Aristotelian-Thomistic Philosophy and Scientific Evidence

This is what I want to know. On what demonstrable basis does AT make all these scientific claims? Where’s the actual evidence for all the claims about “prime matter”, and “accidents”, and “incidents”, and “substance”, and “form”, and “properties”, and God’s mysterious role in chemistry and physics?

What experiments do AT theorists make to test these claims? How is AT science actually carried out? Where are all the AT scientific research institutes making groundbreaking discoveries with AT science?

These are not scientific claims, and were never meant to be. Have you been following the discussion?

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7 posts were split to a new topic: Lutheran Metaphysics

Yes, I have been following the discussion, and read every post.

This doesn’t address what I wrote. I didn’t talk about competition with the scientific method. These are certainly “meta-interpretations of scientific facts”. These are scientific claims.

It looks to me like scientific claims are being made, then when evidence is requested the response is “these are not scientific claims”.

Having said that, regardless of whether scientific claims are being made, my questions still stand. On what demonstrable basis does AT make all these claims? Where’s the actual evidence for all the claims about “prime matter”, and “accidents”, and “incidents”, and “substance”, and “form”, and “properties”, and God’s mysterious role in chemistry and physics? How is AT any different to astrology?

I don’t think that there’s a way you can evade metaphysics, just like you can’t evade having a philosophy of science (or philosophy of ethics, mind, etc.). Metaphysics (as we use the word today) is a branch of philosophy dealing with the study of the fundamental nature of existence, being, and reality. For example, do universals exist? An example @vjtorley alluded to: when a philosopher crashes through the window, what causes the window to break - the atoms, the philosopher, both, or something else? What is the nature of time - is there an objective “now”?

What is the Lutheran approach?

@Philosurfer? Help us out here?

Perhaps @AnonymousThomas can also chime in, but I personally I don’t think of any of these concepts in the same way that I think of atoms and molecules. They don’t readily produce falsifiable predictions that a conventional scientific theory would. Instead, they are conceptual categories within a framework of thought that we try to fit within what we know about empirical reality from conventional science and other means. The reason why we use these categories in the first place is because they seem to be very useful to cohere with our everyday experience of reality.

Again, this looks like a way of doing science while saying “This isn’t science”.

To what end, if not to make declarative statements about empirical reality? All I have seen from AT metaphysics is an attempt to resist conclusions of modern science which contradict or raise tension with certain theological claims, preserve a pre-modern understanding of empirical inquiry, and elevate theology and metaphysics above the science of the modern era.

Statements like this for example (emphasis here is mine).

Contemporary science’s progressive achievements crown God’s gift of human intelligence. Still, the whole point of this article has been to show that, unlike the inherent logical weaknesses of the “laws of physics,” which prevent them from ever rightfully enunciating universal certitudes, Thomism’s universally-certain laws of being, not only are logically presupposed by physics, but, indeed, supersede any modern physics’ claims that actually contradict them.

This is just downright medievalism. It’s based on a pre-modern understanding of the world, when people still believed in the aether, celestial orbs, a solid firmament, geocentrism, demonic possession, and witches.

But this is explicitly the language of science. So where’s the evidence for this coherence?

Echoing what @dga471 said already - there’s not really anything such as “no metaphysics”. What you would get instead is metaphysics that is simply presumed and not critically reflected upon. (In this case, we’re talking broadly about non-reductive vs. reductive metaphysical positions.)

Now, that’s probably okay for doing science, but it does lead to problems when it comes to interpreting scientific theories. E.g. do you want to say that tables, chairs, planets, etc. exist? Some people (philosophers, even!) argue that science tells us they don’t - in fact, that all we can really say exists is the mathematical structure found in physical theories. But this argument is based on the premise that what exists is what is described by fundamental physical theories, which is a metaphysical rather than a scientific thesis.

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I don’t understand what you’re talking about. You’ve been using the term “scientific claim” a lot, and I am really confused by what you mean by that. Seems like we just have very different ideas of what science is.

A-T philosophical concepts such as substances and forms have basis in empirical reality, but it is best called pre-science rather than science as such. It is based on empirical reality, but a only very basic sort of empirical observation. For example, I observe that there are things existing around me everyday - a chair, table, my computer, a tree, a dog. Do all of these things actually exist independent of my mind? Or is my mind only taking sense data from the atoms that make up the table and creating a mental structure which I then label “chair”?

Another example: when I observe a poodle and a St Bernard for the first time, I deduce that both are species of dogs. Is this merely an illusion, or is there really such a thing as the “essence” of a dog that is common to both? I don’t think these questions could be fully resolved by consulting a zoologist expert on dogs, for example.

I find A-T philosophy helpful to explain a few things. Some examples:

  • Understanding the nature of God (e.g. divine simplicity) and his relationship to the world (primary/secondary causality)
  • The laws of nature
  • Interpretations of quantum mechanics (i.e. wavefunction collapse as actualization of potential)
  • Philosophy of mind (the hard problem)
  • Philosophy of biology (understanding the unity of organisms)

I wouldn’t count myself as a full-blown Thomist on all of the above areas just yet, only that I think A-T philosophers have said things which give interesting and satisfactory answers to common problems.

I have nothing much to say against your sweeping accusations against A-T philosophy: only that I would say it’s best to respond to arguments that have actually been advanced here, by your discussion partners, instead of quoting random people on the internet.

Finally, I think that your scaremongering that A-T philosophy is pre-modern is not helpful either. I think we should not simply dismiss something just because it’s old, or associated with outdated views. I have nothing against appropriating parts of medieval thought and combining it with modern scientific findings if they satisfactorily resolve some problems.

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No I don’t think we do. You’re making claims about exactly what science makes claims about. Look at this stuff.

…[P]rime matter always exists in the real world as limited by its form, and hence having limited potency instead of infinite potency (as is the case with prime matter). Thus, when you die, you undergo substantial change, but there is a limited amount of things that you can transform into, because the matter of your body doesn’t have infinite potency. Thus, your corpse retains some similar properties to the current you but different in other properties. In A-T philosophy, form, not prime matter, “controls” above anything else about what changes can or cannot happen.

Look at all those empirical claims you’re making. Where does this all come from? Not experimentation, just people making things up. I will channel someone else here.

Well said.

It’s best called “pre-modern science”. It’s what we had before we had real science (the thing which works). When it is represented as still relevant science these days, we should call it “pseudoscience”.

In other words, some science stuff which actual science already explains (properly), and some theology.

I have no clue what you mean by scaremongering. To say that AT philosophy is pre-modern is a simple chronological fact.

I think it’s best to quote actual AT philosophers, especially if they happen to be fully qualified professors in the relevant field, who have held academic positions and have a long list of formal publications. I see no reason for you to dismiss such people as “random people on the internet”.

Just to be clear on this, you dismissed Dr Dennis Bonnette as a random person on the internet. Let’s look at his academic record.

At the end of 2003, Dr. Dennis Bonnette retired as Full Professor of Philosophy at Niagara University in Lewiston, New York, where he was also Chairman of the Philosophy Department from 1992 to 2002. He received his doctorate in philosophy from the University of Notre Dame in 1970, and taught philosophy at the college level for more than 40 years. Dr. Bonnette was a faculty member of the San Diego College for Women, Loyola University in New Orleans, and the University of Dayton, before coming to Niagara University.

He has participated in many radio and television programs on social, ethical, and theological topics in the course of his career, and written a number of scholarly articles as well as two books, Aquinas’ Proofs for God’s Existence and Origin of the Human Species. This last work has just been published in a second edition (Sapientia Press: 2003) with a new foreword by Dr. Michael J. Behe, Full Professor of Biological Sciences at Lehigh University and author of Darwin’s Black Box.

Dr. Bonnette is presently teaching free courses in philosophy at the Aquinas School of Philosophy in Lewiston, New York. See

Could you possibly be a bit clearer about your reasons for treating him with dismissive contempt? It seems to me that he knows a lot more about this subject than you do.

I agree.

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No, I’m not dismissing him with contempt, I’m just saying that my views are not necessarily his, and I’m defending my own views only. I don’t want to bother defending something that I never wrote in the first place, even if it is consonant with some of my views.

It seems that we’re done here, @Jonathan_Burke. I thought that you had changed to become less aggressive and more constructive as a discussion partner, but you have not.

What you actually said was “random people on the internet”. That’s how you classified him. You didn’t say “My views aren’t necessarily his, and I’m defending my own views only”. No one was asking you to defend his views. If I want accurate AT philosophy, I am better off going to him than you, am I not?

I think you need to realise that not everyone is easy to simply bulldoze into submission, and that sometimes people are not only going to disagree with you but they’re also going to tell you why. If you think this is “aggressive” and not constructive, maybe online discussions aren’t for you.

The problem is, I don’t think I’ve ever met a practicing chemist who cared about any of those questions. I’m not saying that metaphysics doesn’t have its place, and it certainly would make sense for philosophers to care about them, I’m just not sure that very many scientists care one way or the other.

I’ve never met a practicing chemist (i.e. not a philosopher of chemistry) who cared about whether chemistry was reductive. They have never really thought about it and it wouldn’t affect them either way. I would agree that any metaphysics for those scientists would be simply presumed, but I’m not sure if most of us even get that far. The only actually identifiable metaphysics I’ve seen is A-T, that’s why I asked for alternatives, I really don’t know of any.

I really think forums like this really overestimate how much philosophy scientists think or care about. Parts of physics get closest, to the point that I think a significant chunk of what we call physics today is, in fact, philosophy, but that’s pretty much it. The vast majority of scientists probably haven’t even heard of methodological naturalism, let alone thought about if it’s good epistemology. That’s why I’m pushing a little on the idea that scientists even generally have a metaphysics.


Well, OK, but going back to the reason we’re doing metaphysics in the first place is not necessarily to help chemists to do chemistry. This is why I’m not proposing A-T philosophy to replace chemistry or physics as taught in science departments. Even I only read about it for purely personal interest, not because it helps me directly to do science. I have a personal interest in it because it helps to unite and fit together different areas of knowledge and it helps to illumine some philosophical problems (including interpretations of QM, for example).

There’s nothing wrong with scientists doing science without caring or thinking seriously about metaphysics or philosophy of science. (Although the early generation of 20th century physicists - Einstein, Heisenberg, Schroedinger, etc. - did care much more about philosophy than the generations that followed them.) The problem is when some of these scientists start writing books which start to venture out of their field of expertise and comment on issues which require philosophical expertise, and they are caught out of their depth without them knowing it. Richard Dawkins and Stephen Hawking are commonly cited examples of this.


Yeah, I got ya. I am finding the discussion really interesting, I remember a bit of A-T from school but it was more in terms of history of thought rather than the way you are using it. I’m really glad you “debriefed” your conference with us.

P.S. I totally agree about scientists doing philosophy. I think to (re)gain credibility with the public we need to try to delineate between the results of science and interpretations of the world based on those results.


It seems like you’re taking an overly antagonistic stance here. I’m quite skeptical of A-T but I don’t see it as claiming to be science, but a metaphysical system. Of course they interact (so far not successfully for chemistry, in my view) but I’m not sure why you would call it pseudoscience. I haven’t seen anywhere in these threads where somebody claimed A-T metaphysics was “relevant science”, only relevant to science at the most.


I am asking precisely the same questions which are asked in the actual A-T literature. For example, see the article “Where is the Evidence for Thomistic Metaphysics?” by Klubertanz, which was published way back in 1958. The title is asking literally the same question I asked. I don’t think it’s antagonistic for me to ask these questions. I’m just repeating exactly the same questions which have been current in A-T literature for decades, and which are still discussed in the literature because they are still relevant. The fact that these questions still haven’t been addressed is one of the reasons for division within those who hold the A-T view in some way.

But I’m happy to modify my language to something more acceptable. Would it be antagonistic to say things like this?

  • “This, I have to say, is gobbledygook”

  • “I’m afraid this won’t do”

  • “Seriously?”

  • “On an Aristotelian-Thomistic account, this makes absolutely no sense at all”

Is this language totally ok and non-confrontational? Thanks.

Before the modern scientific era, A-T was science, and was billed as science. During the early modern scientific era, A-T was still regarded as science, and still billed as science. In the later modern scientific era, when it became clear A-T was falsified science, there were several responses. These are four of the most common, from what I can see.

  1. Deny that A-T science have been falsified, and argue that it is modern science which is wrong. This view is still promoted by some A-T proponents.
  2. Accept that some parts of A-T science have been falsified, but claim that other parts have not, and argue that modern science is incomplete without A-T science. This is a more common view.
  3. Accept that A-T science have been falsified, but claim that A-T metaphysics is still valid. This is quite a common view.
  4. Deny that A-T was ever about science, claim it was always only about metaphysics and never made statements about the natural world, and claim the metaphysics is still valid. From what I can see, this view is totally on the fringe.

When people make the claim that X has changed into Y, but there is absolutely no physical evidence that X has changed into Y, so they claim the substance has changed but the accidents have remained the same, that’s pseudoscience (never mind the fact that Thomas contradicted Aristotle on this point). The very claim that objects consist of changeable accidents perceived by the senses and unchangeable substance perceived only by the mind, and that these are independent of each other, is pseudoscience.

The title of the original thread was " A Thomistic Approach to Chemistry", not “Thomistic metaphysics orthogonal to chemistry”, or “How Thomistic metaphysics is relevant to chemistry”. The thread started with the fact that the Thomistic view of chemistry involves a specific approach to the natural world, which differs significantly from the approach taken by modern science. The original thread started with a post which made scientific claims, and which used A-T statements about nature in order to address matters of scientific investigation.

  • “hydrogen and oxygen only exist virtually in H2O, which is its own thing, with different properties than either hydrogen and oxygen”

  • “only macro-level objects with thermodynamic properties exist. Elementary particles/fields and even atoms for the most part exist only virtually as part of a greater object”

  • “thermodynamics cannot be reduced to a collection of discrete, individual particles”

These are not metaphysical statements about “the philosophy of chemistry”, these are specific empirical claims about the physical properties of objects in the natural world.

You may nor may not know that A-T is still being used by certain A-T proponents to try and resist the conclusions of modern science. For example, it is used to deny evolution, and modern science as “materialist” and “reductionist”.

My hope is that the ID movement can move toward an Aristotelian and Thomist critique of Darwinism. It is the most effective way — I think the only really effective way — to kick out the foundation of Nominalism and Mechanical Philosophy on which Darwin and his children built their fiction.

In fact when people raise objections to modern science on the basis of its alleged “modernism”, “materialism”, “Epicureanism”, and “reductionism”, A-T is not far behind, and is often cited in support of the argument (we’ve seen that happen repeatedly on this forum). The primary motive of people who raise A-T in discussions of modern science, is virtually always religious. Entire swathes of Catholic doctrine depend on A-T epistemology. That’s why arguments like this result.

Since A-T’s claims on matters such as natural law are used to inform theology and morality, it has a direct impact on many other aspects of life. Historically it has not only crippled scientific progress, but upheld misogyny, imperialism, colonialism, and a host of other evils. Even today it remains immensely influential on social and religious policies on issues such as reproductive rights and gender rights, which has a massive negative impact on the daily life of millions of people. In my view A-T is not only pre-modern science, but incredibly bad theology and extremely poor morality.

Except that’s actually not what you asked. You asked (I’m quoting here):

  • On what demonstrable basis does AT make all these scientific claims?
  • Where’s the actual evidence for all the claims about “prime matter”, and “accidents”, and “incidents”, and “substance”, and “form”, and “properties”, and God’s mysterious role in chemistry and physics?
  • What experiments do AT theorists make to test these claims?
  • How is AT science actually carried out?
  • Where are all the AT scientific research institutes making groundbreaking discoveries with AT science?
  • How is AT any different to astrology?

All of those questions are loaded, and none of them are “Where is the evidence for Thomistic metaphysics?” I’m going to deal with why these are all loaded questions below, but can you not see how these questions are making assumptions about your dialogue partner and putting them immediately on the defensive?

This is well laid out and useful information, the problem is that I haven’t seen anywhere in the two current A-T threads where somebody has suggested that A-T was science. I’m pretty sure it was universally referred to as metaphysics and mostly in the present tense. You’re railing against a straw man: A-T was considered akin to science (natural philosophy) of the in pre-modern European thought. But no one has proposed in our discussion that A-T thought replaces science (it’s methods or results) that I can tell. That is why your questions seem loaded and out of place. It’s perfectly legitimate to ask “what kinda of evidence is there for A-T metaphysics?” but you are forcefully demanding people to answer questions about something they never claimed (that A-T is science) which causes people a lot of frustration.

I am fairly certain that it was assumed that “A Thomistic Approach” assumes metaphysics, and clearly everyone but you got that. You could have just said “hey, are we distinguishing between A-T as metaphysics and A-T as science?” but no, you had to just blast away. I am a chemist, I have a PhD in chemistry. I have not seen anything in these threads that suggest that they are trying to change science, only how to understand it metaphysically.

None of those statements were scientific claims. You could have simply asked if they were trying to make a scientific claim, but you didn’t. For instance, it was made clear that they aren’t saying that atoms aren’t there. I still don’t know what “virtual” means, but I haven’t seen any suggestion that they are trying to contradict modern science. I think the science is inconsistent with their metaphysics, but that’s not the same thing as saying that they are making scientific claims.

No, they aren’t empirical claims as far as I can tell. If they had said “hydrogen gas and water have different properties because water is flammable and hydrogen is not”, that would have been a scientific claim that was wrong. Instead, they used the scientific facts to make a metaphysical interpretation. You need to engage with their metaphysical argument instead of what starts to look like a red herring or straw man fallacy.

And when somebody on PS makes those claims, then feel free to address them. In neither of the current A-T threads has any of that come up, so it’s pretty much irrelevant.

OK, so now you want to add slippery slope and guilt-by-association to the list of fallacies? :slight_smile:

This is why we added " 3. Don’t assume motives" to the guidelines. I can understand, if you think the way you do about A-T, that you would be wary of it and passionate about addressing it. However, in a group as diverse as PS and it being an online forum where body language and tone aren’t there for us to judge other’s reactions, we need to be especially conscious to address only what people write. @dga471 went to a conference about how Thomist metaphysics interacts with chemistry, that’s it. It’s clear he’s trying to see if A-T can be useful. If you really feel like you have to say something, a simple “In my personal opinion, A-T thought can lead down some very negative roads, so I generally avoid it.” and then be ready to walk away from the discussion.


This is the most common view among the Thomists I’ve encountered, and I would say an eminently defensible one. There are a few who use Thomism to argue against contemporary science, but they are a minority (more on this later).

You seem to be talking about a Catholic interpretation of the Eucharist here (transubstantiation), where the wine and bread substantially changes into body and blood but the accidents of wine and bread remain. First, among Catholics this is usually talked about as a miracle anyway, and thus a red herring that has limited relevance to our discussion on how Thomism and science interact. (If you want to argue that miracles are a form of pseudoscience, then that’s a different debate entirely, and not one that is only of relevance to Thomists.) Secondly, as a Protestant I don’t hold to this doctrine; in fact some Reformers objected to transubstantiation for similar reasons to what you outlined here, that it is philosophically incoherent. (They probably wouldn’t call it pseudoscience though - it was thought to be incoherent even by the standards of Aristotelian philosophy.)

So far, I find that the majority of Thomists I’ve met accept the scientific findings of evolution entirely, with markedly much less reluctance and qualifications than many evangelical Christians. In the Thomistic conference I attended, there was an entire dedicated session led by Thomist biologist which spent a lot of time arguing for the explanatory power of evolutionary theory (and even fending off objections from an apparent creationist in the audience). Yes, there are a few who try to use Thomism to argue against evolution (Fr. Michael Chaberek is an example, and I’ve seen stuff from Wolfgang Smith or his followers which look like they reject Special Relativity), but they seem to be the minority among Thomists.

In general, Thomism and ID don’t mix well, even though they both believe in the existence of teleology in nature. (This is an interesting topic that deserves a thread on its own.) ID people adopt a modernist, mechanistic metaphysics and attempt to read extrinsic teleology from nature, which necessitate them to argue against evolutionary science. They view the Designer like a human watchmaker who tinkers with the components of nature to make new artifacts - hence the famous Watchmaker argument by Paley.

In contrast, Thomists tend to see teleology as intrinsic to nature - operating at the level of the laws of natures themselves. They affirm the usefulness of modern science to investigate the material and effective causes of evolution. But Thomists believe in four causes - formal, material, effective, and final (teleological). It is the first and the last which are in the domain of metaphysics, not mechanistic science. Thomists believe that final causes exist in the case of a stone falling down to the Earth, even though we already know how to plot its trajectory using Newtonian mechanics. Thus, there is no conflict between having a scientifically complete account of evolution yet also thinking that a teleological account is needed.

The first two statements are philosophical statements, as virtual existence is a metaphysical, not scientific concept. The proof of this is that when I’m taking about virtual existence, I never cease looking at the empirical facts discovered by modern science and try to fit virtual existence to that.

The third statement is indeed a quasi-scientific statement, and the evidence for that is in Koons’ paper (Hylemorphic Escalation) which I had linked in the other thread. He uses, among other things, the Stone-von Neumann theorem to argue that you cannot reach the continuum limit by just using finite systems.