Contents:
I. The problem of species
II. Essential acts
III. The human quality
IV. What about humans who are stupider than animals?
Traditionally, people have believed that the world is full of qualitatively different kinds of things; that is, there are a multitude of distinct species. In the realm of living things, there was seen to be a vast gulf between plants and animals, and between irrational animals and humans. These categories were based on what were seen as the characteristic activities of each type of organism. Plants do things like absorb nutrients and grow. Animals do “vegetative” things like this too, but they also sense their environment and move. Humans do both vegetative and animal activities, but we also engage in abstract thought. Of course, it was also generally believed that there are many different species within the plant and animal kingdoms as well.
Since Linnaeus, modern biologists have put far more thought and precision into taxonomy than the ancients ever did. Ironically, the farther these efforts have gone, the more skeptical moderns have become over whether the thing can really be done in a non-arbitrary way at all. First, as more species become known, the separation between them gets smaller. It becomes more difficult to say exactly where one species ends and another begins. Two equally reasonable definitions might give slightly different answers. Even if intermediates between clearly distinct species don’t exist now, oftentimes they did in the past, and we have fossils to prove it. This leads one to ask, “Isn’t this whole exercise arbitrary to begin with? Shouldn’t we just think of a continuum of animal properties, with no qualitative jumps?” At the same time, some biologists seem to take a postmodernist’s delight in “problemetizing” the old categories, e.g. showing how plants can—in some sense—move or sense, or showing how animals can—in some sense—reason. I often see articles written for a popular audience making great claims for animal intelligence. Dogs use logic, apes communicate, etc. One very popular claim now is that animals have morality, by which is usually meant empathy and self-sacrifice, but sometimes also a sense of fairness. The implication of all this is clear, but in case you’re not clever enough to see it, these ardent biologists never miss a chance to point it out for you: human beings are qualitatively no different from animals. It’s not that we have some quality that other animals lack entirely; the differences are all just quantitative. Your capacity for abstract reason is, say, 40% higher than that of your pet dog; your moral sense is perhaps 20% more developed. What would it mean to accept that humans are not different from other animals? The conclusions we’re usually asked to draw are these: we should treat animals more like we treat humans, and we should think of humans more like the way we think of animals. The first consequence, of giving animals what we think of as “human” rights, would at worst be an inconvenience. The second consequence, however, would be devastating, as it would invalidate the idea that human beings have a unique calling, a qualitatively higher state of perfection, and therefore a unique dignity.
Throne and Altar 
[…] Human distinctiveness […]
I learned something useful from my favorite radio jocks last week: dignity is the capacity to take responsibility for one’s actions. It makes sense. Dignity is worthiness. It is, ontologically, a measure of a being’s ontological cash value, of its efficacious power; and power directed by a will informed by an intellect (as happens when one takes responsibility) is focused and efficacious in a way that mere physical power is not. The dignity of the soldier is greater than that of the grenade, for the soldier disposes of far more efficacy than the grenade, despite the fact that, as deployed in battle, he may dispose of less potential energy per unit time than the grenade.
Dogs clearly take some responsibility. My dog Rosie is capable of lying, and of shame at the way she has behaved. Otherwise, the utterance, “Bad dog!” would have zero meaning to her, or therefore to me. It would mean nothing intelligibly different than “Good dog!” or “Squirrel!” And, meaning nothing different to Rosie, none of these utterances of mine would affect her differently. But they do. She responds appropriately to my utterances, if not intelligently.
But this is very far from saying that she is equal in dignity to me. For, because I can comprehend my actions vis-a-vis the world far more completely than she, so I can take a more informed responsibility for my actions. The more comprehensive the information of my actions, the more efficacious they are, and the greater my dignity (and my liberty).
My dignity as a man, then, as different quantitatively from hers, is ipso facto different qualitatively, in just the same way that possessing $10 is qualitatively different from possessing $1,000,000.
The bottom line: a quantitative difference just is a qualitative difference; for quantity is a quality. Where the quantitative difference is trivial, it is negligible; where not, not. It all comes down to a judgement of importance. The difference of intelligence between me and Rosie puts us in different categories of things, just as the difference of mass between Jupiter and Sol puts them in different categories. Categories are porous, to be sure, so that taxonomies are bound upon close examination to look somewhat adventitious, in one way or another; but if categories were not real, there would be no membrane to have the pores, no way to arrive at the conclusion that the boundaries are somewhat arbitrary. You can’t say that things are close to each other, or similar, without implicitly admitting that they are truly and fundamentallyh and essentially different. Again, it all comes down to a judgement about how important those differences are.
[…] on human evolution actually is. Of course, this says nothing about what our position should be. I believe that speciation by natural selection is compatible with a realist position on forms (because […]
Wise and holy St. Thomas Aquinas once said the following in relation to why men walked upright:
“An upright stature was becoming to man for four reasons. First, because the senses are given to man, not only for the purpose of procuring the necessaries of life for which they are bestowed on other animals, but also for the purpose of knowledge. Hence, whereas the other animals take delight in the objects of the senses only as ordered to food and sex, man alone takes pleasure in the beauty of sensible objects for its own sake. Therefore, as the senses are situated chiefly in the face, other animals have the face turned to the ground, as it were for the purpose of seeking food and procuring a livelihood; but man has his face erect, in order that by the senses and chiefly by sight, which is more subtle and penetrates further into the differences of things, he may freely survey the sensible objects around him, both heavenly and earthly, so as to gather intelligible truth from all things.”
“Secondly, for the greater freedom of the acts of the interior powers; the brain, wherein these actions are, in a way, performed, not being low down, but lifted up above other parts of the body. Thirdly, because if man’s stature were prone to the ground he would need to use his hands as fore-feet, and thus their utility for other purposes would cease. Fourthly, because if man’s stature were prone to the ground and he used his hands as fore-feet, he would be obliged to take hold of his food with his mouth. Thus he would have a protruding mouth, with thick and hard lips, and also a hard tongue, so as to keep it from being hurt by exterior things, as we see in other animals. Moreover, such an attitude would quite hinder speech, which is reason’s proper operation.”
The differences are not only in mind, but in physical form.