Sean M. McDonough declares implausible the idea, on which Howard's hypothesis is based, that κύριος first appeared in the Septuagint only when the Christian era had begun. He says the idea is convincingly contradicted by the testimony both of Philo () and of the New Testament itself. Howard's attribution to Christian copyists the consistent use of κύριος as a designation for God in Philo's writings is countered by Philo's frequent interpretation and even the etymology of the word κύριος. As for the New Testament, even its earliest manuscript fragments have no trace of the use of the Tetragrammaton that Howard hypothesizes and which in some passages of Paul would even be ungrammatical. While some Septuagint manuscripts have forms of the Tetragrammaton, and while some argue that κύριος was not in the original Septuagint, it is certain that, when the New Testament was written, some manuscripts did have κύριος.