae. He continues to lecture in Europe and North America.