Barkun has classified conspiracy theories into three kinds:
Event conspiracy theories. This refers to limited and well-defined events. Examples may include such conspiracies theories as those concerning the Kennedy assassination, 9/11, and the spread of AIDS.
Systemic conspiracy theories. The conspiracy is believed to have broad goals, usually conceived as securing control of a country, a region, or even the entire world. The goals are sweeping, whilst the conspiratorial machinery is generally simple: a single, evil organization implements a plan to infiltrate and subvert existing institutions. This is a common scenario in conspiracy theories that focus on the alleged machinations of Jews, Freemasons, Communism, or the Catholic Church.
Superconspiracy theories. For Barkun, such theories link multiple alleged conspiracies together hierarchically. At the summit is a distant but all-powerful evil force. His cited examples are the ideas of David Icke and Milton William Cooper.
Barkun discusses four types of groups categorized by the nature of secrecy involved: a Type 1 conspiracy theory refers to a secret group which acts secretly, and a Type 3 conspiracy theory refers to a known group which acts secretly.
Education
Barkun earned his Ph.D. from Northwestern University in 1965.
Works
United Nations System and Its Functions: Selected Readings. Published in Princeton, NJ by Van Nostrand as a 460-page hardcover and paperback. A part of the Van Nostrand political science series.
Law Without Sanctions: Order in Primitive Societies and the World Community. Published by Yale University Press as a 179-page hardcover.
International Law and the Social Sciences. Published by Princeton University Press as a 338-page hardcover.
Social Science Literature: A Bibliography for International Law. Published in Princeton, NJ for the American Society of International Law by Princeton University Press as a 662-page hardcover. It was republished in paperback in 2015 as part of the Princeton Legacy Library series.
Law and the Social System. Published in New York by Lieber-Atherton as a 128-page hardcover and paperback.
Disaster and the Millennium. Published in New Haven by Yale University Press as a 246-page hardcover. It was re-published in paperback in 1986 by Syracuse University Press.
Crucible of the Millennium: Burned-Over District of New York in the 1840s Published by Syracuse University Press as a 194-page hardcover and paperback.
Millennialism and Violence. Published in London and Portland, OR by F. Cass as a 177-page hardcover and paperback. It was the second in the Cass series on political violence.
Culture of Conspiracy: Apocalyptic Visions in Contemporary America. Published in Berkeley, CA by University of California Press as a 243-page hardcover. It was the 15th book in the Comparative Studies in Religion and Society series. A 251-page paperback edition was published in 2006. A second edition was published in 2013 as a 320-page paperback.
Chasing Phantoms: Reality, Imagination, and Homeland Security Since 9/11. Published by The University of North Carolina Press as a 208-page hardcover. A paperback edition was published in 2014.