Sadly, even here, or perhaps mainly here, I shout at Thomas. Take ST 1, 1, 1:
“Hence it was necessary for the salvation of man that certain truths which exceed human reason should be made known to him by divine revelation.”
That’s a plain admission that reason alone is not up to the job.
Merely because reason cannot attain “certain truths” does not entail all truths are beyond reasoning. So, a conclusion that reason “is not up to the job” is a hasty one, at best.
Without specifying which truths are problematic for Thomas, you have no reason to “shout at him.” There is no “plain admission” involved. Thomas is quite clear about truth claims that can be made and those which are beyond the capacity of reason.
Unless you specify which claims, precisely, are problematic for Thomas, you are doing what I once saw a delusional man do, i.e., wandering the inner core of a city shouting incoherently at no one in particular concerning some delusional fantasy that preoccupied his mind.
There is no argument that can be found in Thomas’ admission that merely because some truths are beyond reason, all truths must be. If you want to shout down Thomas on the grounds that because some truths are beyond reason, all truths must be, I see no difference between you and the delusional man in my story.
“Even as regards those truths about God which human reason could have discovered, it was necessary that man should be taught by a divine revelation; because the truth about God such as reason could discover, would only be known by a few, and that after a long time, and with the admixture of many errors.”
So it’s possible to construct some reasoning around revelation, which is fine, that’s just saying revelation is not unreasonable. But he goes on to claim that after a long time and with many errors it would be possible to construct the reasoning in the absence of revelation, but there’s no way he can possibly know that.
And since we have revelation, we don’t need to construct the reasoning anyway, so he just put himself out of a job even before he gets started.
Which is an admirable trait in any philosopher.
Again, you are demonstrating a less than “admirable” trait by invoking wildly inconsistent reasoning.
Even if truths are revealed, why would that render reasoning about them unnecessary? It seems to me “knowing that” something is true (gravity, for example) is quite a different matter from “knowing why.” What you seem to be saying here is that once we know that the law of gravity is true it renders all other “knowledge” about gravity superfluous and unnecessary.
Regarding revelation, we may come to know by revelation that grace is operative in our lives, but why it is so and why it is even necessary may be quite discoverable by a process of reasoning from the human condition, once we know “that” it is.
Revelation may provide the appropriate and important conclusions for chains of reasoning that may never have even been considered by unaided human thought, but once the conclusion is “seen” or “known” by revelation, how it might function as the logical conclusion from known premises then becomes clear. Thinking “outside” the box is a clear example of beginning with a point outside one’s realm of possibilities and then finding the path of thinking that gets you there.
If I find a map that tells me that Destination A lies 300 km northwest of my current location, I may never have thought to look for Destination A or spent a lifetime stumbling around with no clear view or idea of where I was going because I had no knowledge that Destination A even existed. Revelation can operate to overcome the “…long time and … many errors it would … [require] to construct the reasoning in the absence of revelation…” It is the certainty of the revelation that could be very helpful in guiding reason in the right direction, not as you say to, “put philosophers out of a job.”