Marie asked:

My question is about Descartes’ dualism, Mind-Body Problem, I don’t quite understand it; I don’t get how he came to the conclusion that mind and body are two different substance. I’m hoping that you would be able to explain it to me please. Thank you!

Answer by Helier Robinson

My own opinion is that Descartes postulated two substances because he was both a devout catholic and a keen scientist, and the church was at loggerheads with science because of Copernicus’ heliocentric theory. According to Descartes the substance he called thought (mind) was the domain of the Church and the substance he called extension (matter) was the domain of science. And since these two substances could not interact there was no basic for a dispute between science and religion. Of course this left him with the problems of how mind could alter matter through muscular action and how mind could perceive matter.

Please note, however, that this psychological explanation is speculative: there is little scholarly evidence for it.