This essay will be delving deeper into Anthony Gottlieb’s article The Ghost and the Princess which explores Descarte’s substance dualism and the issues raised by Elisabeth of Bohemia.
Recently, Gottlieb published an article in Lapham’s Quarterly looking into the relationship between Descartes and Princess Elizabeth of Bohemia. It’s a great article looking into the various arguments that the Princess and Descartes put forward for dualism. However, this article will look more in-depth into the philosophical grounds for both sides of the arguments and how we can use Hume’s philosophy to back up Descarte’s defence.
How did Descarte see the mind and the body?
Descartes believed that the mind and the body were split and made up of two substances (a substance is an entity which depends on nothing else for its existence except from God). This is known as substance dualism or Cartesian Dualism. He believed that the mind interacted with the body through the pineal gland with “animal spirit” taking the messages from the mind to and through the body.
Why did he argue for this?
Descarte uses two arguments to argue for substance dualism; the indivisibility argument and the conceivability argument
The indivisibility argument uses Leibniz’s Law to demonstrate that the mind and the body have different properties so are two different substances. Leibniz’s Law argues that when two entities have the same properties, they are the same thing. However, if they have different properties, they can’t be the same thing and must be different. Through introspection, Descartes realizes the mind is indivisible, as we cannot imagine our consciousness being split into two. It is a single entity that cannot be split. In contrast, the body is divisible. We can take a meat cleaver to it and chop it up into pieces. As a result of these two premises, the mind and the body have separate properties. Therefore, according to Leibniz’s Law, the mind and the body must be made of two separate entities (or substances) which argues for substance dualism.
The conceivability argument demonstrates substance dualism because it argues that, because we can conceive the essential natures of the body and the mind as separate. This is because, through introspection, it’s revealed that the true essence of the mind is an unextended (not within space), thinking thing. This contrasts to the body, which doesn’t think and is extended in the external world. We can “clearly and distinctly” conceive of these two essential natures as separate. Therefore, as a result of this, they must be two separate substances.
How did Princess Elizabeth of Bohemia criticize this?
There have been many issues raised with the arguments above. However, the article focuses on the issues raised by the Princess Elizabeth of Bohemia, who corresponded with Descartes through letters. She criticized his idea of substance dualism due to the impossibility of interaction. Substance dualism is a type of interactionist dualism; where the mind and the body has a two way causal interaction. For instance, when the mind wants a cup of tea, it causes the body to turn on the kettle. However, when you burn yourself on the kettle, pain appears in your mind. However, Princess Elizabeth rejected this two way causal interaction because of the lack of medium shared by the two substances. Whenever there is interaction between two things, there needs to be some common property or medium for this interaction to occur. However, the mind has no extended surface. As a result, there is no common medium between the two substances, and therefore substance dualism fails because it cannot account for how the two substances interact.
Another criticism raised was how the mind was attached to the body when it had no spatial property. As a result of having no spacial property, they cannot be linked to a specific location or body. Therefore, it makes no sense to claim that the mind is attached to the pineal gland. It also makes it difficult to see how our soul links to our body and not anyone else’s. Therefore, substance dualism fails because it cannot account for this interaction between the mind and the body without losing the ability to prove the mind and the body are two separate substances.
How does Descartes respond to this?
Descartes responds to this by arguing that we can’t base our idea of interactionism on what we understand by how physical objects interact. It is indeed the case that, when physical objects interact, they need a common medium to interact through (eg matter). However, this may not be the case for alternative causal interactions. Therefore, Descartes argues that we should respect the interactions of the mental and the physical as an interaction within itself and not base it on such a naive idea of causation.
To illustrate this, he uses the example of an object falling to Earth. There is no surface-to-surface contact, but gravity still interacts with the object causing it to fall to Earth. This demonstrates that it is not necessary to a common medium for two objects to interact. As a result, substance dualism doesn’t fail because it is possibly for the two substances to have two separate properties and still interact without having a common surface.
How do other philosophers respond to this?
Hume’s idea of causation can be used to back up Descartes’ defence. Hume believed that we cannot use a priori judgements for ideas of causation. For example, if we saw bread for the first time, we would not be able to work out through logic how that bread had come to be. We also would not be able to work out what cause it would have if we ate it. It is only through our experience that we know that bread is made from flour and yeast then baked and it is nutritious to us. Therefore, our idea of causation can only come from a posteriori knowledge and not a priori knowledge. Therefore, substance dualism doesn’t fail because the interaction of the mind and the body isn’t disproved as a result of our knowledge of physical interaction.