reasoning
n. uncountable C1 Advanced Oxford US //ˈɹizənɪŋ// UK //ɹˈiːzənɪŋ// rea·son·ing
n. the process of thinking about something in a logical way to reach a conclusion. You use it to explain the 'why' behind your decisions or beliefs.
n. the process of using logical thought to form conclusions, inferences, or judgements. Often used to describe the underlying logic of an argument or decision.
I do not understand the reasoning behind your decision.
The committee asked the architect to explain the reasoning for choosing such expensive materials for the new library.
While the conclusion of the study was popular, critics pointed out that the underlying reasoning was based on a series of unproven assumptions about human behaviour.
Usage
Commonly followed by the prepositions 'behind' or 'for' when explaining a specific choice.