The Second Cartesian Error: Inability to bridge the gap between physical and mental

Descartes’ basic position in the Passions of the Soul is that the emotions are cognitive because they are activities of the soul or mind. One of his problems is distinguishing between other abilities or activities that could seem cognitive, like sensations and perceptions, which to him are not cognitive because they are activities of the body; they are always either focused on the body or objects outside the body.

After all, he thinks, any time you sense something, it’s either your body you sense, or some other object in the world. But you don’t sense your mind or your thoughts. He thinks the same goes for perceptions. In fact, in his earlier book, Meditations on First Philosophy, Descartes said perception was ‘non cognitive’, because it provided little more than basic ‘shapes’ for the soul to interpret. However, he does change this in view in quite important ways in Passions of the Soul, and it will seriously affect his conclusions regarding the emotions.

The physical aspect

On Descartes’ account emotions happen in the soul, and therefore are “psychic events”. However, he also explains that they have a physical basis. Though the details of his physical account are now hopelessly wrong, the general idea was pretty interesting and we need to have an idea of how it works to see how he gets in trouble reconciling the physical and mental aspects of emotion.

Descartes explains that emotions are caused and continued by chemicals, which he calls spirits, coursing through the body. These spirits can literally cause the soul to move by flowing to and moving the pineal gland, where he thinks the soul sits in the body. The soul feels the pineal gland move, and these chemicals and movements are also how the soul is presented with images and ‘shapes’, for example, of a bear. If the souldetermines a particular shape or set of shapes to be frightful, it excites the soul into a state of apprehension. This is not itself an emotion, such as fear, but the soul needs to be in apprehension for it to develop an emotion.

The soul will develop an actual emotion based on three factors, any one of which can be the determining factor in what specific emotion develops:

1. The natural temperament of the specific body (your body, mine, Descartes’, etc)
2. The strength of the soul (how naturally strong your mind is)
3. Previous success in dealing with the thing, or similar things, by defense or flight. (learning from memory)

The cognitive aspect

Descartes explains that similar to perceptions, which are not actions of the soul or willed by the soul, emotions are thoughts that happen to the soul. Only what the soul itself wills, what it does, is full on thinking. Knowledge only comes from the soul acting, not being acted upon. Basically, an act of willing, what he calls a volition, isdirectly caused by the soul itself, whereas the proximate cause of the emotions is a specific agitation of chemicals. At the same time, just because passions are received into the soul just like perceptions and sensations doesn’t make them perceptions and sensations; emotions are way stronger. In fact, he argues that nothing can excite the soul as much as the emotions. Given this dual physical and mental aspect of emotions, Descartes sails into some choppy waters trying to explain what sort of psychic events emotions are, and his theory sinks

The problem

You’ll remember that the fundamental thesis Descartes wants to defend was the emotions are of the soul, but in the way he sets about explaining how they are accounted for physically, he’s inadvertently – inescapably – set it up so that they can be completely physically explained. This is a disaster and will take another post to fully explain, but let’s get started on the basics.

In the ‘physical aspect’ section above, we learned that experience can predispose the brain so that chemicals hitting the pineal gland flow directly into one or more of three parts of the body such that in every emotion, some particular movement of the proper chemicals in the brain is the principal cause of that emotion. These chemicals do not contain any ‘mental content’ such as thoughts or judgements, instead they simply make the soul to feel. And as we’ll see next time, the system as he describes can totally bypass the soul and create emotions of all kinds based simply on memory, perception and natural born tendencies in you.

To escape this conclusion, Descartes has to commit the Second Cartesian Error. He must insist that these coordinated actions are not really emotions, but emotion-like behavior. An immediate problem is that the behaviors we’re talking about, for example feeling a cold sweat, your stomach in knots, turning and running, etc are more complicated than other clearly non-mental activities such as breathing, swallowing, blinking, or even absentmindedly walking about. 


If we can be show that these behaviors do have mental content above the ‘shapes’ of simple perception, Descartes would seem forced to accept that in some sense the soul is involved in them. The thing is, because of how he’s defined things, he only has two choices for what to call the behaviors, volitions or emotion. Since the soul does not choose to do these physiological things, they can’t be volitions. That only leaves emotions. But then the soul isn’t really involved in emotions.


To avoid this result, he has to accept that these behaviors caused ‘merely’ by memory, perception and natural born tendencies are emotions. Even if they have nothing really to do with the soul. But then, on his theory, they can’t have any ‘mental content’ or ‘thoughts’. The only other option is to admit a contradiction, which of course is no good either, so he needs to find some way out of the dilemma.


 In short, his great interest in mind-body dualism says emotions must be mental, must be of the soul. Yet he created a mechanism to explain the physiology of what happens to us in emotional states that makes this unnecessary. We’ll finish this up next time.

The Second Cartesian Error and a discussion of Ad Hoc Hypotheses

I also told you that the Second Cartesian error is the irreparable separation of emotion from thinking, which forces Descartes to make up a way to sneak intelligence into emotions once he realizes he’s made it possible for emotions not to involve the soul. Over the next couple of posts, I’ll explain why it’s a very bad mistake, but I'll begin by saying that I started this whole project with the plan to show that it is incorrect to separate emotions from cognition.

I say its incorrect because I think emotions and emotional behavior clearly demonstrate thinking or cognition. And in previous posts I fleshed out a theory, which I called P-A-L, that treats emotions as a type of cognition while also accounting for the fact that they are also physiological phenomena. I also explained how Stoicismrose to challenge that theory and put forth the competing idea that the emotions are purely mental phenomenon, purely thought and have nothing to do with the body. Descartes’s goal is to further this project by adding a highly sophisticated attempt at a scientific look at how the body works. You could even go so far as to say that when it was written, Descartes theory of the emotions was state of the art for science and medicine at the time. Because of that, and even though it is hopelessly wrong in the specifics of physiology, we need to get some familiarity with what he thought was going on.

Earlier, I explained why it was a mistake for Descartes to completely split mind and body the way he did, calling it the First Cartesian Error. But if you think about it, its really two separate errors in one decision. Consider that though Descartes decided that only the mind could think and could do nothing but think, he could have argued for a split that did more sharing of cognitive abilities. Unfortunately, the way he chose to do it splits emotion from cognition or thinking. Enough background, let’s start unpacking the Second Cartesian Error.

Descartes ties himself in knots trying to maintain his strict mind-body dualism while at the same time trying to explain the physiological aspects of emotions and emotionally charged actions. To get out of the knots he has to find some way to imbue emotion with intelligence, since they are supposed to be “of the soul”. Unfortunately, his solution is ad hoc.

What’s an Ad Hoc Hypothesis?

An Ad Hoc hypothesis, claim or distinction is the use of an unsubstantiated claim or hypothesis to defend your preferred theory or explanation from fact that contradict it. I’ll give two examples, one where its easy to see that an ad hoc hypothesis is being used, and that it is unfair, and another where it is unfair but is harder to see at first.

Easy case

Imagine the following argument between Sue and Tom:

Tom: Sue, I’m going to use our last $20 bucks to play roulette because I know what the winning number will be.

Sue: I wish I could agree, but there’s no way to predict the roulette and the odds of winning are so low that it’s really a waste of money. Let’s just go get a drink and call it a night.

Tom: (Bets on roulette and loses)

Sue: See, I told you you can’t predict a winning roulette number.

Tom: I only failed because you didn’t have faith in my ability. Your negativity made me lose focus and obscured by vision.

Sue: (Rolls eyes and sighs).

As you probably already get, Tom’s argument has problems. First, there is no way to prove that lack of faith or “negativity” caused him to fail. Second, his argument doesn’t even really address the facts Sue’s criticism depend on– games of chance such as roulette are basically random, there’s no skill involved in guessing the outcome; and there’s no credible evidence for clairvoyance. Tom says nothing about how he might be able to pick numbers, so there’s no reason to believe him in the first place. But given that he does believe in his ‘ability’, when it doesn’t work out, he’s the one who needs to explain why. In this case, he simply makes up a reason why he wasn’t wrong about his ability. A reason that can’t be tested and that doesn’t even address the criticisms of his theory.

Complicated Case

Imagine the following situation:

Sue asks Tom to pick up a 6-pack of their favorite beer from Seller Bob’s on the way home. Tom meant to but got caught up listening to his favorite podcast and arrived home forgetting to grab the beer. Sue asks why he didn’t go to Seller Bob’s and since he was afraid of making her mad, he lied and said he did go, but that they were out of the beer. That is, his explanation for not having beer is “I went but there was none”.

Sue was confused by this because she’d called Seller Bob to make sure they had the beer just before calling Tom with her request, and the manager assured her they had plenty. She explains this to Tom and Tom realizes that while his explanation is now in some doubt, it’s not clearly false. So he tells Sue that what probably happened was that a bunch of the local college kids probably swarmed the place and grabbed all of that beer before he arrived. So he’s changed his explanation to “I went, but I others beat me to it and when I arrived there was none.” Now, if Sue was sufficiently upset or skeptical of Tom, she might go to the store herself and see if there was any left, and ask about recent sales. Or she might just not care enough and move on.

So why is Tom guilty of ad hoc arguing? He wanted to get the beer but failed. He wanted to hide his mistake so he offered a hypothesis about why he didn’t have the beer. His story might have been true but Sue came up with a strong objection to it. One that didn’t disprove it, but that required more evidence for the theory. Tom takes Sue’s objection and makes it a part of his theory, he adjusted his original theory in the face of objections. This isn’t wrong on its own, but in this case, Tom knew the theory was probably not factually true, and that he only put it forth because wanted Sue to believe it. However, even if Sue accepts his new theory, it doesn’t take away the fact that he simply made up the explanation of the afternoon’s events.

Here’s a good website discussing ad hoc hypotheses if you’d like to read more. We’ll stop here for now and next time we’ll work to understand Descartes’ theory and what I argue is his ad hoc attempt to save it.