The Greek expression ho on used by Philo (strictly speaking) only depicts "an aspect of [God's] potencies" since God reputedly does not possess any distinguishing self-designation: "God indeed needs no name; yet, though He needed it not, He nevertheless vouchsafed to give to humankind a name of Himself suited to them, that so men might be able to take refuge in prayers and supplications and not be deprived of comforting hopes." Philo effectively makes a distinction of reason (distinctio rationis) between names of substance (nomina substantiae) and names of mercy (nomina misericordiae) when he suggests a proximate referring term for YHWH. He asserts that there exist both names descriptive of God’s substance and names vouchsafed to humankind founded on God's compassionate mercy. However, immanently, Philo holds that God is anonymous. One encounters a similar notion in Cratylus 400-401.
The Philonic doctrine of innominability appears perplexing in view of the emphasis on a nomen proprium for God in the Tanakh (Exodus 3:15; Isaiah 42:8; Zechariah 14:9). The Tetragrammaton (YHWH) occurs nearly 7,000 times in the canonical Hebrew-Aramaic Scriptures. One consequently wonders whether Philo either knew Hebrew or was personally acquainted with the quadrilateral name of God that one encounters frequently in the Jewish Scriptures. It is highly probable that he was neither conversant with Hebrew nor the proper name of God (Shem ha-meforash). A number of related factors certainly suggest that Philo lacked adequate proficiency in a Semitic language: his educational background, Sitz-im-Leben and philosophico-theological treatises all indicate that the Alexandrian did not have a suitable grasp of Hebrew.
First, it is evident that Philo had a traditional Hellenic education. He possessed a well-rounded knowledge of Homer, Demosthenes, Greek poetry as well as Platonic and Stoic philosophy. Although Philo had an "excellent education" in matters Jewish and Greek, Dillon thinks that he was not proficient with Hebrew as evidenced by his vague allusions to the Tetragrammaton and his mistaken etymologies for Semitic names. Philo "frequently" misconstrues Semitic etymologies, ostensibly being dependent on the Greek Septuagint (LXX) version of the Bible. The extant data would appear to indicate that he scarcely knew any Hebrew and possibly did not even have first-hand acquaintance with the four Hebrew letters that constitute God's proper name (YHWH).
Second, Koine Greek was the universal language (Weltsprache) of first century Jews in Alexandria. This socio-historical datum is one factor that motivates David Runia to conclude: "That Philo himself had no knowledge of Hebrew is almost certain. It was therefore an event of enormous importance for the Jewish community in Alexandria that the Hebrew Bible was translated into Greek." Hence, Philo's lack of familiarity with Hebrew may partially explain his innominability doctrine. On the other hand, his theoretical assumptions pertaining to ultimate reality and categorically shaped this belief as well.