rationale

/ˌræʃəˈnæl/

ra·tion·ale

BrE /ˌræʃəˈnɑːl/

NAmE /ˌræʃəˈnæl/

~ (behind/for/of sth)

(formal)

the principles or reasons which explain a particular decision, course of action, belief, etc.

SYN reason

What is the rationale behind these new exams?