Dale Tuggy said:
We can ask here, of whom is Isaiah speaking? Who is this YHWH? We might well think it is the Father, since the NT plainly presupposes that the Father of Jesus and the one true God Yahweh are one and the same. Of course then anyone else, would not be the one true God.
But if I understand him, Steve thinks Isaiah there speaks of the one perfect Self, who later, we learn, is the Trinity. Isaiah of course doesn’t say anything about whether or not this perfect Self contains or is somehow composed of other selves.
I already addressed this question from another angle:
But now I’m going to revisit the question from a different angle. In the orthodox doctrine of inspiration, we normally distinguish between the primary (divine) and secondary (human) authorship of Scripture. The primary/secondary distinction is a type of cause/effect relation.
This, in turn, can generate a potential distinction between the divine viewpoint and the human viewpoint. The primary author is both infallible and omniscient whereas the human author is infallible, but not omniscient. There is what the human author consciously intended, and there is what God intended the human author to mean. These are mutually consistent, but not conterminous.
This can also give rise to other potential distinctions. Considering original intent, we might distinguish between subjective intent and the objective referent. As well as between a singular sense and multiple referents.
This is sometimes distinguished by asking if OT prophets “spoke better than they knew.” And, in principle, the same distinction applies to NT prophecy.
One reason we draw these distinctions is to avoid anachronistic interpretations. To avoid making writers mean more than they were in a position to know or convey.
However, in Isa 40-48, the distinction between primary and secondary authorship frequently breaks down. That’s because, in these chapters, God is often the speaker. Isaiah isn’t simply speaking on God’s behalf. Isaiah isn’t simply the second-person narrator.
Rather, God is speaking in his own voice. Isaiah is God’s mouthpiece, quoting God–in the first person. Direct, rather than indirect, divine discourse.
But in that case, the viewpoint is omniscient. We don’t have to draw the customary distinctions in progressive revelation. Between the past perspective of the speaker and subsequent revelation or future fulfillments.
For if God is the speaker, then whatever is true at anytime is present in God’s mind. It’s not anachronistic to take later revelation into account.
If, according to the NT, the Trinity is God, then we can properly gloss or paraphrase the monotheistic statements in Isaiah thusly:
“For I am the Trinity, and there is no other;
I am the Trinity, and there is none like me.”
“For I am the Trinity,
besides me there is no other Trinity.”
The unicity of God would mean there is no other Trinity. There is only one Trinity.
And if we wanted to, we could apply Leibniz’s law to that characterization.
Keep in mind, too, that the uniqueness of God in Isaiah is not contingent on what divine names are used. Isaiah frequently uses “Yahweh” because, through Pentateuchal usage, that had already become a brand name for the true God. So it makes sense to use a name that already has distinctively divine connotations.
But in principle, Isaiah could use a different, or novel, designation for God. For Isaiah demarcates the one true God, not so much by the choice of divine names, but by the unique actions and the unique attributes which Isaiah ascribes to God–in contrast to the pagan pantheon.
After all, Isaiah also uses “Elohim,” but that name does not, of itself, single out the one true God. That’s a question of context, and not merely the occurrence of the word “Elohim.”
