Where does the idea of animal souls being destroyed come from?

Okay I know this is a topic that can elicit strong feelings. So anyway, I know St Thomas Aquinas talked about a rational soul (a human being) which is never destroyed and then an animal’s soul or a plant’s soul, which is a material soul and is destroyed after the creature dies. This continues to be frequently cited to the present day in Catholic circles.

My question is: where does this idea actually originally come from? I’ve heard Catholic apologists mention it before, but it’ was just “St Thomas Aquinas said this, this, and this” and that was about the extent of it. St Thomas Aquinas wrote it down, but where did Aquinas get it from? Did he reference something from the scriptures that made him conclude this? Did he quote an earlier saint from antiquity or philosopher to support this view? If so, what was that person’s reasons for believing such and such?

Has there ever been any Ecumenical Councils that broached the subject of animals and plants? Any encyclicals? Any insights would be good.


St. Thomas gave a systematic justification based on natural theology (as opposed to revealed theology or an appeal to authority) for why human souls are immortal and non-human souls of living things are not. I’m certain he is not the origin of that doctrine, but I’ll need to research.

I think this is one of those ideas that just makes sense. It is not a Christian exclusive. How else would one justify eating animal meat? Both Aristotle and Socrates believed only the human soul was immortal. I am sure St Thomas Aquinas was aware of that.

Well, I want to avoid appearing like I’m taking a side, but why would a rational soul (i.e. a soul capable of making good and evil moral choices) be exclusive to life after death and a non-rational would not be? Why wouldn’t plants and animals theoretically not be able to continue to exist after death in a state of natural happiness? A rational soul - choosing good and evil - can experience supernatural happiness in the Beatific Vision or supernatural misery from being separated, but wouldn’t non-rational souls still be able to experience a state of natural happiness?

I just don’t see the answer automatically being “they die” is all. That just seems like an assumption imo, but I need to read more about what Aquinas specifically said.

Is this a question on St. Thomas’ explanation via natural theology or a question of what scripture and pre-Aquinas patristics say on the matter?

Anything you know would be helpful, if you’re up for it.

I don’t have the Summa available to me.

Well, St. Thomas’ explanation I can write about off the cuff, though it’s a broad topic that requires knowledge of both hylemorphism and St. Thomas’ philosophy of the mind. Let’s see if I’m up for this tonight…

The hylemorphic explanation of material substances is that they are metaphysical composites of form and prime matter. Form and prime matter are co-principles that, generally speaking, cannot exist independently. They are not substances in and of themselves. A form does not subsist on its own, it either exists in a material substance or mentally in an intellect. Prime matter also cannot subsist in itself, but always exists as a kind of thing defined by some form. When hydrogen and oxygen are fused into dihydrogen monoxide (water), the forms of hydrogen and oxygen do not persist. They’re gone and the new substance has the form of water. And when water is split into hydrogen and oxygen the form of water is gone and the new substances exist under the forms of hydrogen and oxygen (more specifically the whatever the stable molecules are). The form that was previously present isn’t immortal. It doesn’t separate from the prime matter and become its own thing. It ceases to exist once the material operations of the substance cease.

In hylemorphism, the word “soul” is just a specific use of the word “form”. It’s used to refer to the form of living things, where what differentiates living things from non-living things is immanent causation in the substances. A soul is not an additional vital principle. It’s just the form, defining what a thing is, bringing to the table the operations that define a thing.

Souls (forms of living things) are divided into three tiers of powers. The vegetative powers which include nutrition and growth. Plants fall into this category, but on a metaphysical classification level so do fungi and certain unicellular organisms. The next tier is the sensitive powers, which include sensation (as a unified organism) and locomotion. This is exhibited by what we call animals. Note that the forms of animals include both vegetative and sensitive powers. The final tier are the rational powers, which include intellection. This is possessed by human beings, who also possess sensitive and vegetative powers.

Now, the key point is that vegetative powers and sensitive powers are entirely explainable as material operations. And when these material operations fully cease there is no persistence of the form which gives rise to these operations. A substantial change occurs in which there was a living thing but is no longer, the formal principle of the substance as a unity is replaced by another (or others, really). The same as how the forms of hydrogen and oxygen no longer persist after they undergo a substantial change into water.

Continued in the next post


Intellection, however, is not reducible to a material operation. I don’t know that I want to do a full write-up, but to clarify, St. Thomas did not equate intellection to consciousness. A unified sensory experience, perception (including the “qualia” the rationalists made such a big deal of), memory, the ability to estimate, even imagination are considered entirely reducible to material operations as each of these concerns the particular. Even emotions are material operations, not immaterial. St. Thomas attributes all of these things to animals and holds that these material powers play an important role in our own consciousness. Intellection refers specifically to what is not particular. It refers to the universal form abstracted from all particularizing features, abstracted from material conditions. This is the ability of rational animals to grasp universals after experiencing particular things, and this allows for things such as our conceptual language, philosophy, etc… Since intellection is not reducible to material operations, it therefore is an immaterial operation, and what is immaterial is not corruptible. It has no tendency to decay, it has no tendency to come apart. Therefore, even when material operations cease in rational animals the immaterial operations do not, and since the operations persist so does the form (soul) of which they are a power of.

A few more points of clarification, as I said, the material operations cease. The material processes of memory, estimation, sensation, imagination cease after death (or at least they would naturally do so, whether God provides some type of additional support isn’t a question answerable by natural theology). What persists is only the operations of intellection (without any sensory input or change, just the sum total impressions, knowledge, and a direction of the will that doesn’t get any new info or competing appetites). Apart from the body (or divine intervention) we become pretty handicapped beings. Immortal, in that there is persistence, but we lose most of the operations that naturally follow from being human. It’s just this one little facet of operations/properties that don’t decay. We reject any Platonic or Cartesian idea of the soul being ‘what we really are’ and the body just a machine. We are not complete without the soul as the form of a body. And hylemorphism rejects the notion of the soul as an additional vital principle to the formal principle (which is something all material substances have, alive or not) and prime matter. Thomists argue about whether what remains after death can even be called a human being (even if it is a human soul) or a substance in itself.

But anyway, what distinguishes the form of a human being from the form of a rose or the form of a dog is that a human being has properties which point to immaterial operations, whereas roses and dogs have properties entirely explainable by material operations. And what is immaterial is not corruptible (in the sense of a tendency to decay or towards ceasing to exist).


Thank you very much :slight_smile: That was fun to read, though I’m not sure I’m 100% clear on the difference between intellection and material processes. It seems like the only thing about human beings that couldn’t be explained by material processes is free will, because absolutely any scientific explanation involves causality and free will is not about causality.

But free will seems to be based on revealed truth rather than on anything we can observe naturally.


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I have never see a Catholic dogma of faith about souls of animals other than the rational soul of man.

Fundamentals of Catholic Dogma, Ludwig Ott:

  • Man consists of two essential parts-a material body and a spiritual soul. (De fide.)
  • The rational soul is per se the essential form of the body. (De fide.)
  • Every human being possesses an individual soul. (De fide.)

Catholic Encyclopedia

… the rational soul, which is one with the sensitive and vegetative principle, is the form of the body. This was defined as of faith by the Council of Vienne of 1311 …

Maher, M., & Bolland, J. (1912). Soul. In The Catholic Encyclopedia. New York: Robert Appleton Company. http://www.newadvent.org/cathen/14153a.htm

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It’s not a Christian exclusive to allow eating meat, no. But you’re implying that pretty much all religions justify eating animal meat. Actually many don’t: Jainism, Sikhism, Hinduism, and Buddhism are some prominent examples of religions that prohibit consumption of animal meat. (In practice some followers of Hinduism and many followers of Buddhism do eat meat, but in their theology and metaphysics they argue against it.)

Not ALL of course. For the ones that do justify eating meat, it follows that only the human soul is immortal.

It is a very impractical idea. If you are a farmer in India, you know that when you till the soil you are going to kill some earthworms, no matter how careful.

The injunction is against intentional killing or maltreatment. It doesn’t apply to earthworms killed by the plow, or ants drowning when they’re washed out of a bowl.

Moreover, vegetarianism is hardly impractical. Hundreds of millions of people have no difficulty making it work, and still eating very tasty food, and living in excellent health.


In “Summa Theologica” St. Thomas Aquinas seems to refer to “De ecclesiasticis dogmatibus” by Gennadius of Marseille.

As far, as Scripture is concerned, it looks like one of the most relevant verses is Ecclesiastes 3:21: “Who knoweth if the spirit of the children of Adam ascend upward, and if the spirit of the beasts descend downward?”…

It does not look like Ecumenical councils dealt with such a matter, since, well, while the possible answers might gladden or sadden someone, they seem to make little difference for just about any decision (with possible exception being writing about this question).

That’s not what I’ve heard but I’m no expert in Hinduism.

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