What we did initially was to focus on what we saw as an essential property of our system—the power plant—and let that drive our discussion of sameness. This is akin to the process of making analogies: finding the similarities between two situations or mental representations and then using the similarities as a reason for inferring something new about one of the two entities.[72] Because both locomotives and automobiles are the same in terms of using diesel-fired internal combustion, we infer, by analogy, that they must have other similarities. And they do, depending on how we construe the categories for those other similarities.
Because the mental categories that we create are hierarchical and, if we are careful, mutually exclusive at a given level in the hierarchy, we can always find similarities among any and all physical things.[73] This kind of general sameness—for example, all physical things are similar because they are composed of matter—is what a philosopher would call “trivial.” Trivial inferences are either tautological (as here, when we define the thing of interest by merely restating the thing) or self-evident.
Lesson learned: whenever we talk about two things being the “same” or “different,” we need to first (1) define our terms and agree on those definitions, (2) define and identify our categories of comparison, and then (3) keep the discussion focused on those terms and categories.
Let’s try this out. By analogy and category expansion we can always argue that a brain is the same thing as a computer. However, can we find some nontrivial category of in-the-same-way-as, some functional equivalence between brains and computers? Yes, we can. Both brains and computers can use, at least some of the time, explicit algorithmic steps to calculate. By “calculate” here I mean, as we were talking about with a Turing-computable algorithm, steps of instructions that can be explained with symbols such as numbers or words. In addition, those instructions, if followed exactly, will always produce the same result if you start with the same inputs. Thus, in the category of “calculators,” brains and computers can perform mathematical calculations like “1 + 1 = 2.” With input from external sensors brains and computers can perform more complex calculations like “when will that football hit my head.”
Now you might argue that calculation is a trivial, self-evident similarity because humans created digital calculators, what we call “computers,” with their brains. Thus, you’d argue, we merely figured out how our brains worked and then made machines do the same thing. Precisely. But far from being trivial, I’d argue, this is an example of what philosophers of mind and artificial intelligence call “functionalism,” the similarity of how two different entities operate.[74] Under functionalism, “the mind” of humans contains a whole library of innate and learned functions that can be carried out by any number of physical mechanisms, including a brain and a computer.[75] From this perspective, the brain is a computer and the computer is a brain in the sense that both can work the same way—manipulating symbols—at least some of the time and for at least some kinds of operations.
Emotional response: any damn fool knows that a brain and a computer are different! Just look at them. One is grown out of cells, is wet, and is possessed by animals. The other is built by human animals out of silicon, metal, and plastic and it sits on my desk. They may share some functions—like calculation and memory—but I don’t see my computer functioning as a food-seeking, reproducing, and evolving creature. Hmmm … or do I? Maybe my computer just needs a body the same way that my brain does.
Confused? That’s a good sign, even if you feel bad about the situation. Confusion means that your assumptions are being challenged and that you are open, probably against your will, to learning something new. But confusion is a vulnerable state. My students in “Introduction to Cognitive Science” hate confusion and the vulnerability it reveals. They came to college for information, not questions, damn it! How can they show me how smart they are if they don’t have facts to learn, apply, and brandish? My job, they tell me, is to illuminate, not obfuscate.
Here’s part of the problem: functionalism complicates the landscape, removing minds and intelligence from the sole province of humans. With the mind-blowing idea that intelligence might be found and built in nonhuman entities, most students seek comfort food. From their menu they order neuroscience: “Look,” they say, “if we start from a neuroscientific perspective, we can build up from neurotransmitters, synapses, and neural circuits to an understanding of how brains, and human brains in particular, work. And once we know how human brains work,” goes their logic, “we can understand what intelligence really is!”
Okay, folks. Let’s see how far we get. Let’s embrace the powerful neurocentric and reductionistic view (I’m not being sarcastic—it is powerful) and build a brain from the ground up. This is science, after all, and as we saw in Chapter 3 with the engineers’ secret code, if we understand it, then we should be able to build it.
“But first,” asks the evil professor, “what is the ‘it’ that you want to build?” Is “it” the brain? Which brain? If you mean an “animal brain,” then, which group of animals? If you mean “human,” then I have to ask, “What anatomical structures are you including?” What if our understanding of the human brain, at any structural or functional level, is incomplete? (Which it is.) Do you want to start instead with the more inclusive “central nervous system,” which includes the spinal cord and its anterior extensions? Would you want to include the so-called peripheral nervous system? What about the sensory systems, including the proprioceptive systems in our joints and muscles? And hormonal systems, including the glands that make chemicals that alter brain function? And what about the circulatory system, which delivers those chemicals, including glucose and oxygen, to the nervous system? Do we include the lungs, which provide the oxygen, and the digestive system, including the liver, that provides the glucose?
Have I left anything out? No, and that’s a blessing and curse. By admitting that that brain, however we define it and whatever structural context we put it in, is dependent on nonbrain stuff, we’ve just described an embodied-brain, a brain integrated into the whole critter. Can we dissect out just the brain? Yes. But as Phaedrus pointed out in Zen and the Art of Motorcycle Maintenance,[76] when you cut any system apart with your intellectual scalpel—when you analyze—you do so arbitrarily. In our case, when we look for nice, clean, predefined borders between “brain” and “body,” there simply are none. The best we can do is acknowledge what analysis does and make it clear to ourselves and to others that there are an infinite number of ways to skin Weiner’s cat.[77]
One place to apply the analytical knife is between anatomy and physiology. From the anatomical (structural) perspective, the brain is what it’s made of. If we start in the most general way possible, we need an anatomical definition of “brain” that works for all animals. Richard and Gary Brusca, expert invertebrate zoologists, state, “[The] central nervous system is made up of an anteriorly located neuronal mass (ganglion) from which arise one or more longitudinal nerve cords.”[78] This anterior (= toward the front of the animal) mass of neurons is called either a “brain” or an “anterior ganglion,” depending on whom you are speaking to.
The brain of vertebrates, suggests Georg Striedter, associate professor of neurobiology and behavior at the University of California at Irvine, can be defined in three distinct ways anatomically: by region, by cells, and by molecules.[79] By region, Striedter says, “All adult vertebrate brains are divisible into telencephalon, diencephalon, mesencephalon, and rhombencephalon.” By cells, the brains of jawed vertebrates possess the cells of the broad types known as neurons and glia. By molecules, Streidter explains that the brains of both vertebrates and invertebrates are characterized by the presence of the same neurotransmitters (you’ll hear more about what those do later), including glutamate, GABA, acetylcholine, dopamine, noradrenaline, and serotonin. For the anthropocentric, Striedter points out that the anatomy of the human brain is different from other vertebrate brains by degree: it is more than four or five times larger than expected for a mammal of its body mass (a metric called “relative brain size”) and has the most layers of neurons in the cortex (a division of the telencephalon).
72
Dedre Gentner and B. Bowdle “Metaphor as Structure-Mapping,” in
74
A good introduction to functionalism and other issues in the philosophy of mind can be found in K. T. Maslin,
75
Many different flavors of functionalism exist. “Artificial Intelligence” functionalism, for example, attends to the creation of the same kind of intelligence in vertebrates, computers, and robots. I think you can also make a case for what I call Biological Functionalism: when independent evolutionary events converge on similar functional designs. For example, the brains of birds and mammals are very different in terms of how the different parts have evolved compared to their hypothetical common ancestor. But some birds, like crows and parrots, manage to have brains that allow them to make and use tools and language. These convergent abilities show that some birds and mammals possess the same kind of intelligence (= similar function) that is created by different structures. For a great review of the functional similarities and structural differences of birds and mammals, I recommend the following paper: Ann B. Butler and Rodney M. J. Cotterill, “Mammalian and Avian Neuroanatomy and the Question of Consciousness in Birds”
76
Robert M. Pirsig,
77
Yes, this is the same conceptual cat that Norbert Weiner used, as we spoke of in Chapter 1, to assert problems with modeling: the best model of a cat is a cat. Interesting, is it not, that Weiner’s cat surfaces here as a warning about studying the cat itself? The cat has Weiner’s tongue.
78
Robert C. Brusca and Gary J. Brusca,
79
Georg F. Striedter,