chicken-and-egg

[chik-uh n-uh n-eg, -uh nd-]

adjective

of, relating to, or being a dilemma of which of two things came first or of which is the cause and which the effect: a chicken-and-egg question of whether matter or energy is the basis of the universe.

Also chick·en-or-egg

[chik-uh n-er-eg] /ˈtʃɪk ən ərˈɛg/.

Origin of chicken-and-egg

First recorded in 1955–60

“It is a chicken-and-egg thing,” says one senior Western diplomat in Doha.
Crossing the Rubicon in Syria
Christopher Dickey
November 11, 2012