Chicken and Egg

CORE DEFINITION

The chicken-and-egg causal dilemma expresses the question of which came first, the chicken or the egg. This problem has often inspired ancient philosophers to explore and discuss the origins of life and the universe. In general, people tend to think that finding an answer to such circular causality questions is futile, considering them among the most fundamental questions in nature. Of course, the literal answer to this question is simple and obvious: egg-laying animals existed long before chickens appeared. However, the metaphor behind this simple question brings about a metaphysical dilemma. To better understand this dilemma, the question is often reformulated as: "X gets Y, Y gets X, so which came first, X or Y?" This question is also often applied equivalently to circular reference problems in engineering and other disciplines, such as a parameter that requires calculating itself to be obtained. Examples of such cases include the van der Waals equation and the famous Darcy friction factor calculation formula.