In this episode, we unpack the "domino theory," a defining geopolitical concept of the 20th century which posited that if one country fell to communism, its neighbors would inevitably follow in a chain reaction. We trace the theory's origins from President Harry S. Truman’s aid to Greece and Turkey to its popularization by President Dwight D. Eisenhower in 1954, who famously warned that knocking over the first "domino" in Indochina would lead to widespread disintegration,.

We discuss how this metaphor became the primary justification for U.S. intervention in Vietnam under the Kennedy and Johnson administrations,. The episode examines historical arguments supporting the theory, such as the 1975 communist takeovers of South Vietnam, Laos, and Cambodia, as well as the counter-evidence, including the CIA’s skepticism in the 1960s and the failure of communism to take root in Indonesia and other parts of Southeast Asia,.

Finally, we explore the theory’s lasting legacy, including former Secretary of Defense Robert McNamara’s admission that the policy was a "mistake", and how the concept evolved into the "democratic domino theory" regarding the Middle East and modern Russian fears of "color revolutions",.

Analogy: You can think of the domino theory like a forest fire jumping between trees. The theory assumes that because trees (countries) are close to one another, if one catches fire (ideological change), the heat and sparks will inevitably ignite the trees immediately next to it, necessitating a "firebreak" (containment) to stop the entire forest from burning down.