Rene Descartes' concept of Dualism, otherwise known as Cartesian Dualism, is considered one of his greatest contributions in the history of philosophy. He was the first to argue that the mind is a non-material entity which is distinct and separate from the brain. He also identified the mind with concepts such as self-awareness and self-consciousness. He emphasized the sharp division between the mind and the body as the most basic fact of our human existence. In his work, Meditations, Descartes began his philosophical journey by finding out the things which he can claim absolute certainty from those which he is doubtful. He started to clear his mind of all the rubbish knowledge that had been handed down from generations to generations. He was well aware that he may have harbored certain ideas which may have been shaped by biases and prejudices. He challenged himself to eliminate these prejudices so that he could arrive at the very foundations of knowledge. He also refused to accept the Aristotelian and Scholastic philosophy which had dominated the traditional philosophical thought throughout the Medieval Period 7. .
He (Descartes) thought that if true knowledge is to be attained then we must start from the very foundation of our knowledge. He thus began his philosophy by doubting everything that he could not be certain. Descartes doubted everything around him. He doubted the existence of the physical universe, the people around, his body and even his existence. He thought that it may be possible that he could be hallucinating about the existence of this physical world or his physical body. He even doubted his senses, to wit: "All that I have, up to this moment, accepted as possessed of the highest truth and certainty, I received either from or through the senses. I observed, however, that these sometimes misled us; and it is the part of prudence not to place absolute confidence in that by which we have even once been deceived.
