(also called Principle of Reason).— The principle according to which whatever exists must have a reason for its existence, this reason being either intrinsic or extrinsic to the thing which exists. Sometimes, to avoid rationalist connotations, this principle is referred to as the principium rationis essendi or “the principle of the reason for being,” so as to emphasize that this principle is concerned with the various causal dependencies of beings in their very reality and not only in their cognitive conception.