Biologic plausibility supports causation through what mechanism?

Biologic plausibility supports causation by offering a reasonable biologic or physiologic mechanism that explains how one factor could influence another. This understanding comes from established biological or physiological principles, which help to validate the relationship between the factors in question. For example, if a study finds that exposure to a certain chemical is associated with an increased risk of a health condition, biologic plausibility would involve understanding the chemical's effects on biological processes that could lead to that health condition. Such mechanisms lend credence to the idea that the observed correlation is not merely coincidental, supporting the argument for causation.

In contrast, while correlation between two variables can suggest a relationship, it does not provide the necessary mechanism to affirm causation. The absence of alternative explanations can strengthen arguments for causation, but without a plausible mechanism, such arguments may fall short. Similarly, a statistically significant result indicates that findings are unlikely to be due to chance, but without understanding how one variable affects another biologically or physiologically, causation remains unsubstantiated. Thus, having a reasonable mechanism to explain why a causal relationship exists is essential for establishing biologic plausibility.