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  Coming In and Going Out

  Despite excited predictions that technological innovation will usher in artificial wombs and everlasting life, it is still true that every human being is born from the body of his or her mother and every human being dies. No one chooses to be born, and although some people decide to die, many of us would prefer not to. Beginnings and endings, life and death are not simple concepts. When “life” begins has long been a philosophical question as well as the subject of ferocious political debate. What constitutes “death” is also unclear, although once a corpse begins to putrefy, all doubt vanishes. Nevertheless, every mammal begins in maternal space. And yet, this obvious fact, that a fetus, something every person once was, is physically connected to its mother and cannot survive without her, has played a relatively small role in mainstream philosophical and scientific thought about what human beings are.

  Innumerable books have been written about why and how the idea of the autonomous, self-governing, free man who shapes his own destiny came about in the history of the West. Many of them are concerned with how historical ideas shaped the consciousness of whole populations and remain with us still and, further, whether the humanist ideal, generally understood to have started with the Renaissance (named, of course, after the fact) and culminated in the Enlightenment, is good or bad or a bit of both. Mostly, such books have little or no use for biology. Although it is assumed that biological realities exist—how could one be swayed by an idea without a mind and body to receive it?—the material intricacies of living things are often left out of the story.

  But biology, too, relies on concepts, concepts of life and death, of beginnings and endings, and of a creature’s borders. Skin forms a border covering a human being, who is made up of billions of cells. A bacterium, on the other hand, is a microscopic, usually single-celled organism that consumes nutrients, multiplies, and becomes a colony with its own morphology (form and structure) and movement. Science is about making good models and creating borders that divide nature into comprehensible bits, which can then be classified, named, and tested. Sometimes classifications and names lose their relevance and scientists adopt a model with new designations better suited to their needs. Distinguishing one thing from another is essential, however. Sometimes isolating a thing is difficult. Sometimes its borders are not obvious. It is interesting in this context to discover that scientists know little about the placenta, which has been variously described in recent years as poorly understood, underappreciated, and even as “the lost neuroendocrine organ.”1 Of course, when a person, thing, or bodily organ is assigned the status “unfairly ignored,” it usually serves as a flag to alert us to the fact that the times have changed. The placenta is a borderline organ between mother and fetus. It is a composite structure, sometimes described as a fetomaternal organ, because it develops from both the mother’s and the embryo’s tissues. It occupies a between space inside maternal space.

  The placenta delivers nutrients and oxygen to the fetus, disposes of its waste, gives it immune protection, produces the hormone progesterone, and contains two blood circulatory systems, one for the mother and one for the fetus. Its multiple functions are the reason one embryologist referred to it as “the third brain” in gestation.2 The human gut or enteric nervous system—stomach, esophagus, small intestine, and colon—has gained the moniker “the second brain,” so brains showing up in one part of the body or another, as it were, are currently in fashion. The placenta develops only in women and only in pregnant women, and it is a transient organ. When its job is over, it is expelled from a woman’s body after the baby is born. Hence the term “afterbirth.”

  Since the scientific revolution, “divide and conquer” has been a route to understanding, but much depends on the divisions that are made. I ran across an intriguing sentence in a medical school lecture, “Physiology of Normal Labor and Delivery”: “The mechanical steps the baby undergoes can be arbitrarily divided, and, clinically, they are usually broken down into six or eight steps for ease of discussion. It must be understood, however, that these are arbitrary distinctions in a natural continuum.”3 The physician tells us, albeit awkwardly, first that what happens to the infant in labor and birth consists of mechanical steps but then undermines his own statement by asserting that those same steps can be divided into arbitrary ones. If the mechanical steps are arbitrary and truly don’t reflect the natural continuum, which, as a continuum, resists the very idea of any and all “steps,” then the words “mechanical steps” are the wrong way to introduce the sentence. The “steps” are conveniences used to carve up an ongoing indivisible process, so it can be talked about more easily. It is not hard for a person to get lost in bad prose, but my sense is that the author’s language reveals not just his ambivalence about where to draw lines between one thing or “step” and another but his desire to make sure his medical students understand that there is a difference between the categories used in medicine and the dynamic processes to which they refer—in this case, labor and birth.

  Language counts, and language is continually generating metaphors. For example, how is a placenta like a third brain? Samuel Yen, who coined the phrase, argued for the placenta as a complex mediator between the mother’s brain and the immature fetal brain, a short-lived go-between brain with startlingly sophisticated capacities for regulating the fetal environment. The language used to describe what the placenta does include words used for “the first brain,” as well as for other bodily systems: “messages,” “signals,” “communication,” and “information.” It is not absurd to ask where the idea of “the mind” comes in to all this systemic signaling. Although it is odd to think of an organ like the placenta as something like a mind, it is less odd to think of it as something like a brain—another elaborate, hugely complicated, still not well understood physical organ. When the brain ceases to function, even when your heart is pumping and your lungs are working, doesn’t your mind go with it? Are you dead? Or does all “communication” of various kinds, all biological motion, have to stop before a person is truly dead and begins to decay?

  What significance, if any, does the fact that mammals gestate inside another body have for the mind? What does this biological reality have to do with how a mammal develops over time? We are born of someone, but we do not die in pairs. We die alone, although sometimes a spouse, partner, or friend quickly follows his or her beloved to the grave. The old expression for this phenomenon was “dying of grief.” Human beings come out of our mothers and into the world, and we go out from that same world when our bodies shut down in one way or another. Does a mind and the consciousness that accompanies it begin at birth and end at death? Where exactly is the mind located in the body? Is it only the brain that thinks or do other organs think in some way, too? What is thinking? Why are some contemporary scientists convinced that through artificial minds, death can be overcome, not in a heavenly paradise but here on earth? These are old questions without easy answers, but they take me back to the seventeenth century and to some of its famous and less famous philosophers who were hard at work trying to figure out what minds are and what they have to do with our bodies.

  Dressing Gowns, Triangles, Machines, Mind in Matter, and Giants

  Ever sinc
e my first reading of René Descartes’s Meditations almost forty years ago, I have retained a vision of the philosopher lying back in a soft chair, wearing a velvet brocade dressing gown and sleeping cap, with slippers on his feet and a pair of spectacles on his nose, which he may or may not have worn, but he made discoveries in optics, which probably explain their presence in my mental picture. He appears to me, not as a flesh-and-blood person, but as a drawing rather like the ones made two centuries later by “Phiz,” Dickens’s illustrator. This image of Descartes is a caricature, one that pops to mind whenever I think of radical doubt. In his First Meditation (1641), Descartes wonders if there is anything he can know for certain. Surely, he writes, he cannot doubt “I am here sitting by the fire, wearing a winter dressing gown, holding this paper in my hands.”4 The philosopher, however, is not at all certain that he is there by the fire. Hasn’t he had dreams of just this sort, he asks, dreams of sitting by the fire in his dressing gown, and felt sure of their reality? Like Plato before him, Descartes was suspicious of knowledge that arrived through his senses.

  After taking a position of absolute doubt about his own existence and everything in the world around him, he guides his reader through a series of arguments by which he reaches certainty, truths that have come to him through a process of purely rational thought. Descartes’s certainty has also been given a picture in my mind, one that comes from the philosopher himself: a triangle, the same geometric figure Plato used to argue for his theory of forms. My triangle is weightless, unmoving, and hangs in the air. No doubt, that is what I saw in my mind when I first encountered the philosopher’s triangle, which plays a part in his ontological argument for God’s existence. “When, for example, I imagine a triangle, even if perhaps no such figure exists, or has ever existed, anywhere outside my thought, there is still a determinate nature, or essence, or form of the triangle which is immutable and eternal, and not invented by me or dependent on my mind.”5 For Descartes, mathematics, logic, and metaphysics are universal, immutable, and therefore disembodied. The mind or soul has a priori or innate ideas, which are not its own products. One could say that for the seventeenth-century philosopher, reasoning and God are bound up together. Mathematics resides in a transcendent space, unsullied by the mortal, sensual body, the one that wears dressing gowns and warms its feet by the fire. In my mental catalogue of recurring images, I summon the triangle when I want to evoke an image of static, timeless, disembodied truth. The idea that number is truth is older than Descartes and older than Plato. In the fifth century B.C. the Pythagoreans taught that number rules the universe.

  Sensation and imagination do find a place in Descartes’s philosophy, but it is only with the aid of our minds that seeing, feeling, touching, tasting, smelling, hearing, and imagining create understanding. The body with its memories, imagination, and passions interacts with the mind, but the two are made of different stuff. The separation of psyche/soma remains a commonplace in contemporary culture. “It’s all in your mind” is convenient shorthand to tell a friend his problem is “psychological” or “mental.” A broken leg, on the other hand, is a “physical” problem, one that may require setting and a cast. But what are thoughts made of? And if they don’t come from our bodies, where do they come from? When I was a child, thoughts about thoughts sometimes arrived at moments when the world suddenly felt unreal to me and I felt unreal to myself. What if I am not Siri? What if I am a person inside another person’s dream? What if the world were a world inside another world inside another world? What are human beings really and how can we know what we are? How is it that we can talk to ourselves inside our own heads? What are words?

  For Descartes, Cogito ergo sum, I think therefore I am, can belong only to human beings. Animals do not think. They are creatures without souls and therefore are made of pure matter, mere machines. According to the philosopher, all matter has extension, which thoughts do not. Matter occupies space and is made up of tiny “corpuscles,” essential particles similar to atoms, but not atoms. Like many thinkers of his time, Descartes was influenced by the ancient atomism of Epicurus and Democritus, for whom the world was composed of atoms, hard bodies of matter moving in a void. Descartes had to distance himself from ancient atomism because it had no room for the Christian God or an eternal soul-mind, and he did not accept the idea of a void. In a letter to Father Mersenne in 1630, Descartes described his corpuscles: “But it is not necessary to imagine them to be like atoms nor as if they had a certain hardness. Imagine them to be like an extremely fluid and subtle substance.6 Unlike ancient atoms, corpuscles are soft. Atoms remain with us, of course, in another form, but it is interesting that the image of modern atoms, too, has changed shape since I was a schoolgirl looking at models of atoms with their neutrons and circling electrons that reminded me very much of the other model I studied: the solar system.

  Many thinkers continue to live with Descartes’s legacy. The questions he asked about the stuff we human beings are made of, our relation to the world, what is innate to us, what is acquired through sensory, lived experience, and whether there are immutable timeless truths continue to haunt Western culture. Most people intuitively think of thoughts as different from bodies. Over and over, in all kinds of writing, both academic and popular, the psychological and the physiological are split. Are they different? Or are they the same? How does a thought relate to neurons in the brain? Was the form of the triangle out there in the universe waiting for a person to discover it? There are people today who believe in the truth of the triangle, who defend the idea that logic and mathematics transcend the human mind, and others who do not.

  Thomas Hobbes, Descartes’s contemporary, championed a purely atomistic, materialistic, mechanical model of human beings and nature. We and the whole universe are made of the same natural atomic stuff and obey the same laws of motion, which means that the world comes to us only through our senses. Hobbes’s materialism proposed a first mover—God kicked the clanking machinery of nature into gear, but exactly what the deity was to Hobbes otherwise is unclear. For him, the human body was a machine, and all thought and sensation were machine-like motions of the brain. In chapter 5 of Leviathan, “Of Reason and Science,” Hobbes portrays human reason as a series of calculations: “In summe, in what matter soever there is place for addition and subtraction, there is also a place for Reason; and where these have no place, there Reason has nothing at all to do.”7 Unlike our inborn senses and memory or the prudence we gain from experience, reason comes to us by way of “industry,” the work of connecting one “Element, which are Names,” to another. Because these name elements are so vital to thought itself, Hobbes is adamant that the language we use should be “purged from ambiguity.”8 Metaphor is especially dangerous and apt to mislead the reasoning person into all manner of absurdity.

  Hobbes, like Descartes, was greatly influenced by Galileo. He took from the philosopher and scientist an admiration for geometry as a true method of modeling the natural world. Reason for Hobbes is a form of step-by-step calculation, by which one understands how one thing is related to the next through cause and effect, a relation that makes prediction possible:

  And whereas Sense and Memory are but knowledge of Fact, which is a thing past, and irrevocable; Science is the knowledge of Consequences, and dependence of one fact upon another . . . Because when we see how any thing comes about, upon what causes, and by what manner; when the like causes come into our power, we see how to make it produce the like effects.9

  Margaret Cavendish, Duchess of Newcastle, was exposed to the thought of Descartes and Hobbes because they belonged to the intellectual circle of her husband, William, and her brother-in-law Charles. Exiled Royalists in France, the duke and duchess took great interest in the debates that turned on nothing less than what human beings, animals, and the world are made of. The duchess met Descartes and knew Hobbes. The English philosopher refused to engage her in conversation or correspondence. Margaret Cavendish’s ideas were mostly ignored in her lifetime, but she publishe
d twenty-three books, which included plays, poems, fancies, a utopian fiction, The Blazing World, a biography of her husband, an autobiographical work, letters, and natural philosophy. In recent decades her voluminous writings have been reexamined in light of contemporary debates about mind and body. As her natural philosophy developed, Cavendish not only opposed Descartes’s dualism, his belief that mind and body are two different substances, she also rejected Hobbes’s mechanistic, atomistic theory and advocated a monistic organicist view (we are all material but not machine-like), although she distinguished between what she called “animate” and “inanimate” matter.

  Cavendish’s two kinds of matter helped her explain how rocks and people share the same material, how mind exists not as its own distinct substance but as part of the world. These two forms of matter, animate and inanimate, are not isolated from each other but are wholly blended together: “There is such a commixture of animate and inanimate matter, that no particle in nature can be conceived or imagined, which is not composed of animate matter, as well as of inanimate.”10 Her pan-organicism mingled with a form of panpsychism—that mind is not only part of human beings but part of everything in the universe. Panpsychism has had a long history, and many notable thinkers have subscribed to some version of it.11

  The question “What are human beings made of?” is still with us. For Cavendish, there was only material in the universe, but it was not built of particulate atoms and was not mechanistic. Its movement was not predetermined; it was not a machine. “Nature is a self-moving, and consequently self-living and self-knowing infinite body.”12 For Cavendish, human beings, other species, flowers, and vegetables were bound in a fundamental and strikingly fluid dynamic unity:

  Neither can I perceive that man is a Monopoler of all Reason, or Animals of all Sense, but that Sense and Reason are in other Creatures as well as in Man and Animals; for example, Drugs, as Vegetables and Minerals, although they cannot slice, pound or infuse, as man can, yet they can work upon man more subtilly, wisely, and as sensibly either by purging, vomiting, spitting, or any other way, as man by mincing, pounding and infusing them, and Vegetables will wisely nourish Men, as Men can nourish Vegetables.13