The phrase "primary rationale" refers to the main or most important reason or justification for something. It is the primary factor that is used to support or explain a decision, action, or belief. Full definition
The two primary rationales behind granting citizenship are jus soli and jus sanguinis: by right of land and by blood. (rocketlawyer.com)
Fundstrat cites regulatory risks excessively priced into platform tokens as the primary rationale behind creating the new benchmarks. (thewealthadvisor.com)
When you put all this together, the primary rationale for all of these changes (according to the Fed) reflects general expectations for weak global growth as well as concerns about financial - market volatility that came to a head the first couple of months of the year but continue to persist. (us.beyondbullsandbears.com)