by Gideon Lazar
One of the many problems with contemporary natural science is that it is filled with materialism. Everything is simply composed of billions of small atoms, which are themselves composed of smaller particles. Greater substances such as biological organisms are merely just more of these atoms. Properly speaking then, biological organisms don’t even exist as real substances according to this atomism. They are just a slightly different arrangement of protons, neutrons, and electrons.
Atomism as a theory is not new. It was theorized by many ancient philosophers before the coming of Christ, such as Democritus. One of the most complex forms of this was in Lucretius, who in De Rerum Natura puts forward a view that random atoms collided over time to form all the creatures of the world. Those that were fit survived and those that were not fit did not survive. However, many in the ancient world rejected such a view. For example, Aristotle was very critical of atomist and transformist theories of nature. Aristotle instead put forward a hylomorphic (matter and form) and teleological (final causality) account of nature. This we will talk about here.
After the coming of Christ, the Church in general preferred these non-materialist accounts put forward by philosophers such as Plato, Aristotle, and Cicero. However, even these accounts still had many issues, and over the centuries there have been various forms of reception of pre-Christian philosophy.
The purpose of this essay is not to resolve internal disputes within the tradition about the details of a non-materialistic account of nature. Rather, I will here seek to put forward an Aristotelian/Scholastic account of nature, and specifically biology. I hope this can serve as a resource to scientists for the renewal of an anti-reductionist (that is, not reducing animals to a set of atoms) biology.
What is Hylomorphism?
In contrast to atomism, Aristotle proposed hylomorphism. Hylomorphism theorizes that all physical things are made of two parts: matter (Greek hylē) and form (Greek morphē). Matter is what is in potency and form actualizes it. As an analogy, consider a lump of clay. On its own, the lump of clay is nothing. However, it has the potential to be many things. A sculptor (the efficient cause) places form into the matter, changing it from a lump of clay into a sculpture. It has now changed form but has retained the same matter of clay. Strictly speaking, this is only an analogy as the sculpture is a human artifact. A real change in substance (what something is) would be the formation of the clay itself. But the analogy is a helpful illustration of what hylomorphism is and why it is true. Matter has the potential to be anything but is only actually one thing into which it is formed. When something changes from one substance into another, it changes form but retains the same underlying matter. Thus, we can say that when for example a flower dies and decomposes, it actually changes into something new even if it retains the underlying matter. Any other account of change must deny that the matter is actually formed into anything (atomism/reductionism) or deny that any underlying matter exists and therefore nothing can actually change from one thing into another (Eleaticism).
Hylomorphism is a view which we can reason to from basic principles, and so strictly speaking no experimental evidence for it is necessary. However, it is quite impressive that quantum physics seems to have vindicated this Aristotelian metaphysics, as Werner Heisenberg himself noticed.  It is also important to note that rejecting atomism is not a rejection of the existence of “atoms” in the modern scientific sense of the term. In fact, “atoms” are themselves now known to be composed of smaller particles, and so they are not the indivisible atomoi (Greek for “uncuttable”) of philosophical atomism. Rather, hylomorphism is a rejection of the bad philosophy that has been disguised as the results of experimental science by enlightenment philosophers.
Hylomorphism and Life
Hylomorphism also applies to living beings.  Aristotle recognizes three kinds of souls in De Anima: vegetative, sensitive, and rational. Vegetative souls provide the power of nutrition, growth, and reproduction. All living beings take in resources and use these to grow and reproduce. Any failure to do these three is considered a defect of that particular creature and is not indicative of biological organisms in general, even of their own species. By vegetative should not be understood only the modern taxonomic classification of Plantae, but rather all organisms whose biological powers include only these powers of the vegetative soul. Sensitive souls add the powers of sense knowledge, imagination, appetition, and locomotion. Animals, those beings with sensitive souls, take in sense knowledge from the outside world. They then somehow have this sense knowledge in them (imagination) and react to it (appetition). How exactly this works has been the subject of much debate even within scholasticism.  Of course it is difficult for us to place ourselves into the minds of non-human animals. Regardless, we can tell from their behavior that they are more intelligent than plants or inanimate objects, but do not possess the full rationality of humans or angels. After taking in this information, the animal moves in reaction to it.
Finally, humans and angels have rational souls. Rational souls grant men and angels an intellect and free will. While some accounts of hylomorphism, such as St. Thomas Aquinas’s, place more emphasis on the intellect, and others, such as Bl. John Duns Scotus’s, place more emphasis on the freedom of the will, all hylomorphists agree that the intellect and will together make man a rational animal, distinct from the other animals not just in the quantity of the powers of his soul, but in its quality.
What makes the hylomorphic account of the soul different from a dualist account is that the soul is the form of the body.  Just as the substantial form of water grants the prime matter which it informs the powers of water, such as surface tension, the soul grants the prime matter which it informs biological powers. This is because the powers of souls, such as growth, self-locomotion, etc., are found operating not in a separate, disembodied world but within the matter which it informs. This rules out the objection that because the properties which Aristotle lists are found by scientists in matter that it means the being does not have a soul. Scientists are not studying prime matter in an organism. They are studying matter informed by a soul. Since the soul is the form of the body, most souls cease to exist upon death, just like the form of an inorganic substance ceases to exist when it undergoes a chemical change. However, since rationality can exist even apart from the body, as is evidenced by the angels who have no bodies but have rationality, the rational soul of humans can continue to exist after death.
One other possible objection is that we can find distinct substances within a larger organism, such as a heart within a body. It would seem that these substances should have their own forms. However, even though Aristotle held that there is only one substantial form within a substance, one can grant that there are more and still hold to hylomorphism. For example, Scotus developed a very robust theory of the plurality of forms.  Whether forms are always single or multiple within a substance also answers the question of whether higher types of biological souls contain the powers of lower ones or if a biological organism can actually have multiple types of souls.
Scripture and Hylomorphism
While hylomorphism is a philosophical doctrine and so should be proved through reason, it is consonant with what we find in scripture. This is most clear with scripture’s doctrine of man. Man only becomes a living being once God breathes into him a soul (Gen 2:7). Before that, he is just a lump of dirt in the shape of a human body. The soul of man animates the body by giving it the powers of life. In addition, through the doctrine of the bodily resurrection, scripture teaches that it is best for man to be both body and soul. If substance dualism were correct and the soul were just a distinct substance added onto the substance of the body, since the highest faculties of man are in the soul it would not be bad for man to spend his eternity as a disembodied soul. However, God shows through the bodily resurrection that it is not good for man to be without his body. This is because the soul is the form of the body and so a soul without a body is incomplete.
What about other living organisms? Strictly speaking, the biblical definition of life, chayim, is only applied to animals and humans. This is because they given the breath, nephesh, of life (c.f. Gen 1:30). Thus, nephesh in the language of the Biblical authors seems to correspond with what philosophers would call the sensitive soul. In addition, scripture refers to life as being “in the blood” (Lev 17:11, 14, c.f. Gen 9:4). It seems the existence of blood may be the biblical division between the animals, which have sensitive souls, and the plants, which only have vegetative souls. Plants are still seen as growing and reproducing, so it is not wrong to say that in a philosophical or biological sense, plants are alive. Indeed, the Bible frequently uses the seeds of plants as an analogy for human reproduction. However, in a theological sense, plants are not alive because they lack a nephesh, or sensitive soul.
Another important aspect of Aristotelian metaphysics which should influence our biology is final causality. So far, we have already discussed efficient (who or what is causing the change from outside), material (what it is made of), and formal (the form informing of the matter) causes. But all of these are for the sake of something outside itself, the final cause. A carpenter (the efficient causes) takes wood (the material cause) and transforms it into a table (the formal cause) so that things can be placed on it (the final cause). Without discussion of final causality, there is no purpose for the efficient, material, or formal causes.
Modern science attempted to stamp formal and final causality out. In Francis Bacon’s New Organon, a foundational work of the “Scientific Revolution” in which he sought to replace the old Aristotelian Organon, he argues that all science should study only material and efficient causes. This means that there is no intentionality in the physical universe. Darwin too followed this view, arguing that all adaptation is the result only of random mutation and selection. That is, a giraffe does not have a long neck to reach the leaves, but that all giraffes with short necks were outcompeted by giraffes with long necks.
Despite Bacon and Darwin’s attempts, we still regularly speak of final causality. We say that hands are for grasping things. We say that chlorophyll is for photosynthesis which is for the plant to receive nutrients. Every biological operation is for the sake of something. This should cause us to recognize the beauty of God’s creation. Everything was made for a purpose. Nothing is by chance.
Bringing hylomorphism and final causality together, we can see that animals exist primarily as substantial wholes whose parts are ordered to the good of the whole.  The eye exists for the sake of the cat to be able to see things. Modern science sees only the motion of atoms that causes the appearance of an eye seeing things for the cat. It misses that the eye genuinely exists for the good of the cat, and that the eye cannot be understood on its own (for then it would cease to act as an eye).
It seems then that neither theology nor philosophy can support a reductionist or atomist account of life. While certainly much more could be said on this topic, I think this is sufficient for the basic issues at hand. I wish to leave it here then for scientists to use to better investigate the natural world without the limits of materialism. Indeed, as pointed out earlier, recent discoveries in physics have pushed away from a materialist account and towards a hylomorphic account. Hopefully similar work can be done in biology to better understand the creation so we can better praise the Creator from whom all life comes.
 Werner Heisenberg, Physics and Philosophy: The Revolution in Modern Science, (New Tork: Harper Perennial, 2007); c.f. Wolfgang Smith, The Quantum Enigma: Finding the Hidden Key, (San Rafael, Angelico Press: 2005); William M. R. Simpson et al., Neo-Aristotelian Metaphysics and the Theology of Nature, (New York: Routledge, 2022).
 For a more detailed defense of biological hylomorphism, see David S. Oderberg, Real Essentialism, (New York: Routledge, 2007), 177-260.
 Anselm Oelze, Animal Rationality: Later Medieval Theories 1250–1350, (Leiden: Brill, 2018).
 This was even made dogma at the ecumenical Council of Vienne (1311-12).
 Thomas M. Ward, John Duns Scotus on Part, Wholes, and Hylomorphism, (Leiden: Brill, 2014).
 A very good example of how to approach biology in this manner can be found in Christopher O. Blum and John A. Cuddeback, Nature’s Beautiful Order: An Introduction to the Study of Animals by the Classical Naturalists, (Louisville: Memoria Press, 2015). I would highly recommend this book to any biologists for an example of the methodology of this article in practice.