Quaeritur: I'm reading the first few questions of the IIIa Pars, and it seems many of these questions are on hypothetical scenarios having to do with whether God could have assumed human nature in this or that way, other than the way it actually happened.
For example: in IIIa, q. 1, q. 3, he asks whether God could have become man had Adam not sinned; in aa. 5 and 6 he asks whether it would have been better for Him to become Incarnate at the beginning or at the end of the world. And then in q. 3 he asks more hypothetical questions, such as whether a different Divine Person, or multiple Divine Persons could have assumed human nature; and whether the Word could have assumed many individual human natures. Also in q. 4 he asks whether the Word could assume a different nature besides human nature, whether he could have assumed a human person, or a man, or an abstract human nature, or all individual human natures, or a different human nature not related to Adam.
It seems that many of these questions ask the basic idea of whether God can perform this or that, which in light of the attribute of omnipotence, the majority of the time, the answer is "yes" to anything that God desires. There are only a few times when the answer is negative, and it seems these limited cases boil down to the whole question of: "Can God build a rock that is too heavy for Him to lift?"
So given that the answer is nearly always affirmative--unless it involves contradiction that is--it almost seems like these questions are a bit repetitive. They are highly speculative and maybe not so important... or dare I say, “useless,” a waste of time?
Alas, my modern sensibilities are not yet perfectly attuned to St. Thomas’ wisdom, despite decades of study, and I cannot quite see the point of going into so much detail about what God could have done but didn't.
Why is St. Thomas so eager in this futile search, concerning which nothing for certain can ever be known, other than that God could have done anything He wanted except contradictions? What are your thoughts?
Respondeo: Excellent question, and thank you for your honesty. I agree that sometimes it is not evident why St. Thomas considers it important to consider a given question, especially when it involves a hypothetical, counterfactual scenario such as whether God could have become incarnate otherwise than the way He actually did.
But I'd be more careful with questions regarding Divine Omnipotence. I don't think questions about whether God can do x or y are so easily answered in the affirmative simply because of God's omnipotence. As you point out, there are meaningful questions about God's power which in fact have negative answers; but they do not always boil down to trivial contradictions.
Questions about whether God can or cannot do x or y ultimately do boil down to whether x or y involve a contradiction in themselves, a mutual "repugnance" of terms; but that repugnance of terms is not always self-evident, and often we can learn a lot about the terms themselves that involve a contradiction. The "rock that God made too heavy for Him to lift" is surely an example of something that involves a contradiction in itself. It is also a somewhat silly and trivial example at that. But there are more serious, meaningful, and educational examples of things that God in His divine omnipotence cannot do, because they involve a contradiction in terms, such as the following: God having potency, being affected by a creature (undergoing passion), God learning, changing His Mind, ceasing to be God, ceasing to be omnipotent or generally losing any of His attributes, lying or sinning in general, creating a creature that can create, etc.
Thus, the answer to questions regarding whether a Divine Person can assume this or that nature, many natures, two Persons in the same nature, etc., do not automatically default to affirmative answers because of God's omnipotence. In fact, if these hypothetical acts of Divine Persons assuming other natures somehow affected the Divine Nature itself, changing it in any way, they would be impossible for God to do. St. Thomas has to show first that these acts do not affect the Divine Nature before he can conclude that they would be possible for God to do them. Conversely, if the question were whether the Divine Nature itself could become human, thereby ceasing to be divine (or eternal, or simple, or immutable, etc.), the answer would have to be: "No." Clearly, then, not every question about God's power---even outside of the heavy rock example---is simply to be answered in the affirmative owing to Divine Omnipotence.
And obviously St. Thomas himself didn’t think these hypothetical questions were useless, given that the Summa was written precisely in order to remedy a pedagogical problem in his time, the growing number of theological works written for beginners which engaged in a “multiplication of useless questions, articles, and arguments.” He tells us in the prologue to the work, that:
“We have considered that students in this doctrine have not seldom been hampered by what they have found written by other authors, partly on account of the multiplication of useless questions, articles, and arguments.... Endeavouring to avoid these and other like faults, we shall try, by God's help, to set forth whatever is included in this sacred doctrine as briefly and clearly as the matter itself may allow.”
St. Thomas has parsimony and economy of questions in mind when he writes the Summa. He must, therefore, think that these hypothetical questions regarding what God could have assumed, or how God could have become man, must be significant for our understanding of Christ.
So as faithful students of St. Thomas, we must refuse to fall into the temptation of thinking of these questions as though they were mere useless speculations, as though St. Thomas were engaging in mere theorizing-for-the-sake-of-theorizing.
In fact, given our 'modern sensibilities, as you say, it shouldn’t surprise us that he does this, especially if we reflect on our own modern modes of thought. Especially in analytical philosophy and in ethics within the Anglo-American tradition we do much of the same types of thought experiments, such as our ‘black boxes’, our ‘Chinese rooms’, our ‘Schrödringer’s cats’, our ‘trolley problems’, our ‘veils of ignorance’ and our ‘lifeboat ethics’. These thought experiments posit scenarios which are abstract, overly simplistic, unrealistic, and even impossible, and yet we use them as illustrations that help us answer important questions. They filter out the irrelevant details of a question, and isolate what is at stake in the problem; they enable us to encounter the limits of what can and cannot happen in reality, but without the distraction of other confusing elements that reality usually comes with.
In the same way, St. Thomas is here illustrating for us through his own ‘thought experiments’, as it were, the true meaning of the Incarnation: by showing us what can and cannot happen, we are gradually being led by this wise Doctor to understand more precisely what a Divine Person is, what an assumed nature is, what the term of the assumption is, the infinite extent of the divine power as it is exercised in the Incarnation, the limits of creatures’ passive potency, the purpose of the Incarnation, and of course the limits of our language.