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.
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.