Botanical Philosophy

Botanical Philosophy

Botany is more philosophically interesting than we like to think. Gradually, animals have found their way onto the philosophical curriculum; now it is time for plants to take their rightful place. Plants are puzzling; they pose hard problems. There are botanical mysteries. Plants compose about 98% of the earth’s biomass; animals the remaining 2%. They have been around since the beginning. They exhibit enormous variety. They are everywhere. They are the primary source of biological energy. Without them we are all dead. They sexually reproduce and have myriad genes. They evolve by mutation and natural selection. They are living beings, organisms, not mere lumps of matter. They are subject to the law of the survival of the fittest. One might wonder how exactly they differ from animals—aren’t they a type of animal? That possibility is reinforced by other characteristics possessed by plants that tend not to be noticed or are underplayed. Plants move, compete, parasitize, predate, attract, poison, consume flesh, stab, and grip. Their movement is inconspicuous but real: flowers open and close, seek the light, transform, grow, wilt and die. The Venus fly-trap snaps shut. Vines probe and strangle. Pollen is discharged into the air. It’s a dynamic botanical world. Why the sharp division between animals and plants? Aren’t trees the botanical analogue of elephants and giraffes? Isn’t the drama of the selfish genes much the same in both cases? We already classify flora and fauna together under the title “organism”, so why not drop the insistence on a major biological division? Animals are closer to humans than we have historically recognized, so why not acknowledge that plants are closer to animals than we have historically recognized? The traditional divisions are too stark and anthropocentric.[1]

But I am concerned with philosophical questions not taxonomic ones. I want to know about plant minds. Don’t worry, I’m not about to suggest that plants are conscious beings; I want to say that plants have features close to mental features, but they systematically lack consciousness. The features are beliefs and desires: plants have goals (desires) and means of achieving them (instrumental beliefs). They need the sun and orient themselves appropriately: they “desire” sunlight and “believe” this action is the best way to get it. We need not take this too literally; after all, most animal goal-directed behavior is not literally the result of beliefs and desires—neither is much human behavior come to that. We don’t have terms for the traits in question, so we fall back on “desire” and “belief”; the important point is that there is a natural biological kind here. Human action is just a special case of this more general organic configuration, and probably evolved from it. We really need some neologisms so that we can codify the facts better. We might try “cognize” for the belief part and “conate” for the desire part: the plant conates (needs, craves) the sun and cognizes (knows, perceives) that such and such an orientation is the best way to get it. We thus get “cognizance-conation psychology”. The philosophy of action will take in this broader category. We could call it “bio-psychology”, stripping the word “psychology” of its specifically human interpretation.[2] It is a kind of unconscious or proto-conscious psychology. Plants have an embryonic psychology, a psychology-in-the-making. They act under the influence of a conative and cognitive pair—needs and means to satisfying needs. The need can’t act on its own without some means of achieving satisfaction, and the cognizance of a means is pointless without a need to satisfy. The basic structure of folk psychology thus applies in the case of plants (and also simple animals). So far, then, we have brought plants into the ontological realm of animals (including humans); we have drawn a continuous line. We have made the psychology of plants line up with their biology vis-à-vis animals.

I have said nothing about consciousness—sentience, sensation. My question is this: why aren’t plants conscious? Or better: why haven’t plants evolved consciousness? Why haven’t they evolved an organ functionally like the brain?  Why no sentience organ? Animals have done it often and there is good reason for that, but plants have never done it—despite their variety, extensiveness, and complexity. You would think that a mutation that favors consciousness might have occurred and been selected for, but nothing like that has happened. Our puzzle, then, is this: why are plants not conscious, ever? Don’t say it’s because they never evolved a central nervous system—that just begs the question. The question is why they didn’t evolve such a nervous system. What prevents plants from becoming conscious? Here we might recall the old science fiction thriller The Day of the Triffids, about a species of plant that arises on planet Earth: they terrorize the human population as they amble about showing every sign of intelligence, wielding their lethal stinger. We might also imagine flower dinosaurs stalking (literally) the planet and wreaking havoc. And surely there is a planet somewhere in the universe on which sentient trees sway and trample. Yet on Earth we have no such specimens to wonder at and collect (and slaughter)—why? What if the reverse were the case, with all the consciousness concentrated in the plants and none in the animals? Wouldn’t that seem contrary to nature, bizarrely puzzling? Brainy conscious plants but brainless robotic animals! What we would expect is that consciousness evolved in plants, as it did in animals, with some plants having more of it than others, and some with none. Wouldn’t a brainy plant do well in the struggle for survival? If consciousness evolved in animals as a means of evading predators, why didn’t the same thing happen in plants? It’s a mystery, is it not? Why are plants so bloody primitive?

A certain response to this mystery is likely to spring to mind—namely, that plants are conscious. Consciousness has evolved in them. It is all around us in our gardens and fields. We are just too prejudiced to admit it. One has to concede the theoretical motivation for such a view, but surely it is too extreme, for obvious reasons. We just have no empirical grounds for ascribing sentience to plants (even majestic trees). They simply don’t have what it takes. The puzzle remains. And it is compounded by the point I made earlier: plants have a kind of primitive embryonic psychology. If they evolved a psychology, why didn’t they evolve a conscious mind to go with it? Why an unconscious psychology? Desire and belief go hand in hand with consciousness in animals and yet the tie is severed in the case of plants. Plants are conceptually puzzling in this respect. They seem to violate laws of nature—in this case the law that psychology and consciousness belong together. There is a semblance of mind, hinting at consciousness, but there is no real consciousness in there. The hint is misleading. It is certainly tempting to attribute consciousness to plants, but in sober scientific truth there is no consciousness lurking within. Why is nature behaving so weirdly? Why didn’t it just go ahead and produce plant consciousness as it produced animal consciousness? Why is there nothing it’s like to be a plant, any plant? There is something it’s like to be a triffid (though we have no idea what it is), but there are no triffids on planet Earth. A pet triffid would be nice; you could keep sentient triffids in your garden and pet them. Your flowers might grow to love you and you them. But we have been deprived of this pleasure for mysterious reasons. That is fortunate for moral vegetarians, but wouldn’t it be nice if at least some plants had minds? As it is, we have no idea why plants never developed (sophisticated) minds. They started on the yellow-brick road to consciousness (that glittering emerald city), but never got very far for reasons that remain unclear.[3]

[1] Dr. Dolittle had talking animals, but what about talking plants? Plants are said to communicate chemically.

[2] Not that this an easy thing to do and there is really no term that captures what we want. The plant’s behavior is mind-like but not strictly mental. So, what term covers both? We might have to invent a completely new term, say “zeugology”. I will keep using the term “psychology” for convenience in what follows with the caveat noted.

[3] How contingent is this–in how many possible worlds are plants conscious? My intuition is that they are conscious in many worlds; not much needs to be added to actual plants to raise them to the level of consciousness. My feeling is that they got pretty close, but never made the grade. A small genetic modification could have brought them there. Not that we have any idea what makes an organism conscious, so we are intuiting in a vacuum; but it is hard to find a principled reason why they are not conscious, so it is natural to suppose them not so far off. If I came across a flower that had a bunch of neurons nestled in its petals, I would plump for consciousness; I wouldn’t need much persuading. But then I am a plant (and animal) lover. How could flowers be so beautiful and yet lack awareness of their own beauty? (You might want to listen to the song “Red Daisy” by Billy Strings to get a sense of this: “Daisy, red daisy, growin’ on a hill, sunshine fallin’ on your petals so fine”.)