Mind and Body:
From René Descartes to William James

Writing Descartes:
I Am, and I Can Think, Therefore ...

Story Evolution

an exchange triggered by Grobstein's Writing Descartes ...
13 July 2004

Raimy followed by Grobstein

Dear Paul,

Since we're writing letters, I'll assume the form then. I agree with the impetus behind your letter to our friend René. My perspective is that you're right in that we have placed too much importance on the "I think" part of René's famous line. I also agree that skepticism is a very important tool for inquiry and that's why I'm a little worried about the burden put on the "I think" part.

In my mind, "thinking" has not felt the full brunt of skepticism. We as humans think but other animals probably do not and plants definitely don't is an all too common theme. But how do we really know this? In conversations that we've had in the Language Group, we've owned up to the fact that one individual can not be sure that there are thoughts in another individual's head and this holds of humans. At this point, the best case scenario is that an individual could only be sure that they think.

This just goes back to what "thinking" is. If we go back to a less stable position and grant that all human beings think but no other animals (or other biological entities in general) do, we must be skeptical of this dichotomy. To put it simply, how do we know that "thinking" is any different than sensory input? We could try to stake out a position that "thinking" is some sort of internal process and sensory input is necessarily dependent on external stimulation but I don't buy this. My sore legs from riding my bike too much yesterday seems to be an internally sourced sensory input. This must be internally sourced if we (correctly in my mind) abandon the "mind/body" split. If the 'mind' is the 'body' (i.e. brain) then the cut between 'external' and 'internal' should based on the limits of the body. So maybe "thinking" is just internal sensory input? Maybe, we're just sensing ourselves when we think?

At this point my skepticism raises the following question: If "thinking" is just internal sensory input then why don't animals and plants and other biological entities "think"? Following this line of thought some might argue that plants (and some of the more simple animals) do not have the same type of nervous system that humans do. You were talking about trees in your letter and this is an example of where we could try and draw a line. Trees don't have a central nervous system like animals do and consequently trees don't think. This just reinstates the 'mind/body' distinction though. The 'mind' is the CNS thus entities that don't have a CNS don't "think". Returning to this position actually helps my above sore legs example because we now have an internal/external cut based on the CNS. Sore legs are internal to the body but not internal to the CNS because it is the muscles with too much lactic acid causing the inflammation of the CNS which I perceive as soreness.

Continuing my rambling and skepticism: elevating the CNS to the level of 'mind' in the Descartean dichotomy only raises questions. If we again look at trees and plants in general some might be surprised at how complicated their behaviors are. Some might question whether plants have behaviors but I think this is just an artifact of wanting to separate humans from such 'simple' entities. Plants react to the external environment which is a reasonable definition of 'behavior' in my mind. Sunflowers turn through the day to always face the sun. Roots grow down into the soil in search of water and nutrients. Plants go into 'hibernation' (or whatever the plant based name for this behavior is) when faced with drought or other harsh environmental challenges and reawaken when the environment is favorable again. The interesting thing to these observations in my mind is how to understand this complicated behavior in an entity that doesn't have a CNS. The plants that show these types of behaviors must be getting some sort of input from the external environment and there must be some sort of internal regulation of the responses. How can we be sure that this 'internal regulation' is not "thinking"?

On the topic of internal regulation, we can go back and get skeptical on the special status of the CNS that I proposed earlier. As your own work has shown, the CNS can be separated from the brain and yet still show some very complex behaviors. How are we to understand this? Since the CNS is separated from the brain, it doesn't "think"? Or, have we separated "thinking" from the brain altogether? Is the separated CNS a really complicated plant? We can see where the questions go from here.

With all of these potential problems with "thinking", maybe we should try an approach where "thinking" is not a primitive but is instead a derived feature of an entity. Here is where I want to tweak your new and improved Descartean proposition: "I am, and I can think, therefore I can change who I am". A more useful approach in my mind to this proposition is the following:

be + change = potential thinking Here are my ideas around the modification. First, let's use the word 'be' instead of 'I am'. 'Be' is tenseless which encompasses all of time or none of time depending on your view of things. I think this is the simplest possible assumption in that it captures the idea that 'there is something here' with the least amount of baggage possible. If you can find some baggage to unpack here, I'm more than happy to jettison it. 

The second important part is the idea of 'change' which is derived in your statement. I'm cheating here just a little bit because I've spoken with you about the letter before finishing mine but some things are unavoidable. All things change. Even the entities that we refer to as the 'active inanimate' so this is an important part of any equation that we propose. The important part of 'change' though is whether the entity under investigation can notice it. Rocks and other 'active inanimate' entities presumably do not have any organization to them to notice change. In other words, even though rocks are constantly changing due to erosion and the general effects of entropy, they don't realize this. Thus, since rocks are not aware that they are changing, they do not "think". This type of example is why I want to start from 'be' and not 'I am'. Being able to state 'I am' suggests that the entity is aware of change because 'I am' implies the possibility of 'I was' and/or 'I will be' which all require the ability to notice change.

Moving onto more complicated entities, we can now attribute "thinking" to insects because they show adaptive behavior based on changes. The type of example I'm thinking about is Gallistel's discussion of the work on animal locomotion. Specifically, the experiments on six legged insects where you cut off two of their legs. The short summary of this work is that the behavior for six legged locomotion can be changed into four legged locomotion by simply altering the phase of the motor control program. Put another way, insects show rather sophisticated intelligent behavior because they can adapt their locomotion behaviors instantly when you cut off two of their legs. The insect has noticed a change and has altered their behavior accordingly. Some might become uncomfortable at this point because I've now claimed that insects "think" but this is just the right direction to go in in my mind.

The simple modification to your proposal I made allows us to now investigate "thinking" as opposed to assuming it. There are many important and interesting questions that arise now. Some of the more fruitful questions that we can ask are how the sensitivity to different changes produces different types of "thought". We can begin to see why we've fallen into the 'human supremacy' trap because maybe humans are the most sensitive entity to change at this point in history. More sensitivity to change in the ability to track and notice different internal and external changes may be the source of our 'high' level of "thinking". We can also envision how specific entities may have 'higher' levels of "thought" in specific realms due to their better ability to notice change. I'm considering how to conceive of 'dog thought' in the realm of smelling things. Dogs have a much more developed sense of smell in that they can track changes better than humans can. I would be very comfortable in giving dogs more complex "thoughts" about olfactory events than humans have based on this difference.

Well, I've gone down the rabbit hole far enough with these thoughts now. So what do you "think" Paul? Or to let me rephrase this according to my proposal. I've changed your ideas around a bit, I'm sure you notice this change, what "thoughts" have resulted from them?


Dear Eric,

Thanks for taking the time with this. I agree there is something slightly odd in interrupting ongoing conversations and "slicing" them into letters at a particular time. As you say though, "some things are unavoidable" and "slicing" at particular times may even have some benefits for promoting "change" ... which you usefully emphasize and which I agree is indeed the bottom line. Yes, of course, you've changed my ideas "around a bit" (it can't be otherwise in engaged conversation), so let my sketch resulting thoughts for whatever they might do for you in turn.

It is, I think, entirely appropriate (indeed desirable) to be skeptical about "thinking". And in this context it is indeed relevant to point out both that the term almost certainly means different things to different people and that if one means thinking as "internal experience" one has no way to be certain that another human being has it, much less to be certain whether other entities (cats, trees, rocks) do (or not).

With this acknowledged, I have found it useful (and still do) to make a distinction between rocks, trees, and people. People seem to me to have (at least some of them, sometimes) a capacity to "conceive themselves (and other things) as other than they are". It is this that I would call "thinking". It is closely related to what you call "aware of change", and perhaps even the same thing if one changes that slightly to "aware of the POSSIBILITY of change". And my sense, like yours, is that rocks don't have it. There is just nothing in what I observe of rocks that even hints (for me at least) that presuming internal experience would help me to understand them better (predict their behavior better than I can without presuming it). On the other hand, my experience (so far) is that presuming internal experience does help me to understand humans better (in the same sense).

Where things get trickier for you and me (and, I suspect, most people) is in the range of trees, insects, and dogs. I observe all three to be doing things that, if I reflect on them to varying degrees, seem to me quite remarkable and sophisticated (how DOES a tree make itself out of a seed?). I certainly would have to "think" (consider various possibilities other than what I currently am) to do those things, and so its an easy step to presuming that trees/insects/dogs must "think" in order to do them as well. What a century of work in biology, and thirty years or so of "complex systems" research have clearly shown is that is not in fact an appropriate step to take. Very sophisticated behaviors can be accounted for readily in terms of quite simple assemblies of matter, assemblies in which there is no sign whatsoever of anything that would constitute or provide a capacity for the assembly being able to "conceive itself as other than it is".

So, can we distinguish among trees, insects, dogs, and people in terms of "thinking" in the sense you and I (and Descartes) are using it? The issue is not "sophisticated" behavior nor (as in insects) detecting a change and responding to it (which, incidentally, trees also do). The issue is the internal experience that allows one to conceive of self/other things as other than they are. Its at this point that some comparative neurobiology is relevant. Humans have a particularly complex nervous system that can be usefully subdivided into two parts. Damage to one part (the "neocortex") affects "internal experiences" in various ways while, frequently, leaving relatively undisturbed a variety of aspects of sophisticated behavior apparent to an external observer. For this reason, taken together with a number of related observations, it seems likely that the neocortex is what gives us the capacity to "think" in the restricted sense in which we're currently using the term.

IF one chooses to follow this line of argument, it provides a way to begin distinguishing trees, insects, dogs, and people (to, in your terms, "investigate thinking"). Trees have nothing comparable to a human nervous system, and so are unlikely to "think" in the narrow sense, despite being very sophisticated actors/responders in other ways. Insects have a nervous system but nothing close to the particular kind of complex architecture associated with neocortex in people; so they probably don't "think" either. At this point, things get a little muddy. Frogs have nervous systems quite comparable to our own EXCEPT for the absence of a neocortex, and so probably don't "think" in the sense of having internal experiences. Dogs (and all other fuzzy animals, ourselves included) have basically the nervous system of a frog with a neocortex added, so one might find varying degrees (and, as you suggest, kinds) of "thinking" in this set of organisms. The important (and open) question is how to identify/explore these different forms of "thinking".

Hmmmm, that's work for the future, so let's back out of THIS particular "rabbit hole" a bit. Bottom line is that I'm disinclined, for the above reasons, to attribute thinking (in your "high" level sense) to either trees or insects. And, for this reason, I'm also disinclined to define the key issue as SIMPLY "change" or even "the ability to notice change". Change, as you say, is an attribute of rocks ("the active inanimate"), detecting and responding adaptively to change is an attribute of trees and insects ("model builders"). What "thinking" ("story tellers") add on top of this is perhaps "being aware that they are changing" or, in my terms, being able to conceive self (and other things) as one possible thing among many. Actually, that sort of appeals to me, how about you?

One final issue, for the sake of the record: your sore legs and mind/brain/body problems. There is indeed an external/internal cut based on the limits of the body but, for most purposes, the more important cut is based on the limits of the nervous system. The experience of sore legs is a pattern of activity in the nervous system, probably specifically in the neocortex, that is, as you say "sourced" to the body. This pattern may be triggered by a pattern of activity in sensory neurons that is in turn triggered by changes in your leg. But it can also arise from activity generated largely or entirely within the nervous system itself. Signals going to the neocortex come exclusively from other parts of the nervous system (rather than from sensory neurons). Hence experience (mind) may reflect inputs from other parts of the nervous system which may reflect inputs from other parts of the body (which may reflects inputs from outside the body). That help? Concentric circles, like an onion: neocortex (mind) inside of nervous system inside of body inside of world. Remove neocortex from the rest of the nervous system (not CNS from brain, brain is a part of the CNS) and yes, one gets (I think) a "really complicated plant" (lots of doing but no "thinking").

Assume we'll have both more conversation and more slices in the future. As always


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