Chicken or the egg

Illustration from Tacuina sanitatis, Fourteenth century

The chicken or the egg causality dilemma is commonly stated as "which came first, the chicken or the egg?"

Chickens hatch from eggs, but eggs are laid by chickens, making it difficult to say which originally gave rise to the other. To ancient philosophers, the question about the first chicken or egg also evoked the questions of how life and the universe in general began.^[1]

Cultural references to the chicken and egg intend to point out the futility of identifying the first case of a circular cause and consequence. It could be considered that in this approach lies the most fundamental nature of the question. A literal answer is somewhat obvious (the eggs came first), as opposed to the logical fallacy of the metaphorical view, which sets a metaphysical ground on the dilemma. So, to understand its metaphorical meaning better, it could be reformulated as follows: "Which came first, X that can't come without Y, or Y that can't come without X?"

An equivalent situation arises in engineering and science known as circular reference, in which a parameter is required to calculate that parameter itself. Examples are Van der Waals equation and the famous Colebrook equation. Another example is calculation of thickness of roof of a tank or structure. To calculate the thickness requirement, we need to know the self weight of the roof, which is possible only by already knowing the thickness. This situation is solved by initially assuming the parameter and by repeated iterations converging towards finer values.

History of the dilemma

A chick hatching from an egg

Ancient references to the dilemma are found in the writings of classical philosophers. Their writings indicate that the proposed problem was perplexing to themselves and was commonly discussed by others of their time as well.

Aristotle (384-322 BC) was puzzled by the idea that there could be a first bird or egg and concluded that both the bird and egg must have always existed:

If there has been a first man he must have been born without father or mother – which is repugnant to nature. For there could not have been a first egg to give a beginning to birds, or there should have been a first bird which gave a beginning to eggs; for a bird comes from an egg.

The same he held good for all species, believing, with Plato, that everything before it appeared on earth had first its being in spirit."^[2]

Plutarch (46-126 AD) referred to a hen rather than simply a bird. His is Moralia in the books titled "Table Talk" discussed a series of arguments based on questions posed in a symposium. Under the section entitled, "Whether the hen or the egg came first," the discussion is introduced in such a way suggesting that the origin of the dilemma was even older:

...the problem about the egg and the hen, which of them came first, was dragged into our talk, a difficult problem which gives investigators much trouble. And Sulla my comrade said that with a small problem, as with a tool, we were rocking loose a great and heavy one, that of the creation of the world..."^[3]

Macrobius (395–423 AD), a Roman philosopher, found the problem to be interesting:

You jest about what you suppose to be a triviality, in asking whether the hen came first from an egg or the egg from a hen, but the point should be regarded as one of importance, one worthy of discussion, and careful discussion at that."^[4]

Stephen Hawking and Christopher Langan argue that the egg came before the chicken, though the real importance of the question has faded since Darwin's On the Origin of Species and the accompanying Theory of Evolution, under which the egg must have come first, assuming the question intended the egg to mean an egg in general or an egg that hatches into a chicken.^[5][6]

Responses to the dilemma

Definitions

In biology, the term egg is biologically ambiguous and the theory of punctuated equilibrium, for example, does not support a clear division between a chicken and the closest ancestors of that chicken. Both of those factors tend to contribute to the circular nature of the question (causing problems similar to either a hasty generalization or a fallacy of definition). Below are a few different definitions that could be assumed and their logical outcomes.^[6]

• If the egg is not necessarily of any specific type: Then it could be said that the egg came first, because other animals had been laying eggs long before chickens existed, such as the dinosaurs. In biology, egg is used as a general term in this way.
• If only an egg that will hatch into a chicken can be considered a chicken egg: Then a re-consideration of the original question suggests: Some animal other than a chicken laid the first chicken egg which contained the first chicken. In this case the chicken egg came before the chicken. In reality, many scientific theories suggest that this would not have been a simple event. For example, the theory of punctuated equilibrium theorizes that the actual speciation of an organism from its ancestral species is usually the result of many mutations combined with new geographical surroundings, called cladogenesis.
• If only an egg laid by a chicken can be considered a chicken egg: Then a re-consideration of the original question suggests: The first chicken (which hatched from a non-chicken egg) laid the first chicken egg. In this case the chicken came before the chicken egg. Again, this would not necessarily be a straightforward event.

Science and evolution

The Theory of Natural Selection says that species change over time in the process of evolution. Since DNA can be modified only before birth, a mutation must have taken place at conception or within an egg such that an animal similar to a chicken, but not a chicken, laid the first chicken egg.^[7][8] In this light, both the egg and the chicken evolved simultaneously from birds who weren't chickens and didn't lay chicken eggs but gradually became more and more like chickens over time.

However, a mutation in one individual is not normally considered a new species. A speciation event involves the separation of one population from its parent population, so that interbreeding ceases; this is the process whereby domesticated animals are genetically separated from their wild forebears. The whole separated group can then be recognized as a new species.

The modern chicken was believed to have descended from another closely related species of birds, the red junglefowl, but recently discovered genetic evidence suggests that the modern domestic chicken is a hybrid descendant of both the red junglefowl and the grey junglefowl.^[9] Assuming the evidence bears out, a hybrid is a compelling scenario that the chicken-egg came before the chicken.

Theology

Judeo-Christian writings indicate God's creation of birds along with the rest of the universe. The Judeo-Christian story of creation describes God creating birds, and commanding them to multiply, but makes no direct mention of eggs. According to Genesis 1:

¹⁹ And there was evening and there was morning, a fourth day. ²⁰ And God said, Let the waters swarm with swarms of living creatures, and let birds fly above the earth in the open firmament of heaven. ²¹ And God created the great sea-monsters, and every living creature that moveth, wherewith the waters swarmed, after their kind, and every winged bird after its kind: and God saw that it was good. ²² And God blessed them, saying, Be fruitful, and multiply, and fill the waters in the seas, and let birds multiply on the earth.^[10]

In Genesis 1:21 the answer is given as the chicken. In Hindu writings, creation of birds (and other life forms) by God through superhuman beings is stated in Purāṇas^[11] and Dharmaśāstras.^[12]

Examples

There are many real-world examples in which the chicken-or-egg question helps identify the analytical problem:

• A graduate can't get a job because they have no experience, and can't get experience because no one will give them a job. (This is also an example of a Catch-22.)
• Companies find it difficult to introduce new consumer media formats, such as audio recording formats. Most consumers won't buy players for the format until there are many recordings to play on those machines, but record companies won't offer most of their recordings in the new format until many customers have the players. The same scenario applies to video recording formats, video game console systems, and computer systems.
• An actor cannot join the actor's union unless he has played a role in a union film, but a non-union actor cannot get a role in a union film because he isn't in the union.

See also

• Circular cause and consequence
• Catch-22 (logic)
• Evolutionary biology
• On the Origin of Species
• Cosmogony
• Grandfather paradox
• Predestination paradox
• Bootstrapping, a technique in computer programming used to avoid chicken-and-egg scenarios where two programs are mutually needed for compiling or loading each other
• Gödel's incompleteness theorems, mathematical proofs which show the existence of such paradoxes in every consistent logical system.
• Feedback loop

References

External links

• Which came first the chicken or the egg?