It is popular in some circles to claim that people are essentially different from animals. This would imply that there is some special property possessed by humans alone. Once intelligence was thought to play this role, but investigations into animal intelligence have shown that animals have the same kind of mental capabilities as we do, just in a more limited form. And because intelligence appears to be an ability that can be possessed to greater or lesser degrees it doesn’t make sense to draw a line on the scale and assert that being on one side is something intrinsically special. The next candidate for what could possibly make people special is consciousness. Of course if you believe in a dualist position then you may feel perfectly confident in asserting that animals are missing the necessary Cartesian ego, but unfortunately for dualists it is equally possible to deny that other people have the necessary Cartesian egos (see here). Fortunately for us we are materialists. However, because we are materialists we can no longer rely on consciousness as something that distinguishes people from animals. Consciousness is just a property of certain systems, and as best we can tell from their behavior it seems possible that many animals are just such conscious systems. Nagel argued that to be conscious there must be something “it is to be like”, and it certainly seems plausible that there is something it is to be like a dog or cat. And of course with consciousness comes self-consciousness, in perhaps a less complex form than the self-consciousness we posses, but that is simply a product of our greater intelligence, and since we have already ruled out intelligence as dividing people from animals we must conclude that the exact form of our conscious experience doesn’t either. Finally, some argue that animals are mechanical, that their perceptions lead directly to behavior while ours do not, or that animals don’t possess concepts and can’t reason abstractly while people can. Both these claims are simply false, as studies of animals have shown that they do have internal psychological states that influence their behavior, often more than their perceptions do, and that they do conceptualize their world, to a limited extent (again because of their limited intelligence).
Why then do humans and the rest of the animals seem so different, given that there are no essential differences between us? Good question. After all humans have mastered sciences, written languages, arts, and so forth, while animals haven’t even made a start in these areas. To explain this let me first discuss water. Water, like most substances, is a liquid in one temperature range and a solid in another. And, even though as water molecules are cooled down they undergo no radical changes, the transition from liquid to solid happens with almost no intermediate stages, a phenomenon called a phase change. Similarly there is nothing essentially different between individual animals and individual humans, besides a difference in physical form and intelligence, but groups of non-humans and groups of humans have completely different properties. My proposal is that, like water, a group undergoes a phase change when the members have a sufficiently high average intelligence. On one side of the intelligence “freezing point” we have only the primitive groups that animals are found in, and on the other side we have complex human societies. The essential difference between these two kinds of groups is that humans have the intelligence required to understand information communicated to them, improve upon it, and then pass it along to someone else. This ability, which is itself simply the product of a sufficiently high intelligence, means that the information in a human society has the potential to “blow up” while that in animal societies does not. And indeed many of the differences between a human society, even the most primitive, and groups of other animals can be seen as a result of their vastly increased informational content. (For example, elaborate traditions that are expanded slightly with each generation.)
So what is the difference between individual people and animals? Essentially nothing, our differences are only a matter of degree. Human groups and animal groups, however, are essentially different, human societies handle information in a way that sets them far apart from groups of animals that are only slightly less intelligent than us. Does this make humans special? Only if you consider the H2O molecules in liquid water as being essentially different from those in ice.