Why do rocks fall? Before Isaac Newton introduced his revolutionary law of gravity in 1687, many natural scientists and philosophers thought that rocks fell because falling was an essential part of their nature. For Aristotle, seeking the ground was an intrinsic property of rocks. The same principle, he argued, also explained why things like acorns grew into oak trees. According to this explanation, every physical object in the Universe, from rocks to people, moved and changed because it had an internal purpose or goal.
Modern science has rejected this ‘teleological’ way of thinking. In the 17th and 18th centuries, scientists and philosophers began to chip away at Aristotle’s seemingly ‘spooky’ notion of intrinsic causes – spooky because they suggested that rocks and creatures were guided by something not entirely material. For those who rejected these Aristotelean explanations, such as Thomas Hobbes and René Descartes, organisms were simply complex machines animated by mechanisms. ‘Life is but a motion of limbs,’ wrote Hobbes in his Leviathan (1651). ‘For what is the heart, but a spring; and the nerves, but so many strings; and the joints, but so many wheels, giving motion to the whole body.’ The heart does not have the goal of circulating blood. It’s just a spring like any other. For many thinkers at the time, this view had real explanatory benefits because they knew something about how machines worked, including how to fix them. It was in this intellectual environment that Newton developed a powerful mechanical worldview, based on his discovery of gravitational fields. In a Newtonian universe, internal purpose doesn’t cause rocks to fall. They just fall, following a law of nature.
Mechanistic explanations, however, struggled to explain how life develops. How does a grass seed become a blade of grass, in the face of endless disturbances from its environment? Long after the mechanistic revolution, the philosopher Immanuel Kant confronted the stubborn problem of teleology and despaired. In 1790, he wrote in the Critique of Judgment that – as commonly paraphrased – ‘there will never be a Newton for a blade of grass.’ Less than a century later, with the publication of On the Origin of Species (1859), Charles Darwin seemed to crack the problem of biological teleology. Darwin’s ideas about natural selection appeared to explain how organisms, from grass seeds to bats, were able to pursue goals. The directing process was blind variation and the selective retention of favourable variants. Bats who sought moths and had an ever-improved capacity to track and catch them were favoured over those who were less goal directed and therefore had lesser capabilities. Though natural selection seemed to illuminate what Descartes, Hobbes and Kant could not, Darwin’s theory answered only half the problem of teleology. Selection explained where teleological systems like moth-seeking bats come from but didn’t answer how they find their goals.
So, how do goal-directed entities do it, moment by moment? How does an acorn seek its adult form? How does a homing torpedo find its target? Mechanistic thinking struggles to answer these questions. From a mechanical perspective, these systems look strangely future oriented. A sea turtle, hundreds of miles out to sea, can find the beach where it was born, a location that lies in its future. A developing embryo, without any thought of the future, constructs tissues and organs that it will not need until much later in life. And both do these things persistently: carried off course by a strong current, the sea turtle persistently finds a trajectory back toward its natal beach; despite errors in cell division and gene expression, an embryo is able to make corrections as it grows into its adult form. How is this possible?
Even though mechanistic thinking has failed to solve this teleological problem, it still dominates scientific thought. Today, we invoke mechanism to explain almost everything – including human goal-directed behaviour. To explain the growth of an acorn, we look to mechanisms in its genes. To explain the ocean voyages of a sea turtle, we look to mechanisms in its brain. And to explain our own thoughts and decisions, we focus on neural pathways and brain chemistry to explain decision-making. We explain behaviour in terms of evolutionary needs, such as survival or reproductive success. We may even think of our genes as ‘blueprints’. For some 20th-century thinkers, such as the US psychologist Burrhus Frederic Skinner, human brains are purely mechanistic. Skinner denied that people have goals at all. More recently, the primatologist Robert Sapolsky, based at Stanford University, and others have painted a mechanistic picture of us that denies we have free will.
We seem to have only two ways of explaining it: teleology or mechanism. Both are troublesome. Both are inadequate
And yet, despite centuries of rejection, teleology has not been banished. Most of us still have a deep intuition that there is more to our thinking and action than mere mechanisms. The feeling of being in love isn’t just the mechanical outcome of neurochemistry. We want to believe it is driven by our wants and intentions. Some of us, especially if moved by religious or spiritual impulses, might even see goals in the larger universe: ‘I am here for a purpose,’ you might think to yourself. For many, a world of pure mechanism seems insufficient. And beyond our intuitions about teleology, there are countless areas of science where teleological explanations are commonly deployed, even without any explicit recognition of them. Consider the debate over which parts of a genome are ‘functional’ (ie, they perform roles that are beneficial to an organism) and which are ‘non-functional’ (ie, useless remnants of evolution). The very idea that a gene can either be functional or non-functional implies that certain genes aim towards certain results, or have certain purposes for the organism, while others have no ends and are merely purposeless junk. So, even beyond our intuitions, teleology is so deeply entwined with science that there will be no getting rid of it anytime soon.
So, caught between modern science and our intuitions about teleology, we seem to have only two ways of explaining the apparent goal directedness in some systems: teleology or mechanism. Both are troublesome. Both are inadequate. In recognition of this problem, philosophers of biology and others have, in recent decades, been struggling to find an alternative. We believe we have found it: a third way that reconciles Aristotelian thinking about goal directedness with the mechanistic view of a Newtonian universe. This alternative explains the apparent seeking of all goal-directed entities, from developing acorns and migrating sea turtles to self-driving cars and human intentions. It proposes that a hidden architecture connects these entities. It even explains falling rocks.
We call it ‘field theory’.
The notion of ‘fields’ was originally developed by physicists such as Newton, Michael Faraday, Richard Feynman and others. In physics, the concept has been used to explain gravity, electromagnetism, and particle interactions in quantum theory. But fields have also been used in biology to explain the development of living things. In the mid-20th century, the Austrian biologist Paul Weiss proposed that, within an embryo, large ‘morphogenetic fields’ directed the behaviour of cells inside them. Together, these pioneers in physics and biology showed how objects in the Universe can be directed by often-invisible and large-scale external structures. Our version of field theory takes this as its starting point.
So what do fields do? How do they give us goal directedness? To answer this, we need to know something about what it means to seek a goal. Two mid-20th-century thinkers, the biologist Gerd Sommerhoff and the philosopher of science Ernest Nagel, made a simple observation about goal-directed objects: they all exhibit the same pattern of deviation and correction. When they inevitably deviate from the right trajectory – the right path toward a goal – these objects correct themselves, and direct themselves back toward their goal. A mouse embryo can be split in half at an early stage, and each half will regrow into a fully formed mouse. A person headed out to buy something can be diverted by another errand, but afterward redirect themselves toward the store. Sommerhoff and Nagel called this ability to recover from perturbations ‘persistence’.
The second signature behaviour of goal-directed entities is plasticity, the ability to find a trajectory toward a goal from a wide range of starting points. A sea turtle seeking the Florida beach where it was born can begin its journey from anywhere within a wide area, stretching hundreds of miles. A self-driving car can find its destination from almost anywhere. Persistence and plasticity are the common features that all goal-directed entities seem to share. And they point to the central problem of teleology: how do goal-directed entities persistently and plastically find their way toward a target that lies only in their future? How do they know which way to go? After all, the future cannot direct the past. What sort of strange causal chain is at work here?
These fields are not metaphorical. They are real and physical
The answer involves looking away from goal-directed entities, and instead considering what surrounds them. In our view, persistence and plasticity are possible because goal-directed entities – from turtles to self-driving cars – move and change within a larger field that envelops and directs them. Sea turtles, for example, are enveloped by Earth’s magnetic field and can use this field to find the beach where they were born. To make this journey, they rely on complex mechanisms in their brains, but also on a larger field that, from a turtle’s perspective, appears everywhere. If a current carries a turtle off course, the field is there to direct it back toward the right beach. Likewise for self-driving cars. Each car is immersed in a microwave field emanating from nearby cell-tower arrays and can use that field to locate its destination from anywhere within range of those towers. If forced to make a detour, the microwave field directs the car back toward its destination.
Our proposal is that fields direct the action of all goal-directed entities. In other words, goal directedness is the result of a particular architecture, a particular arrangement of large fields that contain and guide smaller entities. From this perspective, persistence and plasticity are possible only because a field is present wherever an entity wanders.
In field theory, fields are defined in terms of what the biologist Michael Levin calls ‘nonlocality’. They are structures whose influence extends over a broad area, not localised to any one point. Earth’s magnetic field is present not just locally, where the sea turtle happens to be at one moment, but wherever the turtle could accidentally wander. Our understanding of fields is even broader. It includes atmospheric fields that direct the formation of hurricanes, ecological fields that direct the migration of animal herds, and social fields that, to some extent, guide our wants and intentions. These fields are not metaphorical. They are real and physical. They can be detected, measured, and even manipulated.
Today, the standard scientific answer for how goal-directed entities work still involves pointing to internal mechanisms, following the tradition that can be traced back to Descartes, Hobbes and Newton. For example, how can we explain the way a homing torpedo, a classic mechanical goal-directed device, seeks its target? Most explanations would turn to internal feedback mechanisms inside the device. This is exactly what cyberneticists did in the mid-20th century, like the Mexican physician Arturo Rosenblueth. They argued that a homing torpedo uses feedback mechanisms to direct itself, detecting the sound of the target ship and responding when the sound fades by turning in the direction where it is louder. In a similar way, internal mechanisms are also used by contemporary biologists to explain the goal-directed behaviour of organisms.
Consider a dung beetle. When it enters a dung pile, a beetle will sculpt some of the dung into a ball. To escape rivals who might steal the ball, the beetle stands on top of it and rolls it away from the pile in a straight line. If it strays from a straight path, the beetle risks accidentally circling back to the pile, where it will encounter competition again. Anatomical studies have revealed that a complex mechanism in the beetle’s brain is involved in guiding its movements. From this perspective, the dung beetle’s goal-directed behaviour – moving in a straight line away from the pile – can be fully explained by some mechanism buried inside its brain. Such mechanistic approaches have dominated contemporary thinking on goal directedness.
The image of the Milky Way is a ‘light field’ that the beetle can use to orient its movements
The explanatory power of the mechanistic tradition is undeniable. But notice that these explanations of teleological phenomena are incomplete. The feedback mechanisms inside a homing torpedo have no information about the location of the target ship. That information is present only externally, in the ‘sound field’ generated by the target ship. And the mechanisms inside a beetle’s brain have by themselves no information about whether the beetle is moving in a straight line. Instead, beetles rolling their balls away from dung piles are guided by something that is not only external but light years away: the Milky Way galaxy. The image of the Milky Way is a ‘light field’, one that the beetle can use to orient its movements. The beetle’s brain mechanisms are critical parts of the causal chain, but they alone can’t tell a straight line from a very slightly curved one. When it comes to explaining ‘goals’, the mechanistic approach has a serious limitation.
Mechanisms are still important. They explain how goal-directed entities move and change, and how they execute decisions. But internal mechanisms viewed in isolation have no information about external goals. They can’t fully explain how an entity can persistently move toward its goal, even after it deviates. Mechanisms respond and execute; fields guide and direct.
So far, we have considered relatively simple examples. A more challenging case for field theory involves the development of embryos. To all appearances, embryos seek their adult form guided by internal genes, not an external field. Think of the fruit fly, Drosophila melanogaster, one of the most well-studied animals in scientific research. The mother fruit fly guides the earliest development of her growing embryos, but soon the process seems to proceed almost autonomously, as the embryo partitions itself into segments and then into body regions, with limbs, mouth, and other parts forming later. How does it do it? No information about the overall architecture of these body parts is present in the cells and tissues of the parts themselves, or in each organism’s genes. Once again, the answer requires looking outside.
Guidance is external, but not in the way you might think. It is not external to the entire embryo, but external to each body part. Guidance comes from ‘morphogenetic fields’ that are set up by the embryo itself. It is these fields that supply the cells contained within them with guidance about what to do: where to move, what to secrete, when to divide. These fields are composed of molecules, produced by genes deep inside an embryo’s cells, but the genes are not the source of guidance. They are just factories. And the molecules they manufacture combine to produce a chemical field around the growing body parts, directing their behaviour. This is where the notion of ‘internal’ and ‘external’ becomes trickier. This field is inside the embryo, of course, but is present over a broad area, outside the target cells and tissues, omnipresent and ready to correct them when they inevitably deviate.
Consider a question that still perplexes biologists. Why are your arms pretty much the same length? Genes inside the cells of a developing left arm have, by themselves, no information about the length of the developing right arm. This means that, unless tightly controlled, the cells in one arm might divide a bit faster than those in the other. This kind of variation occurs all the time in the development of organisms. If such variation is possible, then how do our arms grow to the same length? The answer is not yet known. One strong possibility is that some field exists – biochemical or even electrical – which is in touch with both arms, encompassing the cells in each. Such a field could persistently guide the growth process toward arms of the same length.
At each level, large fields direct the smaller entities contained within them
The simplified explanation above barely begins to account for the full complexity of fields in goal-directed systems. In embryos, there are multiple fields at the scale of the entire developing organism directing various tissue-level mechanisms inside. In turn, those tissues can also act as fields, directing the cells within them. And these cells in turn can also act as fields, directing various molecule-level mechanisms inside them, and so on. In the most complex systems, multiple levels of entities are nested within multiple fields. This telescoping of levels extends upward as well. Whole organisms are nested within local ecological fields, which in turn are nested within larger ecologies, and so on. What matters in these relationships – what makes goal directedness possible – are the spatial relationships among the nested entities. At each level, large fields direct the smaller entities contained within them.
By now, some might have noticed the teleological elephant in the room: our theory seems to suggest that Aristotle was right to think that falling rocks intend to fall – that they have a downward-seeking goal or purpose. After all, according to field theory, a falling rock is an entity persistently guided downward by an external (gravitational) field. And if teleology requires nothing more than a field directing a contained entity, then field theory would suggest that a falling rock really is teleological. To virtually all contemporary thinking on teleology, this is an outrageous conclusion.
We have two responses. First, not all instances of goal directedness are equal. A falling rock is among the simplest kind of teleological entity imaginable. It is minimally, negligibly, goal directed. Human intentions and purposes are among the most complex. According to field theory, historical and modern thinking on teleology has made an error. Much of this thinking assumes that teleology must be binary, that things are either goal directed or they’re not. We see teleology as something that comes in degrees. Second, allowing a falling rock to be somewhat teleological has the effect of drawing the life sciences and the physical sciences closer together, and we think that is a good thing. The very notion of a partition between them – with the life sciences allowing teleology while the physical sciences do not – would seem to imply there’s something about the life sciences that fails to be purely physical. We think that’s a mistake.
What makes field theory unique is that it is the only modern explanation of goal directedness that locates the source of goal directedness outside of the goal-directed entity. Most other modern theories are mechanistic, and even those that aren’t still point to internal processes or internal organisation, which we argue cannot have the information necessary to direct.
Though we know of no similar approaches to teleology, field theory did not arise in a vacuum. It has deep roots in the work of those studying the properties of nested, hierarchical systems. These studies stretch back almost a century and include research by social scientists (such as Herbert Simon), psychologists (Donald Campbell), biologists (Stanley Salthe) and philosophers (James Feibleman, Ernest Nagel and William Wimsatt). Although not all these thinkers are directly concerned with goal directedness, they explore the ways in which big things can affect little things nested within them, from societies affecting individuals to ecologies affecting species. This research has helped to explain the nature of hierarchical causation, how wholes affect their parts.
Finally, we turn to the most speculative application of field theory: human wants and intentions. If we’re right, then things like human culture and psychology – alongside all goal-directed phenomena – also involve direction by fields. That would mean there needs to be a hierarchical structure to human wanting. And this structure does seem to exist. Looking down, our cells and tissues have the same nested structure as other multicellular organisms. Looking up, we are individuals nested within and directed by small social ecologies (marriages, families, friend groups, etc), which in turn are nested within and directed by larger ones (economic, political and cultural entities), and so on. This is a greatly simplified explanation; even within organisms, the complex nesting of fields is never tidy.
Now consider the laws and legal systems that guide citizens into rough compliance. In this case, the ‘fields’ are the norms, expectations, forms of deterrence, and adjudication and enforcement systems that direct our wants and intentions, and therefore indirectly affect our thinking and actions. Just as Earth’s magnetic field acts on the turtle’s brain, telling it where to turn, the legal system acts on our wants and intentions from above. The same goes for the many economic fields in which we are immersed, guiding our preferences as workers and consumers. And the same also goes for the many social fields that contain us and guide us. These fields arise from partners, friends, families and the countless workplaces, neighbourhood groups, clubs and other social institutions in which we are immersed. The largest fields, like social and economic fields, are extraordinarily nonlocal, directing the wants and intentions of huge numbers of individuals over a large area. From this vantage point, human society emerges as a web of fields. People in a society, like cells in a developing organism, participate in multiple overlapping fields at the same time, which deliver different degrees of (sometimes conflicting) guidance.
But that is not the end of the story. It seems that some purposes or goals originate mostly in our heads. Here we speculate that wants and intentions direct purposeful thinking, speech and action, and must therefore be fields, too, providing both the motivational oomph that gets these processes moving and the directional focus that guides them. My desire for a cup of coffee moves me to think, say and do the things necessary to get one. By ‘wanting’ or ‘intending’ here we are referring to a large category of what might be called affective states, all closely related to emotion, including preferences, cares, feelings, motivations, and so on. This view of the mind, which dates back to the 18th-century philosopher David Hume, posits that our wants direct everything we deliberately think, say and do. Hume called our wants the ‘calm passions’ because, for him, thinking, speaking and acting are purely passive processes, having no goals of their own. We take a similar view: when we deliberately think about, say or do something, it is because some field, some want or intention, has motivated or directed us. Fields, and fields alone, motivate and direct.
Are we merely pawns pushed around by external fields, or are we free to make our own decisions?
To explain how this works, let’s consider a simpler animal. A brief downpour might nudge a squirrel toward wanting to seek shelter. But the desire to seek shelter is the direct cause of the animal’s thinking and motor movements as it heads toward shelter, not the rain – the rain just triggers the desire. Field theory predicts that when squirrel brains are better understood, we will discover that the thought and motor mechanisms involved in seeking shelter lie nested within some larger wanting field that directs them.
The squirrel case is interesting because, like us, squirrels initiate some actions almost entirely on their own, arising less from external triggers and more from internally generated wants and intentions. At any moment, a squirrel might choose to leap from branch to branch just for the exhilaration of near-flight. Field theory speculates that some large-scale pattern of neural activation, the desire for near-flight exhilaration, is a field that acts downwardly on the cognitive and motor centres enveloped by the field, causing the animal to plan, position itself, and leap.
We propose that this same architecture underlies human purposeful behaviour as well. Our deliberate decisions are driven by wants and intentions, which take the form of large fields in our brains that direct our cognitive, speech and motor centres. These fields might consist of large neural circuits. And the goal-directed mechanisms they guide – thinking, speaking and acting – might consist of smaller-scale circuits embedded within them. Like the eddies in a rushing river, the smaller circuits are embedded within the larger flow. Each eddy has its own dynamic, but an eddy’s overall movement is directed by the larger river that envelops it. Likewise, thinking, speaking and acting have their own dynamic, like the capacity of conscious thought to construct narratives, or the capacity of speech mechanisms to retrieve words and formulate sentences. However, their focus, their purposefulness, arises from the wanting or intending fields in which they are embedded. These fields are our motivations.
Our repertoire of wanting fields is enormous, far more diverse than the simple survival and reproductive drives envisioned in some simplistic biological models of intentionality. And they act across a wide range of time scales. An intention to throw a picnic directs a person to make a plan, invite others, collect supplies, travel to a park, and find a suitable spot. A desire for knowledge might direct a person to investigate, sign up for, and ultimately take an online course. A preference for a quieter life might direct someone to prepare for retirement over many years, so they can retire early. The picture is complicated further by the fact that wants are diverse, and sometimes conflicting, even on a single timescale. Owing to the complexity of human existence, we want many things at once. I both want that extra piece of cheesecake (because it’s tasty) and don’t want it (because I’ve eaten too much already) at the same time. I want to stay in school and see the world at the same time. The fields that direct us are interrelated, highly differentiated, and often in conflict.
This is where the question of free will begins to emerge: are we merely pawns pushed around by these external fields, or are we free to make our own decisions?
There is a very old line of thought, which has recently been reintroduced to the popular imagination by Sapolsky, that says we are not free. It says that all thought and action, indeed everything in the Universe, is fully determined by physical laws, and that this determinism is incompatible with free will. But this view, which sees determinism and free will as being at odds, is mistaken. According to a philosophical school called compatibilism, even if the world is perfectly deterministic, freedom is perfectly possible. Field theory is a kind of ‘compatibilist’ explanation of goal directedness.
According to our theory, freedom is direction by the fields within us. There is a temptation to regard direction imposed on us from anywhere as the opposite of freedom, but field theory reminds us that many imposed fields are our own wants and are, therefore, quite literally, parts of us. And when wants originate inside us, they are our wants, and the decisions they motivate are our decisions, regardless of whether they are determined by the external world and the fields that make it up. In this view, freedom is not the total absence of deterministic causation – it would make no sense to be free of your own wants and intentions. In a very real way, your wants and intentions are you, and no one wants to be free of themselves. The freedom we all seek is the freedom to think, say and do what we ourselves deeply want. It is not to be undetermined or free of causes.
What evidence exists for our theory of ‘wanting’ fields? The truth is that we are out on a limb, one that is both weak and strong. It is weak because there seems to be little positive evidentiary support, neurologically at least, for the notion that our wants manifest as large fields containing thought and action mechanisms. But the theory is also strong because it is not contradicted by existing research. Much is known in neuroanatomy and neuropsychology about the neural correlates of emotion. Less is known about calmer affective states such as wanting and intending. When it comes to motivations at a molecular level, large-scale neurotransmitter fields involving serotonin or dopamine could be the mediators of our wants and intentions. However, there are other candidates as well, from electromagnetic fields acting over large areas within the brain to neural circuits involving clusters of neurons that are not specific to any one neurotransmitter. Enough mystery remains to support a range of possibilities about how these fields might work.
One of the most valuable aspects of our theory is that it offers empirical guidance. It suggests that researchers hoping to understand human wanting should look for large-scale structures – larger than the thought and action systems they guide. Experiments should seek structures with these systems embedded within them. Of course, field theory, like any theory about the physical world, could turn out to be wrong about how human wanting works. And that, too, is a virtue of the theory. In good scientific fashion, it sets itself up for possible falsification.
It’s possible that our purposes have something deep in common with acorns and dung beetles
Fields are an old idea but, to a world steeped in mechanistic thinking, they offer something new. They expand our explanatory arsenal, supplementing pure mechanism in a way that explains the otherwise unexplained. They help to answer one of the oldest problems in philosophy and science: why do things in the Universe appear to have goals or purposes?
Field theory carries with it a message of unity, bringing together all teleological systems under a shared architecture, revealing a continuity in nature that has long been suspected, at least since Aristotle. Disparate phenomena, from physics to psychology, are unified under a single explanatory framework. The theory raises the possibility that our purposes have something deep in common with other goal-directed systems like acorns and dung beetles, as well as with even simpler ones, like self-driving cars and, yes, even falling rocks.
We acknowledge there are problems to resolve. Fields are often elusive, invisible and intangible. In particular, the fields that guide us as people, the wants our consciousness is bathed in, are poorly understood. We see them only vaguely, from inside. Like gravitational fields, they seem to be everywhere and nowhere in particular. And like gravitational fields, they wield a mysterious power we have yet to fully understand.
