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.