Latin, “other things equal”
An important assumption in economics and developing economic models, suggesting that all other variables are assumed to be constant or unchanging. Useful especially in building hypotheses, economic theories or models with two more variables; we assume that variables we don’t study remain unchanged.
Our reasoning is that if all or more variables change at the same time, we have no way of knowing what effect each of them individually has on changing consumer behaviour.
We may observe that in the real world, all variables are changing at the same time, and ceteris paribus tells us nothing about what is happening in the real world — economists use it to isolate and study the effects of one variable at a time.