rationale
noun [ C or U ] formal uk/ˌræʃ.əˈnɑːl/ us/ˌræʃ.əˈnæl/
根本原因；基本原理
the reasons or intentions that cause a particular set of beliefs or actions
I don't understand the rationale for these restrictions. 我无法理解这些限制。
He tried to explain the scientific rationale behind his work. 他尝试解释他工作背后的科学原理。