"That is why I ask ? rational thought/reasoning/abstract thought."
An interesting take on the question by brain surgeon Michael Egnor:
http://www.evolutionnews.org/2015/11/the_fundamental_2100661.htmlIt is important to understand the fundamental difference between humans and nonhuman animals. Nonhuman animals such as apes have material mental powers. By material I mean powers that are instantiated in the brain and wholly depend upon matter for their operation. These powers include sensation, perception, imagination (the ability to form mental images), memory (of perceptions and images), and appetite.
Nonhuman animals have a mental capacity to perceive and respond to particulars, which are specific material objects such as other animals, food, obstacles, and predators.
Human beings have mental powers that include the material mental powers of animals but in addition entail a profoundly different kind of thinking. Human beings think abstractly, and nonhuman animals do not. Human beings have the power to contemplate universals, which are concepts that have no material instantiation. Human beings think about mathematics, literature, art, language, justice, mercy, and an endless library of abstract concepts. Human beings are rational animals.
Human rationality is not merely a highly evolved kind of animal perception. Human rationality is qualitatively different -- ontologically different -- from animal perception. Human rationality is different because it is immaterial. Contemplation of universals cannot have material instantiation, because universals themselves are not material and cannot be instantiated in matter.
I stress here the difference between representation and instantiation. Representation is the map of a thing. Instantiation is the thing itself. Universals can be represented in matter -- the words I am writing in this post are representations of concepts -- but universals cannot be instantiated in matter. I cannot put the concepts themselves on a computer screen or on a piece of paper, nor can the concepts exist physically in my brain. Concepts, which are universals, are immaterial.
Nonhuman animals are purely material beings. They have no concepts. They experience hunger and pain. They don't contemplate the injustice of suffering.
A human being is material and immaterial -- a composite being.
