When the question of how human beings are different from other animals comes up, scientists begin to display a disturbing handicap in answering it. The theory of evolution, whatever else might be said about it, seems to constrain their answers to ones of mere differences of degree.
Humans, they say, are more this way or more that way than animals. They are more intelligent, more social, more moral, more whatever than animals. If the difference between humans and animals is solely due to biological development, then it must be this way. Their common origin allows only for differences in degree, but never in differences of kind.
Strictly interpreted, evolution holds that human traits are nothing more than highly developed animal traits. There cannot be something that humans have that animals do not have at all and have never had. That would destroy the whole thesis of evolutionary development.
Kevin Laland argues, in his recent Scientific American article “What Made Us Unique," that “our ability to think, learn, communicate and control our environment makes humanity genuinely different from all other animals." He is not saying that humans do these things and animals don't. He is merely saying that we do these things--think, learn, communicate, and control our environment--better than animals.
Michael Tomasello, author of the recent book Becoming Human, does the same thing. For him it is "mutual awareness," "cooperative thinking," "shared intentionality," that mark the difference between humans and apes--our closest evolutionary cousins. But again, these are not things that apes don't do at all, but only things they don't do as well as we do.
Maybe some day, scientists will evolve into philosophers. Only then will they be able to tell what the real difference between animals and humans is--a difference that marks humans out as unique, not just more highly developed.
Is there something that uniquely characterizes humans that makes them entirely and essentially different from animals?
In his book A Guide for the Perplexed, E. F. Schumacher uses concepts employed by philosophers such as Aristotle, Thomas Aquinas, and Jacques Maritain to explain how each kind of thing in the world differs from others. Minerals are the most basic kinds of things. But when you add life to them, they become organisms. Organisms, in turn, become animals by the addition of awareness:
If m = mineral, x = life, and y = awareness, then we get:
m = mineral
m + x = plant
m + x + y = animal
Each one of these differences marks out a kind of thing fundamentally different from other kinds.
But what about humans? Humans are made up of minerals, are living, and are aware. But unlike animals, they have self-awareness. They not only are conscious, they are conscious of their consciousness; they not only think, but think about the fact that they think. Self-consciousness is something humans have and animals do not have at all, and it is the basis for the ability to think about the True, the Good, and the Beautiful.
This is the real difference between humans and animals, but it's hard to explain how this self-awareness came about through pure biological development, which is probably the reason that scientists talk about it so little.