What We Can Know, and How We Can Know It

According to Thomas Aquinas, we can know things in three ways:

  • Directly, as we know the things we see around us.
  • Indirectly, by reasoning from the things we see around us.
  • By revelation from God.

The first category—the things we know by direct experience, as I know the keyboard on which I’m typing and the desk it sits on—would go without saying if it weren’t for the persistent influence of Descartes’ methodological doubt and the absurdities of those who followed after him. As for me and Thomas, we accept objective reality as a given. (Yadda yadda yadda, brain in a jar, yadda yadda yadda: I’m not buying it.)

Second, we can learn many things by reflecting on the things we know by direct experience, and by reasoning about those things.

Men looking through microscope Scientific knowledge, properly understood, is a combination of these first two categories. It is always based on observation of things as they are, possibly with the help of complex instruments such as microscopes and supercolliders; and it is always based on reasoned abstraction from those observations. Newton did not observe that Force = mass times acceleration; he observed objects in motion, abstracted from those motions the notions of force, mass, and acceleration, hypothesized that the equation F = ma described the relationship between them, and found that in the examples he saw around him that F = ma was a good fit to the data. Similarly, Ptolemy was trying to predict the motions of the heavenly bodies. He proposed a model, based on observations taken with the naked eye, and found that it did a good job of predicting them—such a good job that it held up for over a thousand years, until better observations made with telescopes were available. (Michael Flynn has told the story of the Great Ptolemaic Smackdown in painstaking but fascinating detail; highly recommended.)

But though Thomas would certainly have supported the scientific method, as it later came to be understood (his master, St. Albert the Great, was the greatest scientific observer of his day), he went beyond that. In addition discovering the proximate causes of the events and phenomena in front of us, he believed (with Aristotle) that there were ultimate principles that could be discovered by applying logic to fundamental truths and observations of nature. One of these ultimate principles, according to Thomas, is the existence of God, and a handful of facts about Him. These, he thought, could be objectively and rigorously proved.

I am not attempting to prove this here, mind you, as it’s a lengthy chain of reasoning, and though I’ve followed it I’m not at all confident of my ability to present it accurately. I’ll simply note that Aquinas’ famous “five ways”, found in his Summa Theologiae, are proof sketches, rather than full-fledged proofs, and depend on a shared philosophical (not theological) understanding that derives from Aristotle’s Physics and Metaphysics. I may have some words to say about those at a later date.

Still, Aquinas’ proofs about God, what is called his “natural theology”, do not go very far, and are more about what we cannot say about God than what we can. To go farther we need revelation. God’s revelation to us, through Abraham, Isaac, and Jacob, through Moses and David and Solomon, and ultimately through Christ, shows us a God, creator of all, who wishes to make Himself known to us.

Aquinas did not hold that we could prove the truths of “revealed theology” as we could prove the truths of philosophy and natural theology. But one of the things Aquinas shows in the Summa is that God is not simply a speaker of truth, but Truth itself. God is not, therefore, a liar: everything He does is consistent with everything else. As He is the creator of the natural world, and the author of revelation, then, these two things cannot ultimately be in conflict. (This is why the Church accepts the fossil record and doesn’t generally support Young Earth creationism—if the earth is young, the fossil record would seem to be a kind of lie.) Thus, in the Summa Aquinas operates in two distinct modes:

  • He proves what he can prove (natural theology)
  • He refutes objections to proposition of revealed theology

In short, when I tell you that Christ is the Son of God, the incarnation of the Second Person of the Trinity, I cannot prove to you that this is the case, either on scientific terms or by the kind of rigorous philosophical demonstration that Thomas favored. What I can (in principle) show is that it is not logically inconsistent with what we can know without revelation. (I say “in principle” because though I’ve been studying up on these things, as a philosopher/theologian I remain a pretty good software engineer.)

And that brings us to faith, which is not a blind acceptance of logical propositions, but trust in a person, Jesus Christ. You don’t need to know (or be able to articulate) everything about a person to know that they are faithful, that is, trustworthy. And because they are trustworthy, you can take what they say “on faith”. What Catholics mean by the God-given gift of Faith is this ability to trust in Jesus Christ.

I cannot argue you into this kind of faith, no matter how hard I try. All I can do is to do my best to introduce you to Jesus Christ himself; and ultimately, you have to ask Him to introduce Himself. Marshall McLuhan did this, as Julie Davis related recently. He prayed, “Lord, please send me a sign.”

He asked sincerely, and God answered.

photo credit: El Bibliomata via photopin cc

About willduquette
  • michelangelo3

    The content of public divine revelation is “knowledge” for God who reveals it, and for those biblical figures who directly experienced it. But it is not knowledge for us, who can apprehend its truth only by trusting those secondary authorities who propose it with divine authority.

    • http://acatholicviewoftheworld.wordpress.com/ Roki

      The word “knowledge” has a variety of definitions.

      In the sense of “certain, complete, comprehensive, direct understanding”, then yes, the content of faith is not “knowledge” for us.

      However, in the sense of “information understood” or “awareness of the truth of something”, the content of faith can be called “knowledge.”

  • LFCasey

    Bill Nye and Ken Ham had a recent debate on young Earth vs. science, but unfortunately Ken forgot the 3rd way, science and God together! What a concept.

  • Alex Symczak

    I disagree, faith is the blind acceptance of logical propositions. Let’s start with your definition, “trust in a person, Jesus Christ.” How did we get to this point? Well, you have to assume that he exists, and likely you assume that he exists in a such a state as the Bible describes. Then you judge him as trustworthy, probably using material from the Bible.

    Do you see the problem? You have to blindly accept some big things to get to trusting in your God. Dropping any of these Premises leads to nonsense.

    Also, you can’t argue me into this kind of faith? It relies purely on personal revelation? Then you have no reason to think you’re following the right religion. Your justification cannot distinguish between You, or a protestant, or a Hindu, or a Muslim, or a Pagan. What makes you so special, that God gave you the correct revelation? Or are all others just lying?

    Finally, I have to ask your god to introduce himself? Well, that would require me to assume that he exists. And since I’m guessing that the purpose of this exercise is to gain good reason to believe he exists, this argument becomes Circular.

    • Will Duquette

      Alex, I’ve made a list of questions I plan to answer at some point in blog posts, including how I personally came to believe; the other questions you raise are among them. Point is, next time you can simply comment, “Will, I’d like to raise my usual questions; you haven’t answered them yet.” :-)

      What I will say here is simply that I came to trust God and accept his existence through personal experience; but that what I have learned intellectually since then has bolstered my belief, not cast it into doubt. But I’ll have to write more about this later.

      As for introductions: if you wonder whether someone is home, it’s reasonable to knock on the door and see if anyone answers.

    • Will Duquette

      Oh, and as for faith “being the blind acceptance of logical propositions”—that’s not at all what the Catholic Church means by the word “faith”. If you insist on interpreting my terms with your definitions, we won’t get anywhere.

      • Alex Symczak

        Very well, we can use your definition, but my main point stands. I don’t think you have good reason for your belief. I await your future posts on this matter. It seems as though personal revelation is an important core of your argument, so I would suggest trying to show how this is a good reason for belief.

        In regard to your final point: “if you wonder whether someone is home, it’s reasonable to knock on the door and see if anyone answers.” I have a problem with this analogy. Yes, it is reasonable to knock to see if someone is home, but why is that? It is because I know that humans build houses and live in them, and that knocking on the door is a good way to get their attention and bring them to the door if they are home. I’m assuming that when you say I should “knock on the door” that means I should get on my knees and start speaking into the air. I don’t have reason to believe that there are beings living out there somewhere (In the sky? In another dimension? Depends on who you talk too, and it doesn’t matter anyway) and that speaking into the air is a good way to get their attention and see if they are there. I might as well say you should play a trumpet for mushrooms to see if Smurfs are there. That is not reasonable.