The first step to knowledge is naming something, as if often said. So, what is "to think?" To me, thinking has a number of basic components. Foremost, I follow the logic of neuroscientist Antonio Damasio, who distinguishes two broad basic forms of consciousness: core consciousness and extended consciousness. Many animals display core consciousness: they feel; and they are aware that they are feeling. They know that they are cold, or hungry, or sad. But they live in the present, in the here and now. Extended consciousness employs the past and the future, too. The individual has a clear sense of "me" and "you," of "yesterday" and "tomorrow," of "when I was a child" and "when I'm old."
Higher mammals employ some manner of extended consciousness. Our closest relatives, for example, have a clear concept of the self. Koko the gorilla uses a version of American Sign Language to say, "Me, Koko." And common chimpanzees have a clear concept of the immediate future. When a group of chimps were first introduced to their new outdoor enclosure at the Arnhem Zoo, Holland, they rapidly examined it, almost inch by inch. They then waited until the last of their keepers had departed, wedged a long pole against the high wall, and marched single file up to freedom. Some even helped the less surefooted with their climbing. Nevertheless, it is vividly apparent that, as Damasio proposes in his book, The Feeling of What Happens, this extended consciousness attains its peak in humans. Will machines recall the past, and employ their experiences to think about the future. Perhaps.
But extended consciousness is not the whole of human thinking. Anthropologists use the term symbolic thinking to describe the human ability to arbitrarily bestow an abstract concept upon the concrete world. The classic example is the distinction between water and "holy water." To a chimp, the water sitting in a marble basin in a cathedral is just that, water; to a Catholic it is an entirely different thing, "holy." Likewise, the color black is black to any chimp, while it might connote death to you, or even the newest fashion. Will machines ever understand the meaning of a cross, a swastika, or democracy? I doubt it.
But if they did, would they be able to discuss these things?
There is no better example of symbolic thinking than the way we use our squeaks and hisses, barks and whines to produce human language. Take the word: "dog." English speaking peoples have arbitrarily bestowed the word "dog" upon this furry, smelly, tail-wagging creature. Even more remarkable, we humans easily break down the word "dog" into its meaningless component sounds, "d" "o" and "g," and then recombine these sounds (phonemes) to make new words with new arbitrary meanings, such as "g-o-d." Will machines ever break down their clicks and hisses into primary sounds or phonemes, then arbitrarily assign different combinations of these sounds to make different words, then designate arbitrary meanings to these words, then use these words to describe new abstract phenomena? I doubt it.
And what about emotion? Our emotions guide our thinking. Robots might come to recognize "unfairness," for example; but will they feel it. I doubt it. In fact, I recently had dinner with a well-known scientist who builds robots. Over dinner he told me that it takes a robot five hours to fold a towel.
I sing the human mind. Our brains contain over 100 billion nerve cells, many with up to 10,000 connections with their neighbors. This three–pound blob is the crowning achievement of life on Earth. Most anthropologists believe the modern human brain emerged by 200,000 years BP (before present); but all agree that by 40,000 years ago our forebears were making "art" and burying their dead, thus expressing some notion of the "afterlife." And today every healthy adult in every human society can easily break down words into their component sounds, remix these sounds in myriad different ways to make words, grasp the arbitrary meanings of these words, and comprehend abstract concepts such as friendship, sin, purity and wisdom.
I agree with William M. Kelly who said: "Man is a slow, sloppy and brilliant thinker; the machine is fast, accurate and stupid."