How did minds first evolve out of matter? Could consciousness have evolved more than once? How can we tell which living things have minds? Is there something it’s like to be a crab and live a crab's life? This week we’re thinking about “Minds and Matter.”

Minds are a curious thing! Here we are, creatures of flesh and blood, but somehow we have conscious experiences. We perceive the world around us, and we have a sense of ourselves as agents that can move and act in the world. How do things like bodies possess these curious things we call minds?

I’m not going to attempt to solve the mind-body problem in this blog, but I do think whatever the solution ultimately is,both minds and bodies are going to be explained in physical terms. Minds and bodies are made of essentially the same stuff, and that goes whether we’re talking about an octopus mind or a human mind. Call the position that there is only one type of stuff in the world monism. Physicalism, the view that there is nothing above or beyond the physical world, is a type of monism.

Descartes famously proposed a dualist theory of mind. He argued that minds and bodies are fundamentally different substances. Minds (or souls) are essentially immaterial, pure consciousness, governed by reason, not mechanics. Bodies, on the other hand, are essentially material, physical stuff that is pushed and pulled by natural forces in the world.

In her correspondence with Descartes, Elisabeth of Bohemia wondered how minds and bodies could possibly interact with one another if they are so fundamentally different. Consider that Descartes argued that the mind, as a purely thinking substance, could not be extended in space (thus could have no location) and was not subject to the laws of physics. This was important because it was a way to account for free will. However, bodies, as pure matter, do occupy space and are subject to the laws of physics. So, how do bodies have any effect on minds, and how do minds have any effect on bodies?

This was a problem that Descartes himself admitted he could never come up with a satisfactory answer to. He did have an account of the pineal gland as the locus of interaction or “union” between body and mind, but this doesn’t help unless we can first answer the “how possible” question that Elisabeth raises about the mind and body's interaction with one another.

There are other problems with Cartesian Dualism—Descartes had a very strange view of nonhuman animals, and claimed that they had no minds at all. The term he used to describe them was “fleshy automata.” Nonhuman animals were basically machines in his view, which meant that they had no moral standing either. (Human bodies were also like machines for Descartes, but they formed a union with the soul/mind, which is why in the mid twentieth century, philosopher Gilbert Ryle described Descartes’ theory as “the dogma of the ghost in the machine.”)  

I’m going to hazard a guess here and say that Descartes probably never had any pets. I think it would be hard to spend any time with a dog, say, and not believe that dogs are creatures with minds, maybe not exactly like our minds, but minds nonetheless. In fact, the world is populated with a huge diversity of such creatures, and they all have lives that they experience first hand. There’s something it’s like to be a dog and to live a dog’s life. I may never know exactly what that’s like, but that’s not to deny the dog’s subjective reality. 

I don’t think it’s too controversial, even in 2020, to claim that mammals, at least, and maybe some birds, and some cephalopods, like octopuses, have minds, that they have experiences of the world. But what about fish? Or insects? Or a whole host of simpler life forms? Maybe Descartes was right about some animals being more like “fleshy automata.” Does a fruit fly have a mind, for example? This is where, I suspect, we will start to find more disagreement.

In order to answer a question like this, we need to know what exactly a mind is and what would count as evidence of one. Let’s stick with the example of fruit flies for a moment. They can do amazing things, like navigate mazes and track a moving target along the hypotenuse. Surprisingly, they’re actually quite smart. 

But what does it mean to ascribe smartness to something? In a world with smartphones, smart TVs, and smart fridges, “smart” isn’t saying all that much. We also talk about the intelligence of living things like plants, which can sense where the sun is and direct their growth in that direction, but that’s not to say plants have minds or anything like a mind.

So maybe what we really want to know about fruit flies is if they are conscious. Do they have subjective experiences of the world? Well, fruit flies, like us and unlike plants and cell phones, have brains. Teeny, tiny brains, of course, but brains nevertheless. So we might take this as evidence to consider. Maybe insects don’t have the kind of rich mental lives we humans have, but who’s to say there’s not something it’s like to view the world the way a fruit fly does? 

If we think the existence of a brain is important somehow, then we have to ask whether one is necessary for consciousness. In other words, if something doesn't have a brain, can it still have a mind? And we also have to ask whether a brain is sufficient for a mind. Could members of a particular species have brains but still never have conscious experience?

I suspect a lot of you think that a brain, or at least a nervous system, is a requirement for a mind. That’s a natural assumption to make. After all, it’s easy to see that animals like us—chimps, for example—have minds and inner lives. They are very close to us, evolutionarily speaking, and so we recognize their similar biology and similar physical form, as well as their similar social habits and emotional responses. Primates are our close cousins and they have brains very like ours. Non-primate mammals are part of the extended family, just not as close, but ultimately we all evolved from the same distant ancestors and there are many things we have in common with them as a result.

But think about other creatures that are completely different from us, that are related to us so far back on the evolutionary tree we find it hard to find much family resemblance at all. Squids, tardigrades, sponges! Just because they’re really evolutionarily distant doesn’t mean they can't have consciousness of some kind. Consciousness could have evolved more than once in the history of evolution, in different creatures with radically different physical forms, living in very different environments from us. We can’t simply assume that it didn’t anyway. And if that’s a real possibility, then we can’t assume that brains are necessary for minds, though they might be necessary for human or mammal minds. I believe that if we keep an open mind about this possibility, there are potentially many exciting discoveries that await us.

Our guest on this week’s show is Peter Godfrey-Smith, a philosopher who spends a lot of time underwater observing—and sometimes interacting with—all sorts of weird and wonderful creatures. He has a new book out called Metazoa: Animal Life and the Birth of the Mind, in which he recounts many stories about these experiences and uses them to draw important lessons about the evolution of mind(s), and what it means to be an animal with a subjective experience of the world.

Tune in this week for a great show!

Photo by novi raj on Unsplash