- another term for raison d'état.
Middle English: from Old French reisun (noun), raisoner (verb), from a variant of Latin ratio(n-), from the verb reri 'consider'
1 The construction the reason why ... has been objected to on the grounds that the subordinate clause should express a statement, using a that-clause, not imply a question with a why-clause: the reason (that) I decided not to phone, rather than the reason why I decided not to phone. The reason why has been called a redundancy to be avoided, but it is a mild one, and idiomatic. 2 An objection is also made to the construction the reason ... is because, as in the reason I didn’t phone is because my mother has been ill. The objection is made on the grounds that either “because” or “the reason” is redundant; it is better to use the word that instead (the reason I didn’t phone is that ...) or rephrase altogether (I didn’t phone because ...).Nevertheless, both the above usages are well established and, although they may be inelegant, they are generally accepted in standard English.