What’s the difference between a physical and metaphysical account?

It’s easy to object that someone is really making a metaphysical claim when they claim to be making a scientific one – but what exactly does this mean?

Minimally, one might mean that someone is making a claim that is not experimentally verifiable or reducible to physical laws. To leave it at this, however, tells us nothing about metaphysics, since the pure negation of verifiability tells us nothing positive. Informing me that a doctrine contains non-verifiable statements tells me about as much as informing me that a box contains several objects that are not snow. What do I know about the contents of either after hearing this?

One might say that metaphysics studies being as such while all other sciences treat of being under some restriction. This explanation has some value – scientific journals after all don’t publish many studies on being or existence, and no one seems to bother looking for “laws of being” – and so there certainly seems to be something to distinguishing science and metaphysics in this way. The difficulty is that this does not seem to be a way in which anyone confuses metaphysics and science.

The challenge thus becomes how to account for metaphysics as non-empirical in a way that ties it somehow to being as such. We can do this by considering the lights of judgment,  that is, the various lights that constitute the evidence of diverse sciences.

All knowledge begins in exterior sensation and involves the intellect and interior senses, but each of these three is a distinct mode in our single act of knowing, and so we can judge a single thing known according to three diverse modes in our single cognitive act. Said another way, just because our experience arises from sense it does not follow that we must judge that experience in light of what we know from the exterior senses as such, since this is not the only light in virtue of which we can consider the experience.

As St. Thomas explains it, natural science (which we call just “science”) is that category of experience that arises from exterior sense and is judged by the light of the data furnished by the exterior senses themselves; metaphysics is the category of experience that arises from the exterior sense and is judged by the light of the intellect. By empirical we mean that experience is to be judged according to the way they are known by the exterior senses as such. Said another way, in order for something to count as evidence in natural science, it has to be given in experience according to the way experience is in the exterior senses. All evidence requires some light under which a thing appears as evidence, and that light in natural science is the exterior senses. Metaphysical evidence is not manifested by the same light, and so is not empirical, since it judges experience as known by the intellect. And because what is first known by the intellect is being, ti follows that metaphysics is non-empirical and about being for one and the same reason, namely, the proper object of the intellect as intellect.

Understanding the diverse lights of judgment or evidence helps us divide diverse concepts that are easy to muddle if we are not careful:

1.) Species. For the metaphysician, a species is the proper intelligible nature of some reality. This intelligible nature is discerned according to the way it is present in the intellect: that is, as first known generally and then more distinctly by way of precision in the general concept. Metaphysics is, on the consideration of species, very close to logic and makes much use of it, but the two remain distinct since metaphysics never takes experience as known (or being as known) as the subject that it studies. Metaphysics remains about being as being, logic about the more restricted notion of being as known. Natural science, on the other hand, is not primarily concerned with species according to their intelligible structure, but in the way in which they can be given in the exterior senses as such. This makes species principally a multiplicity of individuals taken as principally multiple. Species thus means principally a population or multitude of traits.

2.) Causes. In sensation, a cause presupposes some actual thing that it must act upon, and thus a cause must always depend on some other in order to exercise its causal power. But as present in the intellect, cause is formally distinguished from dependence, since dependence is a way of being an effect of another. Thus, creation (that is, causality that presupposes no subject) is a possibility in metaphysics whereas it is not a possibility for natural science.

3.) Motion. In the way it is given to sense, motion is the most knowable and obvious of things. The natural scientist thus takes motion as a primarily known reality that is perfectly evident in itself. When judged in light of the intellect, however, motion is the least known and even least knowable of things. Motion is a tremendous problem for the one who judges experience by intellect, for the first thing known by the intellect is being whereas motion as such is becoming, which is a the same time essentially related to being and yet opposed to it. Motion will eventually require the metaphysician to make a division within reality as such into more primordial concepts; whereas the physicist resolves all other realities to the given reality of motion.

4.) Quantity. The natural scientist resolves all thing to experience as given in the exterior senses, but the primary and foundational reality in this order is quantity. All natural science, therefore, progresses by becoming more quantitative.  Metaphysics, on the other hand, progresses more by its transcendence of the quantitative order, by progressing towards spiritual reality.

Besides these four, there are all the differences that were treated of in the body of the post: there are distict senses of “evidence”, “judgment”, “experience”, “known by sensation”, etc.

And I left off the whole universe of things that provide their evidence from the light of the interior senses – that is, mathematical reality. Mathematicians don’t wade into the dispute about science and metaphysics, though they could. But there really is a whole universe of mathematical reality out there – even though the mathematicians always seem to want to keep it to themselves.


  1. jayman777 said,

    January 29, 2011 at 11:54 am

    You state that metaphysics is judged by the intellect. How does this play out in practice? For example, how can I rationally determine whether formal causes exist or not?

  2. January 29, 2011 at 12:18 pm

    So the four examples I give don’t give you a sense of how this “plays out in practice”? I used for different examples because the way it “plays out” is not always the same.

    If your question is simply about form, the word does not always mean the same thing. The first sense of the term is just “shape”, but presumably your question isn’t whether shapes exist. I don’t think your question is whether shapes can be causes either, since the shape of the ball is one cause of why we can call it a ball.

    The idea of shape as a cause extends easily to position being a cause, for example, the cause of my lap is my sitting down. Likewise, the cause of something being a threshold is placing it across the bottom of a door, and a cause of a word being “cat” and not “act” is the position of the letters that make it up. A car is made up by this sort of positioning too.

    The idea of position can extend to mean the right mixture of various elements. Bread and wine are certain wholes made up by the mixture of the parts together, as are most foods. Here again, mixing to make a whole is a certain cause of the resulting whole.

  3. jayman777 said,

    January 29, 2011 at 1:05 pm

    James, sorry if I am a little unclear. Let me state up front that I find Thomism intriguing but I’m not sure that it’s true in its entirety. What I’m ultimately trying to determine is whether it is true and how I can rationally compare it to other metaphysical theories. I realize this is a big question so if you have any links or books that you think will answer my question feel free to provide them.

    So the four examples I give don’t give you a sense of how this “plays out in practice”?

    Examples (1) and (4) made sense to me. Example (2) makes some sense but I would follow up by asking whether “creation” is actually possible or merely conceivable. Regarding (3) I am guessing you believe the metaphysician has to divide reality into at least actuality, potentiality, and the four causes of Thomism. Many people seem to doubt the existence of formal and final causes so how could one go about defending their existence to the skeptic? Is it merely that the world is more intelligible if they are presupposed than if they are not?

    If your question is simply about form, the word does not always mean the same thing.

    That might be part of my problem. Your examples of formal causation were clear. However, I am still unclear on how one can say forms exist in entities that do not have material causes (e.g., the disembodied human mind, angels, God).

  4. G. Kyle Essary said,

    January 31, 2011 at 6:07 am

    You may be interested in reading one of two books by Ed Feser. The first is called “The Last Superstition.” Although it is aimed at debunking the New Atheists (and it does this in an exceptional way), it also provides a good introduction to general Thomistic thought and provides plenty of examples for each of the causes. He also wrote a book titled “Aquinas” that gives the best, simple introduction to Aquinas that I’ve read and does much of the same as the other book, but follows it up by showing how this thinking applies to other areas beyond his discussion of the four causes.

  5. jayman777 said,

    January 31, 2011 at 3:29 pm

    G. Kyle Essary, I have read both books. I’m not sure either book really argues for why you should be a Thomist. If you disagree, feel free to suggest page numbers from either book for me to re-read.

  6. G. Kyle Essary said,

    January 31, 2011 at 7:38 pm

    I’m glad you have read them both. No, neither argue “why you should be a Thomist,” but both make a good case for Thomism and show how it works in the real world. I’m not sure what “The Case for Thomas” would actually look like…do you have any ideas for what it might include?

    I can think of some more general introductions like “The One and the Many” by W. Norris Clarke, and I’ve heard McInerny’s introduction to Thomas is good. For more in-depth arguments for “why you should” hold the arguments, I can only think of some by specialty (such as Wolfgang Smith’s Quantum Enigma which argues against hidden Cartesian dualisms in modern science before suggesting a Thomistic stance that makes better sense of the data).

    I’m pretty new to Thomism having only read fifteen books or so in this philosophy (outside of general natural law books). I would guess that James could offer more insight if he were to chime in.

    • February 1, 2011 at 12:07 pm

      I give lots of answers to the question “what book should I read to understand St. Thomas”, but I’m starting to think that the better answer is not to hold up books but groups or institutions. I don’t say that to be contrarian, or because I think it is a real possibility for everyone, but to express where I think our goals should be- not so much to read books, but to read St. Thomas himself with friends in a spirit of discipleship.

      • G. Kyle Essary said,

        February 1, 2011 at 4:17 pm

        I’m interested in what you mean by institutions. Outside of the church do you have something else in mind?

      • February 1, 2011 at 6:02 pm

        At the most mimimal level, there is a blog community: people with overlapping interests banging ideas off of each other, who are empowered by the awareness that what they say will be out there for people to see. A reading community or book club is a minimal institution too.

        The real goal (for thomists anyway), however, is a system of education that starts young with Euclid and logic and Latin and composition, that has them memorize several thousand lines of the best poetry, that teaches kids to read music and sing polyphony, run long distances and lift weights; (and that either skips Algebra and science, or finds some way to teach them in a fitting way) that has students reading Aristotle in light doses by fourteen and very heavily by the age of twenty, that culminates to St. Thomas in the twenties and early thirties, and then lets whoever wants to keep going in this study the tradition that came after him.

        The institution would be far more than one school; the goal is a whole well-established chain of schools… many elementary schools and high schools with low tuition and broad access and high fail-out rates – colleges and grad schools that only a small portion fo the students feel the need to go on to (many more get married and live productive lives after high school)…

        Don’t worry, I’ll wake up any minute now…

  7. Sean Schniederjan said,

    February 1, 2011 at 11:12 am

    “natural science (which we call just “science”) is that category of experience that arises from exterior sense and is judged by the light of the data furnished by the exterior senses themselves”

    I see this in a way and don’t in another. “Motion exists” is a judgment of sensed data. But when we turn to define motion, we have to use metaphysical concepts (act and potency) to make what we sense intelligible. So there aren’t we judging by the light of the intellect (act is that-for-the-sake-of-which a thing is, potency is ordered to act)?

  8. February 1, 2011 at 11:56 am

    Right. That would bring up the next point. Natural science can make use of concepts that, in themselves, are proper to metaphysics – just as it can make use of concepts that are proper to mathematics (this seems to just be a consequence of all of these things being a part of a single cognitive experience). But these have to be subordinated to the mode of verification proper to natural science. The doctrine of subordination of sciences is itself a very big thing – and no one has quite worked out all the possible connections of subordination that can be drawn.

  9. jayman777 said,

    February 1, 2011 at 3:46 pm

    G. Kyle Essary:

    I’m not sure what “The Case for Thomas” would actually look like…do you have any ideas for what it might include?

    Only in a general way, which is why I asked the question. I think it would include:

    (1) An explanation for how Thomas and his predecessors came up with their ideas. To take your example, how did Thomas arrive at his position on the mind?

    (2) Demonstrate that Thomism makes the world more intelligible than other metaphysical positions. For example, why is Thomas’ position on the mind better than Decartes’?

    (3) Criticism of alternative ideas and answers to objections to Thomism.

    (4) Reasons for believing that Thomism is true and not merely a useful fiction.

    One book probably can’t cover everything. But I imagine there could be books about ontology, mind, morality, etc.

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