I would not have returned to the Faith as an adult were it not for discovering Aquinas' proofs of God, and I would not have come to Aquinas' proofs were it not for the Thomistic popularizer and reinvigorator Edward Feser. Accordingly, I owe Feser an incalculable debt.
Feser has feuded in print with Orthodox theologian David Bentley Hart, whom I also esteem for his splendid contributions to contemporary theology.
Their most recent slapfight--here, here, here, and here--concerns whether animals go to Heaven.
Besides a general disdain for (a caricature of) neo-Thomist manualism, Hart's thrusts attack the Thomist point that animals do not go to Heaven because their souls are not immaterial.
This point runs roughly as follows:
The soul, for a hylemorphist (i.e., an Aristotelian who believes that matter is structured by form) is the form of the body--the organization of its faculties.
The form of a rubber ball is, inter alia, its sphericity.
The form of a plant is its vegetative soul, the way that its matter is organized and informed unto nutrition, growth, and reproduction.
The form of an animal is its sensitive soul, which includes all the vegetative functions, but also informs animal functions of sensation, locomotion, appetition, emotion, and imagination.
The form of a human is his or her rational soul, which includes all the animal (and thus all the vegetative) functions, but also informs the human function of reason.
Now, modern science will confirm Aristotle's and Aquinas' view that vegetative and sensitive faculties are entirely embodied: they work in and through matter, and without matter, they do not work.
Reason is different. As the contemporary Thomist James Ross has argued in Immaterial Aspects of Thought (one of the most important readings in my own intellectual development as a Thomist and indeed as a Christian), reason incorporates a degree of abstraction and precision that the material, of its nature, cannot entirely embody.
Because reason is immaterial, the rational soul which instantiates it must, Aquinas rightly reasoned, be immaterial, too, as the vegetative and animal souls are not.
Now, animals have imagination and emotion, but they do not reason. They can be taught to communicate, but they do not make logical inferences or engage in mathematical theorization. An animal's mind is entirely exhausted by the hylemorphic form/matter compound of its brain, with no "naked form," no solely immaterial aspect, left over.
Thus, reasons the Thomist, dogs don't go to heaven. (Or cats to hell.) They cannot: Heaven and Hell are immaterial realities, and a dog has no immaterial soul.
Thus the Thomist, and so thus Feser. Hart is outraged at this slight to our animal brethren, and cites the Bible ("the lion shall lay down with the lamb," etc.) against it. Hart reminds us that the Kingdom of God will involve the restoration of all Creation. And it indeed it shall. But.
The feud has gone on for some time, and neither Feser nor Hart has drawn what seems to me to be the crucial distinction between Heaven and the General Resurrection.
When you die, we may hope that you go to Heaven. There, you will exist immaterially, as Aquinas teaches. But at the end of history, all the dead shall be raised. The sheep shall be separated from the goats. The saints shall live in glorified resurrection bodies in the New Jerusalem, and the damned shall burn: both the joy of the saints and the agonies of the damned shall be embodied, somehow--real pleasure, real burning.
There will be no dogs in Heaven, because there cannot be. But will there be dogs, will there be lions and lambs, in the general resurrection? Well, why not?
Just as the glorified body of the Risen Lord and of His Mother assumed bodily into Heaven (in a way that dogs very much are not) is not the corruptible, agonized and agonizing body we bear today, so the resurrected lion and lamb need not dwell in ichneumonidaean agony anymore.
In sum, I think Feser and Hart, two heroes of mine, are simply arguing past each other. Feser is right, with Aquinas, to affirm that there are no dogs in Heaven. Hart is right to affirm, with the Fathers, that there may indeed be animals in the Kingdom. But the Kingdom, in its fullness, is not the rest of the righteous in Heaven, but the glory of the saints in the general resurrection after Doomsday.