The human body is a material object that is part of the natural world. It is a uniquely personal part of the natural world, but it is a physical substance nonetheless. How it functions internally and how it responds to external phenomena are governed by the principles of living matter, which are the subject of biology. The parts of the body fit together in regular and predictable ways, for example, and fulfil specific functions. All bodies need water, energy and oxygen. They have a limited life-span and they are subject to various infirmities.
As part of the natural world, the human body can be studied using the methods and techniques of natural science. Despite our intimate connection with our bodies, it is possible for us to discover and formulate general properties about how the human body works.
Now, many people are uncomfortable with the idea that there is a difference between the characteristics of the natural world and the human world, or between our relationship to one and to the other. The proposal that there are differences in the way we understand the human body and human activity seems to make people particularly uneasy. It is often misunderstood as illustrating the ‘mind-body problem’, and held up as an example of the great crime of ‘dualism’.
Dualism is the name for the philosophical problem most often associated with the work of the 17th century French philosopher, René Descartes. Descartes was responding to the philosophical position known as scepticism; the claim that we cannot know anything. To find something he thought was absolutely certain and beyond doubt, Descartes turned to our inner experience (‘I think therefore I am’). But by establishing our inner experience as the benchmark of knowledge he thereby set up the problem of how we can have knowledge of anything else, including the external world and ‘other minds’.
Wittgenstein and Heidegger are both responding to the problems created by Descartes’ solution to scepticism. They both suggest that the problem is a false problem, created by the mistaken notion that knowledge is ‘inner’. For Wittgenstein and Heidegger, we are inherently connected with the world and with other minds or people. The individual ‘mind’ is not an isolated substance or entity. The nature of our mental life, that is how we make sense of the world, is derived from the social world in which we are embedded. Hegel pointed this out, in fact, long before Wittgenstein and Heidegger. Our basic understanding of the things around us, even being able to pick out things like trees and flowers, depends on the concepts we inherit from the society we are born into.
On this view, knowledge is a function of human beings living together within the world. Knowledge is inherently public. Our individual, private experience is just that- it is experience, it is not knowledge. A single isolated individual might impose some order on their experience, but a mind in isolation from the world and other humans could not produce anything that we would think of as knowledge.
Many people’s objection to Descartes arises from discomfort with the postulation of a non-material type substance such as mind. Such a suggestion seems to hark back to the religious idea of a soul and sits uncomfortably with our modern materialist age. Indeed, as Szasz suggests, Descartes work can be read as an attempt to ‘impart scientific credibility to the theological concept of the soul’ (1).
What Wittgenstein and Heidegger show is that there is no need to postulate any non-material entity like mind or soul. Our subjective, individual perspective on the world is not some mysterious force or being. It is just what it is to be an individual organism. It is part of the structure of the experience of living. That individual organisms have their own unique point of view is built into the grammar of our understanding, as reflected in our language with the use of personal pronouns and conjugation of verbs.
The problem of dualism is not resolved by saying that all things are the same. It is not addressed by the proposal that human ideas and activities are the same sort of thing as mountains and minerals. The problem of dualism starts off with a wrong-headed view of knowledge. If knowledge is understood as a product of an interaction between human society and its world, then the problem of dualism melts away.
This solution emphasises rather than dissolves the difference between the human world and the natural world, especially in terms of how we relate to, or ‘know,’ these different spheres. It emphasises that human beings are knowing subjects, and that we gain knowledge of other things through our interaction with them. It also stresses that our ability to know anything depends on our membership of a historical human community. Our relationship to other members of this community and to the community as a whole is therefore necessarily different from our relationship with the non-human things around us. As argued in the last blog, we cannot know ourselves as human beings in the way we know the material world.
Joanna Moncrieff 
It has been interesting to read. This subject of dualism surely has underlying significance to how we interact with others, and how we view ourselves.
I am interested to find out more on your conclusion: “If knowledge is understood as a product of an interaction between human society and its world, then the problem of dualism melts away.”
Please, by way of response to this comment or by way of another related post, do take the time to elaborate on your conclusion. Thank you.
Wishing you well in these writing endeavors.