Do Plants Have Minds?

Plants don’t have minds. At least, that’s what most people think. A few years ago, that’s also what I thought. Then, reflecting on the work of Ruth Millikan and Fred Dretske, I started wondering why it seemed obvious, and whether it should. This led me to write a short book on whether plants have minds. The book isn’t for scholars, but instead for readers who do not have special knowledge of minds or plants. In it, I aim not to settle the question of whether plants have minds, but to nourish curiosity about it. Likewise, in this post, my aim is simply to clear some ground and plant that question in your mind.

Daffodil, by James Sias

Why might someone think that plants do not have minds? You might say that plants are merely alive, and being alive doesn’t suffice for having a mind. But why do you think that? You might say that bacteria are alive, and they clearly don’t have minds. But why are you sure that bacteria don’t have minds? You might say that minds require ideas or thoughts, which are essentially representations—inner pictures, sentences, or maps of the environment external to the mind—and plants don’t have representations. But—and this is what struck me a couple of years ago—several well-respected current theories of representation (such as those of Millikan and Dretske) actually imply that not just plants but all living things have representations. Furthermore, other prominent theories of representation (such as those of Wilfrid Sellars and Robert Brandom) that deny that plants have representations equally well imply that no animals, except for humans, have representations.

The belief that plants and most living things do not have minds seems to be a guiding constraint on constructing a theory of mind, rather than a consequence of any particular theory of mind. That is, theorists take for granted that an adequate definition of the concept of mind should exclude plants and most living things. If this is correct, then one can’t appeal to those definitions to justify the claim that plants don’t have minds, for that claim is based on a prior decision to exclude them in the first place. Such reasoning would be unacceptably circular. Instead, we need to ask: Why should an adequate conception of mind exclude plants and most living things? A good answer would be based on an accurate grasp of what organisms and non-organisms actually do, as well as on an adequate conception of life. Alas, it is questionable whether on the whole, theorists have indeed given such answers.

In the history of thinking about minds, people have struggled to do several things at once: ensure that at least (most, adult) humans have minds, admit that some nonhuman animals have minds, avoid inviting every other organism, such as bees, earthworms, and paramecia into the garden of the mind, and refrain from lumping organisms with non-organisms, sucking the life out of living things. These desiderata are hard to satisfy simultaneously.

In this respect, life has posed a challenge for thinking about the mind: Where exactly is the line between organisms that have minds and those that don’t have minds? Is there a line? What is the relationship between the organization characteristic of living things and the organization characteristic of things with minds? Following Evan Thompson (in his Mind in Life) and Peter Godfrey-Smith (in his Complexity and the Function of Mind in Nature) among others, we should cultivate the question of life for philosophical reflection on the mind.

A sly relative of that question lurks nearby: Why is it that, as far as we now know, only living things have minds?

For at least the past several decades in prominent English-language philosophical scholarship on the mind, there has been a strong presumption that non-living things at least could have minds. For instance, sufficiently sophisticated computers or robots could have minds. But even if that’s true, why think it shows that non-living things could have minds? Maybe any computer or robot that was “sufficiently sophisticated” would be alive, would qualify as being alive. For many scholars, this presumption seems to be another guiding constraint in constructing a theory of mind. But why should it be? Again, we might worry that the grounds for this decision are not empirically or conceptually adequate.

Yes, yes, fine, fine, you might be saying. Perhaps I have succeeded in planting the question in your mind. But what reason is there to think that plants really do have minds? In the next couple of posts, I will sketch an initial case for thinking that plants have minds.

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21 Comments

  1. Hi Chauncey, thanks os much for blogging this week. One thing I am wondering is whether asking whether plants *have minds* is really the best way to proceed here. That’s because I doubt whether the concept “mind” (or “minded”, etc.) actually picks out anything specific. So I’m inclined to prefer asking: Are plants conscious? Do they experience emotions? Do they perceive their environments? Do they act (voluntarily)? Are they social beings? And so on. Perhaps you end up treating a lot of these more specific questions. But in any case, do you think there’s a particular value in framing the overall project in terms of the possession of minds?

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    • Chauncey Maher

      Hi, John. Thanks for having me, and for the good question. I sympathize with the thrust of it. (I drifted off to sleep last night thinking that the concept of mind might have outlived its usefulness.) In the book, chapter by chapter, I focus on perceiving, feeling (qualia), memory, and voluntary action. Still, I think there is some modest value in framing the overall project in terms of minds. Roughly this: it helps non-experts into the subject. For that audience, your point is one of the first that should, I think, be made. ‘Mind’ is and has been said in many ways. So, in addition to being probably too generic, it also exhibits ambiguity.

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  2. Here’s a thought about life: it is a self sustaining biological or organic event. At least, all living things are constituted by cells and their functioning (or a cell and its function[ing]). While we may well ask whether this is a necessary condition, the onus of proof falls on you (or whomever wants to make the case) with respect to defending the thesis that being minded is sufficient for being alive.

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    • James Mattingly

      I don’t think you get to but “biological” into a definition of life. Maybe “organic” is ok, but organic doesn’t have much to do with cells as such. Also, viruses are probably alive, and they don’t have cellular structure. And it seems pretty clear that cells are evolutionary products of critters that didn’t have them.

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      • @James Mattingly Fair enough. I wasn’t careful. But, ostensibly, biologists have a good handle on what are and are not living things, and I meant to pick out the main sort of process that falls under their purview: genetic replication . (To explain my sloppiness: Viruses are often classified under the heading “microorganisms”, and I had assumed that viruses were single celled organisms because organisms are cellular. You are correct that they are not cellular, i.e. constituted by one or more cells, but, contrary to what you say about them, they are widely considered not to be living. But let’s assume that they are.)

        In any case, I will rephrase my central premise with respect to the more accurate theory you point to: something is living only if it has replicating genetic material.

        This premise abandons the requirement that living things must replicate or sustain themselves on their own, and I trust that there are no counterexamples to it. Now I don’t see that your comment has bearing on my argument renewed: Being minded is not sufficient for being alive unless it is also sufficient for having replicating genetic material.

        [Sorry about the delay in response. I failed not only to check my facts, but also to check the box which would have me notified about follow-up comments.]

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  3. Chauncey Maher

    Thanks for your comments, Nate and James. Nate characterized life in a way that is supposed to challenge my suggestion that mind seems to require life. He concludes that the burden is on me to show that it does indeed required. James, rightly I think, challenged that characterization of life.

    Let me add a little bit in response to Nate. My point was not that there is no definition of ‘life’ or ‘mind’ that would leave open the possibility that non-living things have minds. Rather, my point was that we should unearth and assess our reasons for preferring definitions of ‘mind’ and ‘life’ that leave open that possibility. In a question: should we prefer definitions that leave open the possibility that non-living things could have minds?

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    • Thanks Chauncey Maher, in turn, for responding to my poorly formulated concern.

      I understand that the focus of your query is primarily on the motivation for definitions of mind that allow nonliving things to have them. More specifically, I take (or took) the query to raise the question of whether being minded would be sufficient for being alive, because, at least, claiming that it is would be the most direct way to exclude the possibility of non-living things having minds. What I tried to do, then, was show that more motivation or argument (than what intuitions about the relevant concepts support) is needed to show that this latter question, whether x is minded only if living, is plausibly open and worthy of consideration. Why think that the central features of life as described by biologists are essential to the processes that we take to be definitive of mentation or cognition?

      My worry is that it is not plausible that being minded is sufficient for having what is necessary for life according to biology. I responded to James Mattingly above and understand that I can’t but give a slap dash characterization of life, but, as I point out there, it strikes very many people—biologists, primarily–that the central feature of living things is having genetic material and/or genetic replication.

      To clarify my worry about your stance, I’ll restate my developing foil argument:

      (1) Having at least some genetic material essentially is a necessary feature of living things.
      (2) It isn’t necessary to have genetic material essentially to be a minded thing, because, say, minds can be immaterial substances and/or non-organic things can carry out the processes that are definitive of mentation and cognition.

      So, being minded is not sufficient for being living.

      Premise (1) is of the sort that I took you to think depends on lazily adopted conceptions of mind and life. (Maybe your focus was more on calling into question everything that follows the “because” in premise (2)?) Either way, I think the idea that having some genetic material essentially is necessary for life in not a conception of life that it is at all lazy to adopt. In fact, it is one of the most corroborated hypotheses in the science that takes life as its subject matter. Moreover, I think making being minded sufficient for having the central characteristic of life is the most direct way of cutting out notions of minds that allow nonliving things to have them.

      Though, I suppose, scientists could have been lazy is figuring out what to study, my challenge comes down to this:

      The onus is on you to show (1) that being minded is sufficient for having genetic material (essentially), (2) there is some other way to show that only living things can have minds, or (3) that it is lazy to assume that having genetic material is essential for things to qualify as being living things.

      I agree that we should have good reason for assuming that (1)’s purported central feature is an essential one, a feature such that a thing cannot be living (or existing as a living thing) without. However, the possession of (replicating) genetic material is the least controversial feature posited to be shared by all living things in the life sciences. At least, I think the posit unifies much of the science, and, if so, calling it into question would call much of the science into question. It is a value judgment of mine, but the more science one calls into question, the more one should have a rational basis to do so–and probably one motivated by more than mere intuitions about the scope and limits of our concepts. Thankfully, you are doing more than that in this series of posts.

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  4. Evan Thompson

    Thanks, Chauncey, for the fine post, and everyone else for the discussion. My two cents:

    We need to distinguish between the minimal organization required for a system to be living and the question of whether that organization requires replicating genetic elements. According to the theory of autopoiesis, the minimal organization for life is that of a self-producing network of processes that generates its own boundary as a necessary part of its self-production. It is not a necessary feature of such a self-producing organization that it also be self-reproducing or that it contain replicating genetic elements, though of course these additional features belong to all life as we know it now on Earth.

    There are early life scenarios in origins of life research in which the first autopoietic proto-cells were not able to self-reproduce and did not contain genetic material. This is also a working scenario in synthetic biochemistry (the effort to create such proto-cells in the lab). For an excellent state of the art treatment, see Luigi Luisi’s book, The Emergence of Life: From Chemical Origins to Synthetic Biology: https://www.amazon.com/Emergence-Life-Chemical-Origins-Synthetic/dp/1107092396/ref=dp_ob_title_bk The idea is also widely explored in computational artificial life research (see this 2004 issue of Artificial Life: http://www.mitpressjournals.org/toc/artl/10/3 )

    In my book, Mind in Life, I argue that life is sufficient for mind (and hence mind is necessary for life); the question of whether mind is sufficient for life (and hence life is necessary for mind) is tricky, but a case can be made: see my response to Michael Wheeler in this symposium on my book: https://evanthompsondotme.files.wordpress.com/2012/11/thompson_reply_jcs_author_proof.pdf

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    • Thanks very much for these interesting cases! I had just a passing interest in this topic area when I clicked on article from your Facebook feed. But my involvement here and the intrinsic interest of the subject is leading me to think about getting rid of my ignorance.

      (Nate Bemis)

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  5. Monica

    Nate, regarding your statement “non-organic things can carry out the processes that are definitive of mentation and cognition ” — I assume you mean AI. Would you say that mind could be considered a side effect of such processes? In other words, could these processes “cause” mind? In the case of AI, this might open an interesting avenue of looking at mind as something separate from consciousness, which, in agreement with Searle, I believe lies outside a mechanical / neurological framework — hence the “mystery” of consciousness. Exploring the definitions of mind and consciousness as well as their relationship is fascinating of philosophical enquiry, for sure.

    Actually, what I really wanted to contribute is my 9-year-old’s instantaneous, intuitive comment when he read the title: “Of course plants have minds. Otherwise they wouldn’t be able to do anything, not even die.” Is dying a voluntary action that requires mind?

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    • Again, I was being sloppy. AI, but also possibly possible non carbon life forms, life forms with different biochemestry than ourselves. But, if such things are possible, then there could be a problem with my statements about what is constitutive of life if genetic material is essentially carbon based.

      I agree that the problem of consciousness is the most difficult area for unifying our account of mind with the rest of science, i.e. the area where physical or computational terms and theories seem to have the least bearing. My inclination is to ditch notions of what its like to be a bat or for you to taste a strawberry, etc.

      I don’t know if I can do that rationally, for I do seem to have experiences that cannot be observed by anyone but me. Perhaps, issue with quantifying consciousness is more that we have no instruments but our own consciousness for ever “directly” accessing it than that that it is forever outside our universe. I can rationally say, however, that I am taken by accounts, such as Peter Carruthers’ in The Opacity of Mind and The Centered Mind, where we do not have direct access to our own mental states. (There is wiggle room here, however, for saying that though we can only perceive our own mental states through sensory experiences–the thesis defended in these two books, what it is like to have these experiences is the uniquely subjective phenomenon that is not apt for assessment in physical, quantification, or other non-mental terms.

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  6. João Vergílio Gallerani Cuter

    I was wondering about the difference between the question you make and a much simpler one: do we have any practical reason to extend the conventions for the use of the word “mind” to plants? Do we have any reason to make this DECISION as to the use of the word “mind”? At the end, is it not merely a question of DECIDING what criteria we are ready to accept to apply the word to a real or imaginary case? After fixing a criterium, is it not both easy and natural to admit that there are border cases where we simply do not know if our (new or old) criteria should still be applied to? I don’t realize what ELSE you want to know in addition to this. You seem to have a question that goes BEYOND the mere convenience of making a decision about the use a word in a given case. But I am not able to realize the nature of this “plus”. You would probably say that you start from a theory of mind – a theory about the “nature” of the mind, and that this theory has nothing to do with conventions. What is the independent ground on which you are walking? Is that ground enough to say that conventions SHOULD be made this way or that? Thanks for your thoughts.

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    • Chauncey Maher

      Thanks, João. I think I understand what you’re getting it. Putting it differently, I initially asked, “Do plants have minds?” You wonder instead: Is it useful to say that plants do (or do not) have minds? That sort of question would commonly contrast with one like this: Whether or not it is useful, is it true to say that plants have minds? Framed that way, we are very close to discussing theories of truth. Without yet defending any such theory, I’m comfortable regarding your question as a version of my own. That is, I think we should indeed consider whether it’s useful for us—as students of plants and minds, but also as people living amidst and dependent on plants—to say that plants do (or do not) have minds.

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  7. Benjamin Saubolle-Camacho

    I haven’t read any later posts, but an initial response:

    The “robot-as-possessing-mind” argument seems more like a semblance of a HUMAN mind than of an objective understanding of mind.

    If anything, your puns were all I needed to grow the seed of thought that plants may have minds.Reference

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  8. PeterJ

    You raise a good question. It is not clear to me why we should assume that plants do not have minds and a state of consciousness, nor why we should assume that robots ever will.

    There is an even deeper questions, which is whether plants are mind. That is, whether all that we see around us is a mental phenomenon as Kant suggests and evaporates for any reduction of mind, plants ‘n all.

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