Thursday, January 27, 2022

What Is It Like to Be a Plant?

guest post by Amy Kind

Is there something that it’s like to be plant? I suspect that most people hearing this question would unhesitatingly answer in the negative. In this respect, plants seem quite different from animals. In fact, it’s this difference that undoubtedly helps to explain why so many people who feel squeamish about eating animal products don’t feel at all squeamish about eating fruits, vegetables, and other plant products.

Philosophical assessment of the consciousness of plants and animals is generally in line with this common-sense judgment. Though there’s disagreement about how far consciousness extends throughout the animal kingdom (Are ants conscious? What about garden snails?), and though there’s disagreement about whether and to what extent we can understand the nature of non-human consciousness (can we know, for example, what it’s like to be a bat?), there is general philosophical agreement that at least some non-human animals are conscious. In contrast, very few (if any) philosophers have defended the claim that plants are conscious. Even philosophers such as Chauncy Maher who have recently argued that plants have minds tend not to commit to the claim that there’s something that it’s like to be a plant.

In refraining from this commitment, Maher suggests that the predicate “consciousness” is not determinate when it comes to plants, i.e., there is (currently) no fact of the matter about whether plants are or are not conscious. Maybe they are; maybe they’re not. But given our present understanding of the nature of consciousness, Maher claims that “our standards don’t yet settle whether plants belong in the extension of the term.” When it comes to plants, we simply don’t yet have an adequate understanding of what it would be for them to be conscious.

On this score, however, a recent science fiction duology by Sue Burke helps provide some important insight. Semiosis, the first book in the duology, takes place in the 2060s. Fleeing the wars and environment crises that have engulfed earth, a group of humans united by pacifist ideals travel to a distant planet they name Pax. In their efforts to build a settlement, they eventually come across signs of another sentient animal species on the planet, the Glassmakers. But the Glassmakers are not their only encounter with sentience. As they soon discover, the bamboo-like plant (“rainbow bamboo”) that grows rampant in the area they are settling is also sentient. This plant, whom they name Stevland, initiates communication with the humans and eventually becomes integrated into their society as a full and valuable member – even taking on a leadership role.

We are told even more about Stevland in Interference, the second book in the duology, which takes place about a hundred years after the events of Semiosis when a team of earth scientists travel to Pax to find out what had happened to the original expedition (with whom they had long lost contact). With the more sophisticated equipment these scientists bring, it’s discovered that the rainbow bamboo on Pax has nerve tissue, and that Stevland has a collection of neurons that deserved to be called a brain.

Rainbow bamboo, and Stevland in particular, is clearly very different from bamboo plants on earth. For one thing, earth plants do not adopt names and pronouns for themselves. More to the point for our discussion here, earth bamboo plants lack neurons. Earth bamboo plants also lack the kind of linguistic and emotional capacities that Stevland has, nor can they develop and execute complex and temporally extended plans. But when we set aside these capacities that Stevland has in virtue of his sentience, he nonetheless exhibits a lot of the properties that seem essential or constitutive of plants in general. He relies on sunlight and water, and he is in competition with other nearby plants for these resources. He does not need to sleep. He has a long life span. He is situated in one place with no capacity to move himself to an entirely different place. But he is distributed over a large area, and he can extend his presence to connected terrain. He can survive significant damage to various of his parts and can even survive their destruction. Moreover, such parts can be regrown.

All of these features of plants seem relevant to how they would experience the world. What would give a plant joy? What would make it angry? Given that a plant lacks visual and auditory sense capacities, how would it gain an understanding of its environment? How would it initiate communication? How would it form relationships – whether friendly or unfriendly – with others? Given that a plant lacks mobility, how would it execute plans? How would it strike at its enemies? (Interestingly, and non-coincidentally, Burke herself started thinking seriously about the nature of plant and plant behavior after she witnessed one of her house plants “attacking” another.) Thus, even though Stevland’s neuronal system makes him different from earth plants – so different that, as plant biologist Laci Gerhart has complained, a “scientific reader will struggle with … the seemingly preposterous abilities of Pax’s plant life compared to their terran equivalents.” – the important similarities that he shares with earth plants means that Burke’s exploration of his sentience can help us understand more generally what plant sentience might be like. Unsurprisingly, this was something I thought a lot about as I read the books.

So how does Stevland do the kinds of things just mentioned? Much of his behavior proceeds via his root system. He learns about his environment by ways of his roots. He can extend his roots in new directions, and he does so for many purposes, whether exploring new terrain or connecting and communicating with other plants. He makes additional communicative efforts by generating smells, specific leaf patterns, or distributing chemicals through the production of fruit. His relationships with other plants are driven largely by need. And he has a great deal of patience.

When we think about the features of plants delineated above, this all makes a lot of sense. For example, the relatively long life span of plant species like bamboo – and the fact that they are situated in a single place – suggests that their temporal experience, and correspondingly their patience, would likely be different from that of humans. Moreover, because their situatedness means their only options for relationships are those nearby, we could reasonably expect that plant relationships would be different from human relationships. Here I’ll note that a related point is made by Brandon Sanderson in Cytonic, the third novel in his Skyward series. As a sentient alien from a (non-animal) crystalline species tells the human protagonist: “my species evolved as motionless individuals who would spend decades next to one another. It’s not in our nature to argue. Unlike motile species, we cannot simply walk away if we make one another angry.”

So, is there something it is like to be a plant? Maybe there is, maybe there’s not. Burke’s duology doesn’t really address this question. But in helping us understand something about what it might be like to be a plant if there were something it were like to be a plant, the books pave the way towards a better understanding of the standards we should use in attributing consciousness to other non-human entities. Thus, even if Maher is right that it’s currently indeterminate about whether the predicate “consciousness” should apply to plants, reflections on Burke’s extended thought experiment helps us to make progress in resolving the indeterminacy.

[image source]

14 comments:

SelfAwarePatterns said...

It seems like the question of whether there is something it is like to be a plant is too vague. We need to agree on what we mean by the phrase "something it is like". One possible answer to that might be to have a model of self. Asking if there is a model of self present seems like a more concrete and easier to address question.

Stevland has a nervous system, and so presumably a place for that model to exist. And its behavior and capabilities seem to require it, or something functionally equivalent. If we're were going to say Earth plants have a model of self, then we have to identify where it could reside, and what its role might be in observed plant behavior.

Of course, if someone rejects my answer to what is meant by "something it is like", they can supply their own, and the question can be examined using that version. But without some variation of that clarification, it seems like we're stuck.

Arnold said...

Some thought is for duty and being...

Can we learn to separate the fiction from the non fiction in ourselves...
...That fiction is more attractive, still today, than non fiction...

And to balance these forces within ourselves...
...May be, more consciousness...

chinaphil said...

The BBC has a David Attenborough nature documentary running right now called the Green Planet, in which time-lapse photography reveals plants displaying behaviour that looks very purposeful. They just do it a lot more slowly than animals. It makes for some interesting reflections on what kinds of lives these entities have.
I still think that the question of consciousness can't be far removed from the question of representation. If your question is "Is there something that it's like to be a plant?" then that seems to be asking whether there is some way in which the plant can reflect on itself; which would require that the plant have a representation of itself. I don't think that having the capacity to create internal representations is sufficient for consciousness, but I do think that it must be a necessary condition.

Anonymous said...

As I read this, I couldn't help but think of this piece I read a few weeks ago: https://psyche.co/ideas/the-fungal-mind-on-the-evidence-for-mushroom-intelligence

I know fungus and plants are different, but they have similarities.

I also think that, in some sense, since plants react to stimuli and communicate, there has to be something that it is like to be a plant.

Luke Roelofs said...

Hedda Hassel Mørch observes that “In terms of consciousness… a plant would be a society, not an individual” - she derives that specifically from IIT, but I think it probably applies on other theories too.

In particular, it looks to me like the decentralised nature of a plant body removes much of what Wayne Wu calls the ‘many-many’ problem, of integrating many sensory inputs to guide a single choice among many possible actions that the organism as a whole can take. Since plants don’t move as a whole unit, they can let a lot of their responses be local, or make various responses at various times without worrying that they’ll cancel out or interfere with each other.

I think there’s some plausibility to the thought that the many-many problem, or some similar problem of integration and prioritisation, is why we have attentional structure in our minds. If plants (or fungi, as Unknown notes) are decentralised in a way that removes that problem, they likely don’t have attention - if they’re conscious, many things might enter their consciousness without any focusing or centring on particular elements. If it’s a society, it’s not one with a leadership or general meetings; it’s one with lots of small groups who will transmit information to other small groups, who may do something about it, eventually, but without anything that would even yield the illusion of a ‘Cartesian theater’.

(And given the wood-wide-web, that society might extend fairly continuously into other adjacent plants…)

I’m not sure whether Stevland and others should be read as retaining that characteristic decentralisation - I guess I should read the book!

Gene Anderson said...

Plants detect predators, especially insects nibbling on them, and respond with significant chemical changes that resist the bugs. Moreover, if they have mycelia, they communicate via the mycelia with other plants and warn them. Or they can just release chemicals into the air that trigger resistant behavior by other plants, but that seems mindless, not real communication like the mycelia thing--apparently the plants have to "decide" in some sense to do that. It seems to me about the level of sentience of a sponge or hydra. Better than nothing, but not notably conscious.

Arnold said...

some of us are to old to defer our understandings of biology (to philosophy) any more...
... which understandings includes artificial intelligence and consciousness as simply part of a solar system part of a galaxy part of being here and being there...

does mechanical apply to universe and cosmos...
...and for the mechanical free will to be...

But of course (some of us) we need splintered mind to comment, thanks...

Amy Kind said...

There are lots of interesting suggestions here. Thanks to everyone who has commented! I won't try to respond to everything, but just to pick up on a few points:
--I guess I'm just using "what's it like" or "something that it's like" in Nagel's sense, i.e., in his 1974 "What Is It Like To Be a Bat?" paper. I think that's also the sense that Eric has in mind in his work on garden snails. https://faculty.ucr.edu/~eschwitz/SchwitzAbs/Snails.htm I am happy to talk about qualia, or the qualitative aspects of experience, or phenomenal consciousness, instead. But I'm not sure if worries about "what it's like" talk are really worries about the expression or are instead skepticism about the reality of what that expression is usually taken to be picking out
--re: chinaphil's comment, I don't think that self-reflection is the same as "what it's likeness" but you may well be right that the capacity for self-reflection is necessary for consciousness
--re: Luke's comment, I don't think Stevland is presented as decentralized, insofar as I understand the notion of decentralized, but he is very very spread out spatially. He can act locally, though. In any case, the opening quote from HHM you use is a very interesting one. I'll have to think more about that.
--re: Unknown's comment, I happened to just be reading something else about fungi (raising questions about selfhood/individuality in relation to fungi). I think they're a really interesting case to bring to the mix.
re: various remarks, esp in Unknown and Gene's comments, I guess I don't see stimulus-response as sufficient to imply what it's likeness.
Again, thanks everyone for the discussion!

Philosopher Eric said...

Amy,
Many pathogens feast upon the epistemic meat of “consciousness”. Therefore as a positive professional in the field you’re charged with helping to ward these pathogens off so that science might begin to progress in this regard. To counter the “consciousness is amorphous” scourge I’d like you to consider generally referencing Schwitzgebel’s innocent conception. So powerful is this medicine that even the prominent illusionist Keith Frankish had to admit that yes, that sort of consciousness does actually exist (and even if he included rhetoric from which to claim that his movement is still right since no innocent conception can be substantive, which is bullshit.)

Like you I’m forced to agree with Maher that consciousness science is so primitive that we can’t say if a value dynamic exists for plants. I wonder if you’re familiar with Johnjoe McFadden’s proposal? Unlike what’s standard, this happens to be falsifiable, which is to say that good experimentation should demonstrate any validity to it. It posits that consciousness exists as certain elements of neuron produced electromagnetic fields. Therefore just as light is not lightbulb, consciousness is not brain — they require causal production from appropriate structures. His theory addresses the unified and serial nature of phenomenal experience, among other modern quandaries.

Mike (SelfAwarePatterns),
I don’t mind considering your conception of consciousness as something which has a self model, though I’ll need that fleshed out to assess any usefulness to it. What do you see as an extremely primitive variety of something that self models? Note that an extremely primitive variety of Schwitzgebel’s innocent conception of consciousness needn’t be functional — an experiencer would simply feel good/bad with no outward effect upon an organism. Or if you like you could call this a non-adaptive function of the organism. Innocent consciousness must have begun this way since evolution couldn’t have mechanized something that did not yet exist.

Luke,
McFadden solves Wu’s “many many” problem in the sense that an electromagnetic field exists as a single unified causal dynamic. I’m pleased that you’re interested in what the brain might do to create this sort of function (and beyond the presumption of a general panpsychistic “white noise”).

Anonymous said...

I understand Nagel’s question to be directed at the problem of how it’s like anything at all to be (for example) a bat. It addresses the classic problem as to how subjectivity, or the point of view of the experiencer, fits into a universe of matter. How do we reconcile subjectivity with the existence of a view of the experiencer from the “outside”?
At least in regard to some aspects of our own consciousness, it is pretty clear what those states are “like” compared to possible subjective states of garden snails or plants. But the more basic problem is how these states fit into a world of embodied objects.
Even if you could imagine what it’s like to be a plant, or a bat, that puts us no closer to resolving the classic “mind-body” problem.

Arnold said...

An update of "The Rise and Fall of Philosophical jargon" for this podcast might be useful...

https://dailynous.com/2018/05/08/rise-fall-philosophical-jargon-guest-post-eric-schwitzgebel/

...Biological semantics reaching to become 'philosophical jargon'...

Unknown said...

I liked this post, as well as many of the others at this site. I also very much liked the recent interview at Five Books.

Q: Would it be possible to include the post's title in the email notifications that go out? In that way, when I file posts I may want to revisit later, I could more easily find it. (Now that I think of it, I suspect I can search for keywords in my email. But, still, why not?)

LS

Howard B said...

How would your discussion gibe with Aristotle's classification of souls?
He said there was such a thing as a vegetative soul. If soul has something to do with consciousness, then he'd answer affirmatively to your question
Further, even if it is a collection of cells possessing consciousness, then perhaps there are cells in plants possessing consciousness.
I mean amoeba seem pretty lively and perhaps have an inner life.
Why not plant cells that seem more advanced than unicellular life

Amy Kind said...

Hi Howard, Thanks for your comment. I hadn't really thought about this in connection with Aristotle. I'll have to give it some further thought.

I guess I'm disinclined to think of amoeba as being (phenomenally) conscious. By liveliness, I take it you mean something like response to stimuli? But I don't take stimulus-response itself to be sufficient for consciousness.