Descartes’ Substance Dualism

Rene Descartes

Perhaps, the most iconic [aɪˈkɒnɪk] philosopher of mind is the 17th century philosopher. Now, Descartes was very famous for putting forward a particular view of how the mind worked

Substance [ˈsʌbstəns] dualism [ˈdju(ː)əlɪzm] (Cartesian [kɑːˈtiːzjən] Dualism)

Descartes thought that there were two types of substance in the world. There's physical stuff, stuff that our bodies are made of, stuff that trees are made of, metals [ˈmɛtlz], things in the world. But then, there was other fundamentally different substance which was immaterial [ˌɪməˈtɪərɪəl]. It couldn't be tracked by our best scientific instruments [ˈɪnstrʊmənts]. It was an immaterial substance and that was what our minds were. So, Descartes thought that for every human being, there were two bits of stuff. Each human being has a physical form, which is your kind of average [ˈævərɪʤ] compounds [ˈkɒmpaʊndz] of water, other chemicals [ˈkɛmɪkəlz], hormones [ˈhɔːməʊnz] that make up the human body. And in addition to this, there was this immaterial stuff, and that was the mind.

The problem with Descartes' view

Princess [prɪnˈsɛs] Elisabeth [ɪˈlɪzəbəθ] of Bohemia [bəʊˈhiːmjə], one of Descartes’ pupils, wrote to Descartes, asking, if we had this immaterial substance, then how it affected [əˈfɛktɪd] changes in the physical [ˈfɪzɪkəl] body.

‘She says, look, in order to, for physical things to move, they have to be moved by another physical thing. So, for a rock to roll down the hill, someone has to push it. It needs some impetus [ˈɪmpɪtəs] (толчок, импульс) from another physical object to start its journey down the hill. And she says, look, human beings, they're exactly the same. In order for them to move, in order for them to affect changes in the world, there has to be some kind of physical impetus that changes the physical state of us, of our body, such that we can move. She also says, look, if the substance of thoughts isn't physical, but how can we then interact [ˌɪntərˈækt] with the physical body so as to affect changes in the world? Because it's a fundamental feature of thoughts that the can cause our bodies to move’.

Princess Elizabeth of Bohemia wanted to know how an immaterial substance, which was so fundamentally different from the physical stuff, could cause a physical thing to move. This is known as the problem of causation [kɔːˈzeɪʃən], and it's a very tricky (коварный) one for Descartes and for substance dualism