 further back.
There is no transition between an irrational and a rational soul. If it could be conceived, as the evolution believers generally want to, it would mean the distinction were a superficial and otherwise illusory one.
And lacking a first man would also give no significance to any one man's sin so that innocent people suffer for it for being his offspring - Original Sin and its consequences only make sense if there was a real Adam, and a real Adam only makes sense if God created him with no biological ancestry, for the reason explained.
Thank you Gideon!!! This is something we speak with in our Thomist circles and that's the very reason why we are not evolutionist, because it is in the end a philosophical and metaphysical problem, and you are correct; the notion of having something like evolution, meaning accidental changes that end up changing the essence of a species and turning it into another one it's very problematic for our Catholic teaching of the eucharist.
But isn't everything, in the end, a philosophical problem? That's why when you get well-versed in something you get a PhD, and are therefore a philosophic doctor of your field.
Also, you're not changing the substance (I think you mean) of anything through accidental changes, because the thing that has the new substance and that newly comes into existence never existed before and therefore had no substance prior to this macroevolutionary one.
Also, accidental changes can beget substantial changes. First of all, this isn't even necessary to prove in macroevolution, because you're dealing with multiple different existent beings. Second of all, even if it were necessary, it's perfectly tenable. Cutting a cat in half is an accidental change that causes a substantial change, because the cat has now died. Turning a pile of wood into a chair changes it accidentally and substantially.
@Jack that's a very simplistic argument and it's only analogous, an being with living soul is not the same as a souless object. I mean chopping a dog's tail doesn't turn him into other species of dog. You are making the transhumanist claim, adding some accidental things to a human (robotic limbs, neuralink, or whatever) will change the human soul into the soul of a different being. And in your example of chopping a cat you begin the process of separation between the cat's body and the cat's soul, but the process doesn't turn the cat into a different type of animal essentially.
I never said the human soul is the direct result of evolution, nor did I say that a lower animal could generate a human soul in another, apart from any Divine Intervention. All I am saying is that accidental changes can result in substantial changes. If you want to say that God is involved in every substantial change, I would disagree with that, even though I do believe that God must have been involved in the course of human evolution. I certainly was not making a transhumanist argument, even though you misinterpreted it that way.
I made that analogical argument only to demonstrate that accidental changes can result in substantial changes. You say that "the process doesn't turn the cat into a different type of animal essentially," and I agree: chopping a cat in half turns the cat into a non-animal essentially.
Also, again, are you actually changing the substance of anything? Genuine question. The new substance (or new "historical substance" -- more on that later) never had a substance before: it never had the substance of its parents at any point in its existence, because from the beginning of its existence, it is, in evolutionary understanding, a different substance.
Am I misunderstanding you? So far I've understood what you mean as: accidental changes cannot cause substantial changes. Perhaps you're trying to say that, although accidental changes can separate the soul from the body, they cannot cause a new soul in a new body?
I tentatively agree. I could be completely wrong about this, but God intervenes in the creation of every soul, correct? Not just human, but animal as well? Because biological systems cannot create non-biological realities. So then it seems that the biological-accidental changes merely accompany substantial changes, and I'd say that this is true regardless of whether or not you accept evolution, because this happens in the conception of every animal: sperm and egg are essentially and substantially different from the creature which is conceived by their union. There's already a substantial change which is caused by (or perhaps accompanies) the accidental change.
Also, here's something I'm still working out, and maybe you have some insight into this. Considering the case of one species of dog generating another species of dog in two individuals' offspring: accidental changes in the chromosomes of the sperm of one dog and the egg of another dog result in a "specially" different creature --- whether you want to say that it's substantial or not is up to you, because 1) that's entirely a gray area (biologically and experientially) and 2) "dogness" may be the true substance, and each species merely a "historical substance," or more broadly, all animals may have the same soul substantially (i.e., "animal soul," instead of "dog soul" VS "cat soul"), making all of these macroevolutionary events merely accidental, special, and historically-substantial. This latter option seems correct to me. I wouldn't say that elephants have an elephant soul, but that they have an animal soul.
Lastly, what do you mean "begin the process of separation"? Why begin? What concludes it? If you think Divine Intervention does: sure, I think that's a tenable position, and it's perfectly compatible with what I've just said. In fact, I already mentioned that.
@Jack I am sorry if I am not expressing my best but English is my second language.
The potential is given by God and he is also the one who actualizes that potential, he gave us the primordial matter (water/chaos/earth/abyss in Genesis, the singularity from quantum theory or a primordial condensed field of quantum fluctuation, how ever you want to call it), that's on the level of "first cause" bringing about creation, when God uses secondary causes to manifest that reality fractally in creation, he uses the matter available to actualize a God's created soul into a material reality, so the sperm and the egg of an animal are the material available to actualize the soul that God created, and that's fine, the difference in matter available will change the accidental aspect and tendencies when that soul materializes, but the change it's still at the accidental level, it's only materially but not essentially, the matter is the same that has always existed thus this has not "evolved" and the soul is created from eternity by God thus it can't "evolve" you can only see a difference in development by the number and kind of potential available in space and time, now if you call that "evolution" then we are both agreeing, but if you say that God creates a fish soul that is to be embodied in a specific matter so that we have an actual material living fish, and that his soul is to reproduce its kind (fish) by using the matter available in fish (to maintain that kind of animal) but then at some point God uses that material lineage to bring about souls of other animals then that understanding of "evolving" becomes problematic, at what point does a fish ends up becoming a Dog, is God gradually from eternity making souls different to the point that it changes the kind of animal after a period of time? Having different races of dogs is not the same as a dog turning into a horse some day after too much breading. Evolution is a philosophy that doesn't include revealed theology in the understanding of created things, once you integrate revelation and theology into the philosophy of evolution you must make the philosophy fit in the theological reality and not do the contrary, that's why Saint Thomas was never an "Aristotelian" but rather a baptizer of the philosophical language of Aristotle into revelation and the life of the Church. With evolution the same must happen, development of kinds of animals is not the same as evolution from one animal into another.
@Irod Jetson I'm not sure I follow, and I think that's my own shortcoming, you probably have a better grasp on English than I do.
I'll try to sort things out here. Tell me where I'm wrong or misrepresenting you, but I think I got your ideas down faithfully.
"he uses the matter available to actualize a [dog's] created soul into material reality"
Wouldn't it be vice-versa, because matter is in potency? Wouldn't it be the matter that is actualized by its form? Or is that what you're already saying?
"...the sperm and the egg of an animal..."
Okay, so you seem to establish here that there is a change occurring, but that it's accidental because it's only material change.
"The matter is the same that has always existed thus this has not 'evolved'..."
But evolution is a process of change, correct? Basically it's governed by random mutation, meaning change. And you said that the matter has changed. Evolution is a process of change.
"...the soul is created from eternity by God thus it can't 'evolve'..."
In the precise moment of a macroevolutionary event, i.e. speciation, no soul has changed. There is no soul which is changing in any step of evolution. If you hold to the position that each "kind" of animal (whether that means "species," "genus," "substance," or whatever else) has its own unique soul (e.g., "dolphin soul" VS "chimpanzee soul"), then the moment of speciation would be something like a wolf (