No essence, no unchanging core
University Distinguished Professor of Psychology, Northeastern University; Research Scientist and Neuroscientist, Massachusetts General Hospital/Harvard Medical School
Essentialist Views of the Mind
Essentialist thinking is the belief that familiar categories—dogs and cats, space and time, emotions and thoughts—each have an underlying essence that makes them what they are. This belief is a key barrier to scientific understanding and progress. In pre-Darwinian biology, for example, scholars believed each species had an underlying essence or physical type, and variation was considered error. Darwin challenged this essentialist view, observing that a species is a conceptual category containing a population of varied individuals, not erroneous variations on one ideal individual. Even as Darwin's ideas became accepted, essentialism held fast, as biologists declared that genes are the essence of all living things, fully accounting for Darwin's variation. Nowadays we know that gene expression is regulated by the environment, a discovery that—after much debate—prompted a paradigm shift in biology.
In physics, before Einstein, scientists thought of space and time as separate physical quantities. Einstein refuted that distinction, unifying space and time and showing that they are relative to the perceiver. Even so, essentialist thinking is still seen every time an undergraduate asks, "If the universe is expanding, what is it expanding into?"
In my field of psychology, essentialist thought still runs rampant. Plenty of psychologists, for example, define emotions as behaviors (e.g., a rat freezes in fear, or attacks in anger), each triggered automatically by its own circuit, so that the circuit for the behavior (freezing, attacking) is the circuit for the emotion (fear, anger). When other scientists showed that, in fact, rats have varied behaviors in fear-evoking situations—sometimes freezing, but other times running away or even attacking—this inconsistency was "solved" by redefining fear to have multiple types, each with its own essence. This technique of creating ever finer categories, each with its own biological essence, is considered scientific progress, rather than abandoning essentialism as Darwin and Einstein did. Fortunately, other approaches to emotion have arisen that do not require essences. Psychological construction, for example, considers an emotion like fear or anger to be a category with diverse instances just as Darwin did with species.
Essentialism can also be seen in studies that scan the human brain, trying to locate the brain tissue that is dedicated to each emotion. At first, scientists assumed that each emotion could be localized to a specific brain region (e.g., fear occurs in the amygdala), but they found that each region is active for a variety of emotions, more than one would expect by chance. Since then, scientists have been searching for the brain essence of each emotion in dedicated brain networks, and in probabilistic patterns across the brain, always with the assumption that each emotion has an essence to be found, rather than abandoning essentialism.
The fact that different brain regions and networks show increased activity during different emotions is not a problem just for emotion research. They also show increased activation during other mental activities such as cognitions and perceptions, and have been implicated in mental illnesses from depression to schizophrenia to autism. This lack of specificity has led to claims (in news stories, blogs, and popular books) that we have learned nothing from brain imaging experiments. This seeming failure is actually a success. The data are screaming out that essentialism is wrong: individual brain regions, circuits, networks and even neurons are not single-purpose. The data are pointing to a new model of how the brain constructs the mind. Scientists understand data through the lens of their assumptions, however. Until these assumptions change, scientific progress will be limited.
Some topics in psychology have advanced beyond essentialist views. Memory, for example, was once thought to be a single process, and later was split into distinct subtypes like semantic memory and episodic memory. Memories are now considered to be constructed within the brain's functional architecture and not to reside in specific brain tissue. One hopes that other areas of psychology and neuroscience will soon follow suit. For example, cognition and emotion are still considered separate processes in the mind and brain, but there is growing evidence that the brain does not respect this division. This means every psychological theory in which emotions and cognitions battle each other, or in which cognitions regulate emotions, is wrong.
Ridding science of essentialism is easier said than done. Consider the simplicity of this essentialist statement from the past: "Gene X causes cancer." It sounds plausible and takes little effort to understand. Compare this to a more recent explanation: "A given individual in a given situation, who interprets that situation as stressful, may experience a change in his sympathetic nervous system that encourages certain genes to be expressed, making him vulnerable to cancer." The latter explanation is more complicated, but more realistic. Most natural phenomena do not have a single root cause. Sciences that are still steeped in essentialism need a better model of cause and effect, new experimental methods, and new statistical procedures to counter essentialist thinking.
This discussion is more than a bunch of metaphysical musings. Adherence to essentialism has serious, practical impacts on national security, the legal system, treatment of mental illness, the toxic effects of stress on physical illness... the list goes on. Essentialism leads to simplistic "single cause" thinking when the world is a complex place. Research suggests that children are born essentialists (what irony!) and must learn to overcome it. It's time for all scientists to overcome it as well.
Evolutionary Biologist; Emeritus Professor of the Public Understanding of Science, Oxford; Author, The Greatest Show on Earth, The Magic of Reality
Essentialism—what I’ve called "the tyranny of the discontinuous mind"—stems from Plato, with his characteristically Greek geometer’s view of things. For Plato, a circle, or a right triangle, were ideal forms, definable mathematically but never realised in practice. A circle drawn in the sand was an imperfect approximation to the ideal Platonic circle hanging in some abstract space. That works for geometric shapes like circles, but essentialism has been applied to living things and Ernst Mayr blamed this for humanity’s late discovery of evolution—as late as the nineteenth century. If, like Aristotle, you treat all flesh-and-blood rabbits as imperfect approximations to an ideal Platonic rabbit, it won’t occur to you that rabbits might have evolved from a non-rabbit ancestor, and might evolve into a non-rabbit descendant. If you think, following the dictionary definition of essentialism, that theessence of rabbitness is "prior to" the existence of rabbits (whatever "prior to" might mean, and that’s a nonsense in itself) evolution is not an idea that will spring readily to your mind, and you may resist when somebody else suggests it.
Paleontologists will argue passionately about whether a particular fossil is, say, Australopithecus or Homo. But any evolutionist knows there must have existed individuals who were exactly intermediate. It’s essentialist folly to insist on the necessity of shoehorning your fossil into one genus or the other. There never was an Australopithecus mother who gave birth to a Homo child, for every child ever born belonged to the same species as its mother. The whole system of labelling species with discontinuous names is geared to a time slice, the present, in which ancestors have been conveniently expunged from our awareness (and "ring species" tactfully ignored). If by some miracle every ancestor were preserved as a fossil, discontinuous naming would be impossible. Creationists are misguidedly fond of citing "gaps" as embarrassing for evolutionists, but gaps are a fortuitous boon for taxonomists who, with good reason, want to give species discrete names. Quarrelling about whether a fossil is "really" Australopithecus or Homo is like quarrelling over whether George should be called "tall". He’s five foot ten, doesn’t that tell you what you need to know?
Essentialism rears its ugly head in racial terminology. The majority of "African Americans" are of mixed race. Yet so entrenched is our essentialist mind-set, American official forms require everyone to tick one race/ethnicity box or another: no room for intermediates. A different but also pernicious point is that a person will be called "African American" even if only, say, one of his eight great grandparents was of African descent. As Lionel Tiger put it to me, we have here a reprehensible "contamination metaphor." But I mainly want to call attention to our society’s essentialist determination to dragoon a person into one discrete category or another. We seem ill-equipped to deal mentally with a continuous spectrum of intermediates. We are still infected with the plague of Plato’s essentialism.
Moral controversies such as those over abortion and euthanasia are riddled with the same infection. At what point is a brain-dead accident-victim defined as "dead"? At what moment during development does an embryo become a "person"? Only a mind infected with essentialism would ask such questions. An embryo develops gradually from single-celled zygote to newborn baby, and there’s no one instant when "personhood" should be deemed to have arrived. The world is divided into those who get this truth and those who wail, "But there has to be some moment when the fetus becomes human." No, there really doesn’t, any more than there has to be a day when a middle aged person becomes old. It would be better—though still not ideal—to say the embryo goes through stages of being a quarter human, half human, three quarters human . . . The essentialist mind will recoil from such language and accuse me of all manner of horrors for denying the essence of humanness.
Evolution too, like embryonic development, is gradual. Every one of our ancestors, back to the common root we share with chimpanzees and beyond, belonged to the same species as its own parents and its own children. And likewise for the ancestors of a chimpanzee, back to the same shared progenitor. We are linked to modern chimpanzees by a V-shaped chain of individuals who once lived and breathed and reproduced, each link in the chain being a member of the same species as its neighbours in the chain, no matter that taxonomists insist on dividing them at convenient points and thrusting discontinuous labels upon them. If all the intermediates, down both forks of the V from the shared ancestor, had happened to survive, moralists would have to abandon their essentialist, "speciesist" habit of placing Homo sapiens on a sacred plinth, infinitely separate from all other species. Abortion would no more be "murder" than killing a chimpanzee—or, by extension, any animal. Indeed an early-stage human embryo, with no nervous system and presumably lacking pain and fear, might defensibly be afforded less moral protection than an adult pig, which is clearly well equipped to suffer. Our essentialist urge toward rigid definitions of "human" (in debates over abortion and animal rights) and "alive" (in debates over euthanasia and end-of-life decisions) makes no sense in the light of evolution and other gradualistic phenomena.
We define a poverty "line": you are either "above" or "below" it. But poverty is a continuum. Why not say, in dollar-equivalents, how poor you actually are? The preposterous Electoral College system in US presidential elections is another, and especially grievous, manifestation of essentialist thinking. Florida must go either wholly Republican or wholly Democrat—all 25 Electoral College votes—even though the popular vote is a dead heat. But states should not be seen as essentially red or blue: they are mixtures in various proportions.
You can surely think of many other examples of "the dead hand of Plato"—essentialism. It is scientifically confused and morally pernicious. It needs to be retired.