In epidemiology and biomedicine, biological plausibility is the proposal of a causal association—a relationship between a putative cause and an outcome—that is consistent with existing biological and medical knowledge.
Biological plausibility is one component of a method of reasoning that can establish a cause-and-effect relationship between a biological factor and a particular disease or adverse event. It is also an important part of the process of evaluating whether a proposed therapy (drug, vaccine, surgical procedure, etc.) has a real benefit to a patient. This concept has application to many controversial public affairs debates, such as that over the causes of adverse vaccination outcomes.
Biological plausibility is an essential element of the intellectual background of epidemiology. The term originated in the seminal work of determining the causality of smoking-related disease (The Surgeon General's Advisory Committee on Smoking and Health [1964]).