Try teaching calculus to your pet goldfish, or explaining evolution by natural selection to the next squirrel you encounter. Or better yet, dedicate Thanksgiving break to teaching your family dog the basic rules of logic.
It’s a foregone conclusion that you will fail. No matter how hard you try, animals just can’t understand calculus, natural selection, or logic. It’s not that it is hard to effectively communicate with them. They are just not wired to grasp some forms of human intellectual activity, even under the tutelage of the smartest humans for many years. If Darwin knew dog-speak and taught his favorite pet Huxley natural selection, Huxley would be no more knowledgeable than he was before. He simply wouldn’t understand any of it.
Intuitively, humans are smarter than other animals in very many diverse intellectual domains. We can think in the counterfactual, reason deductively, create and process language, represent numbers abstractly, reflect on prior experience, play games like chess, raise critical questions, formulate hypothesis and test them, apply knowledge across different domains and create fiction — all abilities zebrafish, quokkas and so on don’t possess. That our intellect is capable of such problem-solving mental gymnastics is termed ‘intelligence,’ and for decades, thinkers have tried to define and quantify it. Charles Spearman, for example, described the g-factor in 1904, a single number that measured human intelligence. The g-factor theory was later revised and a version of it, the Cattell-Horn-Carroll (CHC), is used for Intelligent Quotient (IQ) testing across the world today. Yet, others argue that intelligence is not so objective as to be measurable by a number. For example, researchers at the Machine Intelligence Research Institute (MIRI) report that “The term also comes loaded with connotations … Laypeople tend to see intelligence as correlated with being clever, creative, self-confident, socially competent, deliberate, analytically skilled, verbally skilled, efficient, energetic, correct, and careful, but as anticorrelated with being dishonest, apathetic and unreliable. Moreover, cultures vary with respect to the associations they make with intelligence.” Indeed, many definitions and theories of intelligence have been abused to justify social injustice; in the early 1900s, for example, psychologist Henry Goddard popularized the eugenics movement that later resulted in sterilization laws being passed against the poor in many states across the U.S.
However, it’s important to note we shouldn’t confuse intra-species intelligence with inter-species intelligence. Even though we have historically failed to provide an uncontroversial account of intelligence that captures differences within humans, there is no denying humans are gifted with fundamental intellectual abilities our less privileged faunal peers lack. “We should not confuse Spearman’s g with human general intelligence, our capacity to handle a wide range of cognitive tasks incomprehensible to other species,” asserts Eliezer Yudkowsky of the MIRI. “General intelligence is a between-species difference, a complex adaptation, and a human universal found in all known cultures.” In other words, we are no longer talking about the difference between individual humans, but a difference in intelligence between entire species. The smartest frog can’t compete with an illiterate human when it comes to solving complex problems. “There is something about humans that let us set our footprints on the Moon,” Yudkowsky concludes.
But what is this something? What neural facet do we point to and exclaim: “it is that property which enables humans to grasp calculus?!” One possible answer is the speed of neurons and the rate at which they fire. The idea is that the faster nerves in the brain communicate, the more the information processed and hence, the better the intellectual ability — humans, then, possess complex reasoning faculties because our nerves just fire more frequently and have greater throughput. But surely such a stipulation cannot be right! A frog thinking twice as fast is still just a frog: it might accomplish twice as much as any other frog in the same amount of time, but the nature of its thoughts themselves, the possible number of different things it can think about, are still constrained; they are limited by what a frog’s brain can conceive of. If we pump steroids into a frog’s brain, its thoughts might race, but that doesn’t mean they will be somehow better, or of higher quality.
Nor can a qualitative improvement be effected by increasing the mind’s memory capacities. If increasing the maximum amount of information something could hold made it smarter, computers with massive storage space would be the most intelligent species ever; and surely this is an unacceptable implication. Often, bigger brain size is suggested as another candidate property to explain the intellectual prowess enjoyed by human minds. But clearly, brain size is not all that counts: elephants have much bigger brains than us but are nonetheless incapable of grasping math. What explains our intellectual prowess, according to Yudkowsky, is that the human brain is “different in kind” compared to that of animals. There’s something unique about our cognitive architecture, the way our brain is structured, that gives us to the ability to think abstractly and reason deductively, among others. Prominent philosopher Nick Bostrom calls this “difference in kind.” The human intellect is then qualitatively superior to that of other animals.
While Bostrom does not delve into what gives rise to specific faculties like language, cognitive science fills that gap for us. In the 1980s, neuroscientists built on Noam Chomsky’s idea of language acquisition to propose a modular model of the mind. This view contends that each of our intellectual abilities, such as deductive reasoning or thinking in the counterfactual, has evolved by natural selection and exists encapsulated into a specific cognitive module of our mind. Our faculty of language, for example, is brought about by the presence of language module and mathematical reasoning by the presence of the mathematical module. So when we talk about a qualitatively superior intellect, we mean that humans possess a set of problem-solving faculties contained within and determined by modules that animals lack.
While defining intelligence by a marriage of philosophy and cognitive science may not be perfect either, our framework provides a sturdy enough base to inquire: can we possibly create intelligent beings? This question is the holy grail of Artificial Intelligence (AI) research today, as scientists attempt to mathematically model human intelligence. It is a dramatically different question to ask whether we can create something as smart as a goldfish than something as smart as a human. If the former is true, we might question the need for pets; but if the latter turns out to be true as well, then we will begin questioning the importance of human existence altogether.