Descartes thinks that body and mind are separate entities: Why is this still important?

Descartes thinks that body and mind are separate entities: Why is this still important?


Descartes is considered by many as the most influential thinker of the early modern era. He came up with the aspect of accepting as true only what is indubitable in order to analyse the external world and ‘the existence of God‘, famously exemplified in his Meditations on First Philosophy. He claimed that the natures of body and mind are separate and distinct entities capable of existing separately (Duncan, 2008). The body is regarded as a physical entity composed of matter that does not occupy space and whose essence is extension. On the other hand, the mind is understood to be a non-material entity which is indivisible and whose essence is thinking. He called the mind a ‘thinking thing’ to which his popular phrase ‘I think, therefore I am’ (Cogito), is closely related (Hatfield 2003). As metaphors help us to reduce the complexity and expand our understanding of the things that we want to describe, this short blog post will highlight the unchanged importance of Descartes‘ dualism of living body and mind in three images.

  1. Plato’s Allegory of the cave: Following the deconstruction of Peter Millican (2010), which Descartes considers in his Meditations ‘I think, therefore I am’ as a general rule of thinking, he based his argument on his own mental faculties. He attempts to defeat or circumvent sceptism: ‘which is to withhold assent from anything that is not completely certain‘ (ibid.). For Descartes, certainty could only evolve, if he ‘clearly and distinctively perceived’ it to be true. For example, sensations help us to understand different qualities of the external world such as colour, taste, smell, and sound. But these qualities do not belong to physical substances; they only exist in our own mind. Through this, Descartes claims to prove the existence of God, but his thinking seems to be circular. He tries to prove the existence of God by relying on his mental faculties and then appeals to the existence of God to justify the reliability of mind (Hatfield 2003). Descartes’ metaphysical position has not withstood the test of time. Since our faculties may be misleading or deceptive, it may be difficult to prove the existence of God. However, this may comply with any other argument that sceptism should be defeated. Although the underlying premise is not plausible, Cartesian dualism is still an important doctrine that continues to receive much attention to the present day. 
  2. Dream of thinking machines: Descartes’ differentiation between body and mind is based on substance (substance dualism) which can be contrasted with property dualism – the distinction between physical and non-physical properties. According to Millican (2010), Descartes based his claims in his Meditation VI on three presumptions: (i) a clear understanding of himself as ‘thinking, non-extended entity’, (ii) a clear understanding of the body as an extended and non-thinking thing, and (iii) anything he clearly and distinctly understands could be created by God. He then concluded that his mind is separate and distinct from his body. It is, however, not clear how both entities with distinct substances could interact, as Descartes leaves no room of how the mind would be capable of influencing the body. What is clear is that the metaphysical world influences the physical world and vice-versa. Different philosophical views developed over time such as (a) interactionism: the mind or body can mutually influence each other such as through movement or pain; (b) epiphenomenalism: the mind is regarded as an ‘epiphenomenon’ caused by events in the brain; and (c) physicalism: only physical things exist, so there is no mind beyond the physical brain (Stewart, Blocker, & Petrik 2013, 175). However, one position has been validated by subsequent scientific discoveries, the distinction between primary and secondary qualities. Research in chemistry, physics, and neuroscience has shown that we actually live in a colourless, painless, tasteless, and odourless world. Secondary qualities come only into existence because of sensations, thoughts, and ideas connected to our mind. 
  3. Self as a mirror: It is clear how all these different versions of mind and body differences are related to consciousness and different mental experiences. Conscious experiences cannot be justified by substance dualism. Based on the argument of the famous neuropsychologist Antonio Damasio (2011), consciousness is an important function of mind to develop a self. He defines consciousness as a mind with movements of mental images. Without consciousness, we would not be able to generate and process knowledge and information (Stewart, Blocker & Petrik, 2013). According to Damasio (2011), we have a self that is represented in neural maps. The self not only makes possible the continuity of one’s own self from day to day, but also establishes a permanent bound between brain and body. In neuroscience, the brain stem is understood to be responsible for the consciousness and socio-cultural regulations.

In conclusion, it is clear that Descartes not only took a critical stance on sceptism, but also analysed and enriched human thinking of its critical distinction between body and mind. His Meditations have become fundamental to subsequent scientific discoveries. At the same time neurosciences spearhead current research to develop theories and test brain functions to challenge Cartesian dualism. Even though many would be motivated by his desire to get and know the truth, some people would say that not all the topics should be subjected to argument. Descartes argument relies purely on a priori reasoning. He accepts that the belief in God is merely based on faith and he shows that at it is least reasoning to believe in God. At the same time, Descartes argument on the existence of self has a syllogistic inference on “I am thinking” to “I exist.” It appeared to need more premise even though he denied that Cogito is a syllogism. Additionally, it is noted that priori propositions or self-evident ideas give no information of the actual world.


Damasio, A. (2011). The Quest to Understanding Consciousness. [Video TedTalk]. URL [18/04/2018].

Descartes, R. and Cress, D. (1993). Meditations on First Philosophy. Indianapolis: Hackett Pub. Co.

Duncan, S.M. (2008). The Proof of the External World: Cartesian Theism and the Possibility of Knowledge. Cambridge: James Clarke & Co.

Hatfield, G. (2003). Routledge Philosophy Guidebook to Descartes and the Meditations, London: Routledge.

Millican, P. (2010). General Philosophy. [Audio Podcast]. Oxford. URL [18/04/2018].

Stewart, D., Blocker, H., & Petrik, J. (2012). Fundamentals of Philosophy. 8th ed. Boston: Pearson.

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Dr. Maik Arnold is Professor for Non-Profit-Management and Vice-President for Research, Innovation and Transfer at University of Applied Science Dresden.