Thinking Like a Plant

A little while ago no one would admit that animals had intelligence. This is now conceded. At any rate, then, vegetables had no intelligence. This is being fast disputed.

—Samuel Butler^[1]

A Philosophy of Vegetables?
The history of philosophy can be read as a series of meditations on the relationship between humans and animals. Ever since Aristotle defined human beings as “rational animals,” philosophers have busied themselves with discovering and demarcating that element of “rationality” or “intelligence” that distinguishes human beings from their animal kin. Nearly every burning issue in philosophy—from the nature of knowledge and mind to the prescriptions of ethics and politics—has been animated by a reflection on the space between the “rational” and the “animal” in Aristotle’s generative definition. All of modern ethics, for example—from David Hume and Immanuel Kant through Peter Singer and Alain Badiou—has concerned itself with the question of moral boundaries and, hence, with the question: “Do animals (the human animal included) qualify for ethical consideration?”


But what have philosophers had to say about “vegetables,” those other living inhabitants of the natural world to whom humans and animals literally (and perhaps figuratively) owe their sustenance? After all, in the Judeo-Christian tradition from which philosophy undeniably grows, it is to a plant and its fruit that human beings owe their “knowledge of good and evil” and therefore their humanity. From the ontological “tree of Porphyry” and d’Alembert and Diderot’s “tree of knowledge” to Hegel’s oak tree, Derrida’s “graft,” and Deleuze and Guattari’s “rhizome,” philosophy has lived on vegetative metaphors.^[2] But what of the vegetative stuff itself? Has there ever been a “philosophy of vegetables,” a philosophy of nature that considers plants intrinsically interesting and not merely low-grade stepping stones on the climb toward human beings?


The Great Divide In truth, philosophers have not been silent about vegetables; but nor have they been either prolix or kind. When it comes to plants, philosophers tend to fall into one of two camps which, despite apparent differences, generally share the same low estimation of the vegetable. For one tradition, which we might call super-naturalist, a deep chasm separates the properly human from the natural, which comprises animals, vegetables, and minerals. Human beings, according to this view, are composite creatures, half God, half animal, the respective parts of which belong to entirely different worlds. In Timaeus, Plato presents this view nicely via the metaphysical inversion of a botanical metaphor:


We ought to think of the most sovereign part of our soul as god’s gift to us, given to be our guiding spirit. This, of course, is the type of soul that, as we maintain, resides in the top part of our bodies. It raises us up from the earth and toward what is akin to us in heaven, as though we were plants grown not from earth but from heaven. ... For it is from heaven, the place which our souls were originally born, that the divine part suspends our head, i.e., our root, and so keeps our whole body erect.^[3]

If reason (logistikon), the highest part of the soul, is a plant, it is one of extraterrestrial origin. It grows not up from the earth, but down from heaven. And both its soil and its substance are immaterial and incorporeal—in a word, super-natural.


Extending this line of thought, Descartes maintains that the human is the rational, and that non-human animals are to be considered mere machines without souls or thoughts—like plants, subject simply to natural laws. Radicalizing Plato’s dualism, Kant argues that human beings belong simultaneously to two worlds—the natural and the rational, the phenomenal and the noumenal—and that our humanity is evidenced by our capacity to suspend our commitments to the natural world in order to live in the metaphysical, super-natural world of freedom and reason.


If all of this sounds peculiarly old-fashioned, it is worth noting that both Slavoj Žižek and Alain Badiou have recently asserted powerful versions of this view. Žižek, for example, believes that human beings are defined by their capacity to extend themselves “beyond the pleasure principle,” beyond the animal world of ordinary physical needs and satisfactions. According to Žižek, the properly human is that which strives “toward the unattainable absolute object which, on account of its very inaccessibility, forever captivates our desire.”^[4]

What does all this have to do with vegetables? Nothing at all, and that is precisely the point. For, according to this view, the properly human world is fundamentally alien to the natural world. And if animals fall on one side of this divide, all the more so do vegetables. We will not find a philosophy of vegetables here.


The Scala Naturae
The other tradition is more promising. Explicitly naturalist, it can be traced back to Aristotle, that supreme biologist among philosophers. For Aristotle, the “soul” (psyche) is simply the principle of life, “the cause and first principle of the living body.”^[5] Hence, every living thing has a soul. Indeed, for Aristotle, there are three types of soul, corresponding to the three broad classes of living things: vegetables, animals, and humans. The most basic of all is the “vegetative” soul. Its functions are nutrition, growth, and reproduction, operations without which no entity could be called “alive.” Unlike the plant, which is tied to the earth and more or less immobile, the animal moves all over the place, driven by those faculties that define the animal soul: “perception” and “appetite.” Though mobile, animals, like plants, are passive: as plants follow the sun, animals follow their appetites. Only human beings, the souls of which are defined by “reason,” “intellect,” and “contemplation,” are truly active, capable of making genuine choices and actively engaging in theoretical pursuits.

Though exemplified by different natural kinds, these three forms of soul represent different principles that, like Russian nesting dolls, can coexist together in one body. The soul of plants is exclusively vegetative. But animals contain both animal and vegetative souls, and human beings contain all three. At bottom, then, human beings and animals are vegetative, a trait that manifests itself in sleep and in the involuntary and unconscious operations of the body. Hence, the comatose human being, deprived of everything but the most rudimentary life, is deemed “a vegetable.”


Aristotle’s conception of the soul and of nature profoundly affected the history of philosophy. Versions of it can be found in Aquinas, Leibniz, Herder, Hegel, Schelling, Schopenhauer, and in most pre-Darwinian evolutionary thinkers. Its basic idea is that of the scala naturae, a view of nature as consisting of various levels increasing in perfection.^[6] In contrast with the super-naturalists, Aristotle takes nature to be continuous and, therefore, considers vegetables worthy of philosophical consideration. Yet his view is not fully naturalist. Explicitly hierarchical and progressive, it takes human beings to be the aim and goal of the natural world and, in rare moments, even suggests that the excellence of human being (theoria: contemplation) consists in its capacity to transcend nature.^[7] His biology is also typological and essentialist. Vegetables, animals, and human beings are distinct natural kinds, separated from one another by an unbridgeable gap. While the three types of soul may nest within one another, there is no question of any real continuity.

Vegetative Thought With Darwin, we finally begin to glimpse the possibility of a genuine philosophy of vegetables. For his theory directly challenges typological, essentialist, and hierarchical conceptions of nature. According to Darwin, the organic world is a vast temporal and spatial continuum; and the concept of “species” does not name a fixed essence but simply a conceptual and statistical abstraction that allows us pragmatically to sort what is really a fluid distribution of individuals, differences, and variations. Moreover, despite the misreadings of Herbert Spencer and Social Darwinists ever since, Darwin’s view is explicitly non-hierarchical and non-progressive. “Never use the words higher or lower,” he wrote in the margins of a progressivist text.^[8]

Radical naturalists such as Friedrich Nietzsche took Darwin’s words to heart and spun them in a philosophical direction.^[9] Yet it was left to Nietzsche’s contemporary, the empiricist philosopher, evolutionary theorist, and novelist Samuel Butler, to push naturalism to its limits and to inaugurate a bona fide philosophy of vegetables. The most thoroughgoing of naturalists, Butler insists that nature—from rocks and plants, through animals and humans, to the “inorganic life” of machines—is one, and operates according to a basic set of evolutionary principles. Hence, Butler cannot tolerate the idea that “consciousness” or “intelligence” somehow sets human beings apart from and above the rest of nature. On the contrary, he insists that “consciousness” is secondary to “habit,” the basic process of life. Indeed, for Butler, one is “conscious” only of what one has not yet mastered, what has not yet become unconscious memory and habit. To say of animals and plants that their activity is not conscious is to say that they perform such activities with perfect mastery. Far from elevating human beings, then, consciousness is a sign of human inexperience and frailty.^[10]

For Butler, “habit” is the achievement not of the individual but of the evolutionary history of which it is the terminus. That is, each individual inherits (as a kind of unconscious “memory”) all the habits of its ancestors. And it is this habitual activity, argues Butler, that constitutes genuine “knowledge” and “intelligence.” One will not understand these by studying the feeble deliberations of human beings and conscious thought. Rather, one must look to the most unconscious of living things: plants.


Butler’s fascination with plants is evident throughout his philosophical and evolutionary writings. Yet it is nowhere more richly developed than in a series of chapters in his extraordinary novel, Erewhon.^[11] “Shall we say that the plant does not know what it is doing merely because it has no eyes, or ears, or brains?” Butler continues:


Even a potato in a dark cellar has a certain low cunning about him which serves him in excellent stead. He knows perfectly well what he wants and how to get it. He sees the light coming from the cellar window and sends his shoots crawling straight thereto: they will crawl along the floor and up the wall and out the cellar window; if there be a little earth anywhere on the journey he will find it and use it for his own ends. What deliberation he may exercise in the manner of his roots when he is planted in the earth is a thing unknown to us, but we can imagine him saying, ‘I will have a tuber here and a tuber there, and I will suck whatsoever advantage I can from all my surroundings. This neighbor I will overshadow, and that I will undermine; and what I can do shall be the limit of what I will do. He that is stronger and better placed than I shall overcome me, and him that is weaker I will overcome.’ The potato says these things by doing them, which is the best of languages. What is consciousness if this is not consciousness? We find it difficult to sympathize with the emotions of a potato: so do we with those of an oyster. Neither of these things makes a noise on being boiled or opened, and noise appeals to us more strongly than anything else, because we make so much about our own sufferings. Since, then, they do not annoy us by any expression of pain we call them emotionless; and so qua mankind they are; but mankind is not everybody.^[12]

Several chapters later, this view is taken up again through the mouth of a philosopher who happens also to be a Professor of Botany. This philosopher, the narrator tells us,


connected all, both animal and vegetable development, with intelligence, either spent and now unconscious, or still unspent and conscious. ... Granting that vegetable intelligence at first sight appears to differ materially from animal, yet, he urged, it is like it in the one essential fact that though it has evidently busied itself about matters vital to the well-being of the organism that possesses it, it has never shown the slightest tendency to occupy itself with anything else. This, he insisted, is as great a proof of intelligence as any living being can give. ‘Plants,’ said he, ‘show no sign of interesting themselves in human affairs. We shall never get a rose to understand that five times seven are thirty-five, and there is no use in talking to an oak about fluctuations in the price of stocks. Hence we say that the oak and the rose are unintelligent, and on finding that they do not understand our business conclude that they do not understand their own. But what can a creature who talks in this way know about intelligence? Which shows greater signs of intelligence? He, or the rose and oak? And when we call plants stupid for not understanding our business, how capable do we show ourselves of understanding theirs? Can we form even the faintest conception of the way in which a seed from a rose-tree turns earth, air, warmth and water into a rose full-blown? Where does it get its colour from? From the earth, air, &c.? Yes—but how? Those petals of such ineffable texture—that hue that outvies the cheek of a child—that scent again? Look at earth, air, and water—these are all the raw material that the rose has got to work with; does it show any sign of want of intelligence in the alchemy with which it turns mud into rose-leaves? What chemist can do anything comparable? Why does no one try? Simply because every one knows that no human intelligence is equal to the task. We give it up. It is the rose’s department; let the rose attend to it—and be dubbed unintelligent because it baffles us by the miracles it works, and the unconcerned businesslike way in which it works them. ... What is to be intelligent if to know how to do what one wants to do, and to do it repeatedly, is not to be intelligent?^[13]

Here and elsewhere, Butler aims to think naturalism through to its conclusions. He rejects the metaphysical, super-natural view that allegedly “human” endowments such as reason, language, consciousness, and intelligence are signs of our extra-natural origin or essence. He equally rejects the pseudo-naturalist view that, even if human beings are embedded within nature, they constitute the highest rung on the scala naturae. Rather, Butler places reason and consciousness firmly within the natural world and shows that they are but forms of instinct and habit, though weak ones at that. He goes even further. Strategically inverting Aristotle’s hierarchy, Butler suggests that one can learn more about knowledge and intelligence by focusing on the vegetable kingdom, and that human beings and animals are, at best, kinds of vegetable.


God or Vegetables It should be noted that the philosopher-botanist Butler presents in Erewhon offers his propositions with the aim of advocating protection of “the rights of vegetables” and a diet consisting only in plants that have “died a natural death, such as fruit that was lying on the ground and about to rot, or cabbage-leaves that had turned yellow in late autumn. These and other like garbage he declared to be the only food that might be eaten with a clear conscience.”^[14]

With this, Butler and his philosopher-botanist invite the wrath of philosophical ethicist Peter Singer and his civilian wing, PETA (People for the Ethical Treatment of Animals). Keen on dissolving the boundaries between human beings and animals, hence deeming animals worthy of ethical treatment and protection from harm, Singer recoils at the idea of extending this principle to vegetables. Neither Singer nor PETA are willing to take seriously any advocacy of “the rights of vegetables,” treating such claims as merely botched attempts at offering a reductio ad absurdum of animal rights and vegetarianism.^[15]

In truth, Butler’s narrator suspects the philosopher-botanist of having just such wan aim in mind. “Being in secret a great meat-eater,” the narrator suggests, he “had no other end in view than reducing the prohibition against eating animal food to an absurdity” by showing the Erewhonians “that they must either sin to a certain extent, or die.”^[16] Indeed, the result of his arguments is that “the acts forbidding the use of meat were repealed by a considerable majority.”^[17]

Yet, the absurd conclusion notwithstanding, the arguments of Butler and his philosopher-botanist draw powerful ontological and ethical conclusions from a naturalism that, in the wake of Darwin, cannot but be compelling. There are no essential divisions in nature, and the slippery slope down the natural continuum can only arbitrarily be said to hit a wall at the border between animal and plant life. In practice, of course, we draw boundaries where we like. But such boundaries can only ever be pragmatic choices, never ontological givens.


Singer and PETA suggest that ethical behavior is a matter of decreasing pain and suffering, and that, unlike human beings and animals, plants do not suffer. Yet Butler’s rigorous naturalism comes to question this as well. “It is generally held that animals feel,” he writes,


it will soon be generally held that plants feel; after that it will be held that stones also can feel. For, as no matter is so organic that there is not some of the inorganic in it, so, also, no matter is so inorganic that there is not some of the organic in it. We know that we have nerves and that we feel, it does not follow that other things do not feel because they have no nerves—it only follows that they do not feel as we do.^[18]

Here Butler joins company with plant physiologist Jagadis Chandra Bose, who demonstrated that plants indeed have a kind of nervous system and respond to stimuli much in the way that an animal does, though, of course, without making a noise.^[19] Indeed, though Butler makes no claim to scientific value or accuracy,^[20] botanical research has, in the century since his death, lent credence to his philosophical speculations concerning vegetable intelligence and the natural continuum. Along Butlerian lines, David Attenborough has recently argued that, in a very real sense, plants can see, communicate with one another, estimate time, and count, though of course they do so by very different means and in very different ways than do animals and human beings and, above all, on a very different time-scale.^[21] Even more recently, science writers Evan Eisenberg and Michael Pollan have argued that, in their own unconscious ways, plants conspire with human beings to conquer space and to perpetuate themselves.^[22]

Scientific claims aside, Butler reminds us that philosophers have neglected vegetables, and have done so at their peril. Initiating another Copernican Revolution in philosophy, Butler shows us that a rigorous naturalist must be a philosopher of vegetables and that the alternative is an illegitimate anthropocentrism, which is to say a theology (since anthropocentrism has always thrived on the idea that human beings owe their humanity to something other than, higher than, nature: something divine). To paraphrase Nietzsche, we might say: God vs. vegetables: That is the complete, the genuine antagonism–there, the ‘beyond’; here, the golden nature.