A Thomistic Approach to Chemistry

[Jordan (Jordan Mantha)]

@AnonymousThomas, first of all, thank you so much for taking the time to explain all this. My exposure to A-T came from a scholastic-leaning homeschooling mom

While I enjoy my share of philosophy, I get a lot more out of epistemology than metaphysics. For some reason I just can’t seems to figure out the point of ontology and to some extent causation. I’m not trying to be overly argumentative, but I just don’t get A-T (or perhaps even metaphysics as a whole, for that matter).

@AnonymousThomas

As far as ontological irreducibility vs. epistemological irreducibility in working out whether chemistry is reduced to physics, the point raised by Bishop and other anti-reductionists is that we cannot explain the behavior of higher phenomena solely in terms of lower level phenomena. You must use information outside of physics. This isn’t some armchair speculation, it is an argument grounded in current scientific practice. This sort of failure shouldn’t happen if reductionism was true.

How do you know that chemistry is higher phenomena than physics? I’m a chemist who teaches both chemistry and physics undergraduate course and I have a hard time distinguishing between the two fields much of the time. On the ground level, it’s increasingly difficult to tell physics, chemistry, and biology apart so I have difficulty figuring out why reducibility is concern.

I understand the issue of reducibility of chemistry to be, more specifically, the question of whether all chemical phenomena can be completely explained by quantum mechanics. The trivial answer is, of course not, we don’t have analytical quantum mechanical solutions to any multi-electron systems (essentially anything other than hydrogen atoms). On the other hand, I don’t know of any chemical system where quantum mechanics does not apply. The argument comes off a little like “irreducibility of the gaps”. Don’t get me wrong, I lean towards irreducibility of chemistry (and as a chemist, selfishly towards the reducibility of biology ) but I don’t know that it matters one way or another since it would probably be just as easy to expand the definition of “physics” to include the chemistry bits that aren’t currently reducible and poof it’s reducible again. The definition of physics and chemistry seem more flexible than the metaphysical systems.

@AnonymousThomas

Here’s a few more examples of emergentism.

Covalent and ionic bonds cannot be separated in exclusive concepts.

Hybrid orbital representation does not fit into quantum mechanics.

Molecules shouldn’t have a shape according to QM.

Hmm, but I think generally the idea of covalent and ionic bonds are considered a “less correct” model of reality than the quantum mechanical “areas of varying electron density between nuclei”. The idea of a chemical bond is just a convenient approximation, much to the chagrin of my students who memorized rules for Lewis structures.

Hybrid orbitals are similar. They are a convenient rough approximation we tell freshman and sophomore chemistry students, but I don’t know of any chemist that thinks orbital hybridization is more accurate than molecular orbital theory, for instance.

I’m not really sure what “molecules shouldn’t have shape according to QM” means, but computational chemists certainly use ab initio quantum mechanical calculations to find the shape of molecules. It’s entirely possible I’m missing something here.

@AnonymousThomas

Anyways, one way of looking at atomism is that atoms don’t undergo any substantial change when becoming part of a new substance. They are the same thing before and after. The AT position is different. Atoms don’t have their own causal powers after a substantial change. The causal powers of the atoms belong to the new substance, not the individual atoms. It seems like you guys keep misunderstanding virtual presence as potential presence. They are not the same thing.

I don’t think anybody is arguing that atoms don’t undergo changes when they bond to form a molecule, but I would certainly argue that they retain their identity within the molecule. There is a stark difference between having two H atoms and an O atom within a molecule and having a Ne atom within a molecule, even though they contribute the same number of subatomic particles (give or take a couple neutrons). The properties of water and hydrogen/oxygen gas are very different, but they aren’t unexpected or unexplained by physics.

I have no idea what it means for atoms to cease to have have causal powers. I don’t have a firm grasp of what causation really means but I’m thinking here about vibrational modes within the water molecule. If the hydrogen and oxygen atoms have no causal powers, how are there motions of the nuclei relative to each other (i.e. one atom causing a movement in another atom due to electrostatic repulsion) if all the causal power is in the water molecule as a whole?

@AnonymousThomas

“Elementary particles/fields and even atoms for the most part exist only virtually as part of a greater object” is not the same as saying “Thomists are reluctant to think of elementary particles and fields as individual substances is because in practice, we almost never (if at all) find them existing by themselves (instead of as part of some other substance).”

OK, that makes more sense, but I’m still hung up on the fact that the chance of finding an atom existing on its own vs a part of a molecule is entirely dependent on the properties of the atom (e.g. electron configuration).

@AnonymousThomas

When Thomists say that atoms don’t “actually” exist in a substance, we aren’t saying anything like the atoms aren’t really there. We just mean that atoms don’t exist as substances. For example, the hydrogen and oxygen exist as parts of a water molecule, which is a kind of lesser existence. Of course we can “see” these atoms. But we see them as parts, not as substances in their own right.

So how is that different than saying “molecules are made of atoms”?

@AnonymousThomas

In the case of H2O, one way that we can know that atoms are not substances is that hydrogen is flammable while water is not. Or rather hydrogen gas is flammable while water is not. Hydrogen should behave the same whether it is “actually” part of H2 or H20 if it was actually a substance. The same goes for oxygen. But neither does behave the same, so we should conclude that these atoms are only virtually present which explains why only some of their powers seem to carry over.

You lost me here. Why would we would think that H₂O and H₂ and O₂ need to behave the same? A hydrogen atom in H₂ is in a different electronic environment than a hydrogen atom in H₂O, but we know that both are hydrogen atoms (spectroscopically). Water is a liquid because of the electronegativity difference between the oxygen and hydrogen atoms and the small size of the hydrogen atom which combine to create exceptionally strong dipole-dipole interactions between the water molecules. Molecular hydrogen and oxygen are a gases because there is no electronegativity difference, therefore no dipole, and therefore only transient intermolecular forces, which are not generally strong enough to overcome the thermal energy of collisions. In all of this, nothing is unique to the molecule per se and instead depends strongly on the identity of the atoms involved. I don’t get why anybody would expect atoms to behave the same in radically different environments. To me the question is, is there something fundamental about the identity of the atom that changes as the molecule forms, and the answer is a resounding no! A foundational principle in chemistry is that atoms don’t change identity under chemical reactions, including the formation of molecules. You don’t put two hydrogens and one oxygen into a water molecules and get one hydrogen and a fluorine out when you break it apart.

@AnonymousThomas

Now, something has account for limiting the powers of each atom in H20 as wells as the emergence of new properties, and Thomists think that is the form of H20. Appeals to structure or configuration of oxygen and hydrogen in H20 in order to explain the properties of water are really another way of using specific relations between the parts and the whole- in this case, the form is what gives the molecule something beyond the sum of its parts.

What does “limiting the power of each atom in H2O” mean? To me, “specific relations between the parts and the whole” sounds a lot like “atoms combine to form molecules”, I don’t know what “substance” and “form” and A-T add to our understanding of water.

@AnonymousThomas

The form is something “higher” that is responsible for uniting and ordering (i.e. bonding) its parts (atoms) as a new substance.

This doesn’t make any sense to me, where would this “form” come from? All the experimental and theoretical evidence I’m aware of says that atoms unite and order themselves into molecules.

@AnonymousThomas

Here’s some further reading

Thanks again for all the work on this. It’s probably obvious I haven’t thought about the metaphysics of chemistry much.