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Mind Matters

Do beetles make decisions? Do slime molds solve mazes? Do plants learn?

In my new book, Pieces of Mind, I examine the possible ways to interpret what psychological terms mean when biologists use them to describe a wide and growing variety of nonhuman species … and argue the best answer to each of these and similar questions is a literal “yes.”

Psychology is transitioning toward a non-anthropocentric way of understanding nonhuman psychological capacities, with important implications for how we justify the superior moral status of humans.

What inspired you to write this book?

I was thinking about how psychology and neuroscience are being integrated to give us a single (if complicated) story of how the mind and brain are related—the old “mind-body problem” updated to the 21st century. The leading philosophical theories of this implied that psychological terms would appear at the top, so to speak, when talking about human agents (and presumably at least some other species), but that as we progressed in the explanation we would just be talking about the activities of neurons and chemicals and so forth. In other words, the psychological language would give way to neural (or, broadly speaking, physical) language. And the more I looked, what was curious was that this did not seem to be happening at all. Instead, I saw psychological language being used more, not less, to characterize not just neurons but also many other species who weren’t really considered to have much, if anything, in the way of minds. Many of us are aware of recent discoveries about bird intelligence, or octopus intelligence, or whatever new species is being investigated. But what many people are not aware of is that these publicized examples of new discoveries in nonhuman intelligence are just the tip of the iceberg: we now have plant cognition, bacteria cognition, and so on with new papers being published all the time. And so this led me to realize that there was this big question that needed to be asked: How should we understand what psychological terms mean when scientists are using them to describe their discoveries in all kinds of nonhuman domains? For example, do fruit flies really make decisions? Or are we using the term “decision” in these and other cases in a different way than when we use it for humans? So the book came about as a result of my desire, first, to make sure this question would be asked, and second, to defend what I think is the best answer to it.

What’s at stake for science regarding this issue you’re tackling?

This depends on what you think the best answer to the big question is. For example, if you think talk of minds in birds and bacteria and octopi and plants and so on is metaphorical, then nothing is at stake for science, except maybe that we should be worried that many research scientists are increasingly waxing poetic in their professional publications and presentations. However, if you think the talk is literal, as I do, then they are acting quite rationally. That’s a nice result.

There are other significant benefits, too, of my view. It promotes theoretical and empirical investigation by making cross-species comparisons more reliable and less vulnerable to misinterpretation. For example, whenever we use animal models of depression, PTSD, and other psychiatric conditions, there is a related question of how we should interpret the psychological language. (Is “fear memory” the same capacity in humans and rats?) It opens the door to using a wider range of model organisms for psychological studies, which can be practically important. It contributes to ongoing debates about the nature and extent of animal cognition as well as group cognition by providing a new framework for understanding mental attributions to other animals and to groups. It helps us avoid explanations of the mind/brain relation that introduce mystery, rather than dispel it, by making human minds appear unique in some way beyond the fact that every species is unique. It also reframes the way we should explain the behavior of humans and nonhumans, promoting a convergence in the types of explanations that are best—it’s no longer the case that human behavior must be explained with high-powered cognitive machinery while animal behavior can only be reflexive. That gap is getting narrower for independent reasons, and my view helps to bridge that gap from a conceptual standpoint.

What’s the takeaway for readers?

In my view, we are in a period of significant psychological-conceptual transition—we’ve pretty much thought of human cognition as the standard for all cognition, with the result that when we use a psychological term (e.g. “deciding”) for a nonhuman, we tend to think its capacity isn’t real or full-blooded.

I think this traditional, anthropocentric science of psychology will be, and is being, replaced by a science of psychology that does not rely on human cognitive capacities as the standard for what a cognitive capacity is. Notably, this view is already accepted for perception: for example, vision is vision whether the visual system belongs to a human or an eagle or a mole. We also recognize that human vision need not be the best kind and no one’s nose gets out of joint. But once you start talking about thinking (cognition), our attitude changes drastically—other species are never as good as we are, and it’s extremely important to us that they aren’t (cue here all the hand-wringing about superintelligent AIs).

It doesn’t follow on my view that we aren’t “best” at cognition, or at least some forms of it (readers may have seen that fascinating video of a chimp who can remember where numbers were flashed on a video screen far better than the humans in the experiment). But this would be a matter of further investigation. We should be able to formulate a psychology that does not presuppose that human mental capacities are the standard for (and of course superior to) any others in the natural world. This has implications for how we treat nonhumans, given that we have traditionally based our superior moral status on having a superior mind.

Can you talk about how yours is the “first book to examine how mathematical models provide an important new kind of evidence for mental capacities in nonhumans”?

The upshot of this claim is that mathematical models are a well-regarded scientific method that is now being used to provide evidence of when an entity has a psychological capacity, and in addition that evidence is not affected by our anthropocentric biases. That’s very important, because before these recent methodological developments we could only look at other species and their behavior through a human-colored lens, so to speak. Achieving this sort of objectivity is not a problem for physical evidence; we can look at neurons across species and compare them without any worries about bias. But when we judge that an animal is stupider than we are, we inevitably use a non-neutral standard for comparison: “Can they do what we would do in that circumstance?”

Consider how you know that anything besides yourself has a mind. Our main source of evidence has always been behavior: If you behave like I do, and I know that my own behavior is caused by my thoughts, I’ll infer that you have thoughts that explain your behavior too. (I pack an umbrella, for example, because I think it’s going to rain later, so if I see you pack an umbrella, I’ll infer that you also have thoughts.) We ascribe mindedness automatically to each other in this way, and only philosophers question the reliability of that inference.

Obviously, when we consider other species, this type of evidence is not so great. We also use physical evidence, especially if a type of creature has a brain, and in the light of what we know about its evolutionary history. For example, even without knowing the whole story of the mind/brain relation, if the human hippocampus is involved in human memory, and we find that rat brains have hippocampi, and we find that lab rats act as if their memories are wiped out when their hippocampi are removed, that’s decent evidence of a memory capacity in rats. None of this evidence proves (deductively, with certainty) that the other creature has a mind—for all I really know, you might be a zombie—but it’s the best we’ve had.

Now, however, we have mathematical models that capture patterns in the behavior of humans and nonhumans alike, patterns that we might not otherwise have observed or discovered to be importantly similar. These formal models provide a neutral means to obtain evidence of whether a nonhuman species has a particular cognitive capacity: When the behavior captured in the model is typically used as evidence for saying that a human has a specific capacity, and the model captures the behavior of members of a nonhuman species, that’s a reason to think that species, too, has that capacity. It doesn’t settle the matter, but we no longer have to rely on evidence that depends on interpreting that behavior guided only by intuition (and prejudice) about nonhumans and what they can do. To me, having a non-human-centered source of evidence for other minds is a revolutionary development.

What do you find most fascinating about your work and field?

The sort of philosophy I do is very integrated with the relevant sciences, and this is a relatively new and exciting development within the discipline of philosophy—it might well be described as theoretical psychology. In addition, cognitive psychology and our understanding of the mind/brain relation are in an amazing period of growth and change, partly due to new techniques for exploring neural function in awake humans and nonhumans, partly due to the use of computers and new mathematical tools for modeling various aspects of cognition in silico, and partly due to greater general awareness that the nonhuman world merits investigation without the bias of presupposing that nonhuman behavior is simple, stupid, and hardwired. It is a great time to be an “empirically-oriented philosopher of mind,” as philosophers of my ilk are also sometimes called.

Anything else?

The book is intended to prompt debate about the implications of cutting-edge biological research for our understanding of psychology. Of course, I also think the view I defend is the only serious contender once you start thinking about it, and as such should not be controversial even if it is surprising (as are the research practices that need to be explained). The implications of my view for how we treat ourselves in comparison with nonhumans, and how we explain what minds are, are much more controversial, and I’ll be considering these implications further in future work. And I haven’t said anything about artificial intelligence; that’s a further topic I’m thinking about in relation to the general issue of how to understand psychological ascriptions to nonhumans.