how did descartes define the human being?
Certainly Descartes conceived of man as a rational being, as his famous dictum "Cogito, ergo sum," articulated in Meditations on First Philosophy (1641) indicates. However, it is important to remember that this statement came in the context of a philosophical exercise wherein Descartes was trying to discover a first principle that one could be certain was true. The fact the men existed was this principle. But Descartes went much further than this, arguing that human psychology worked in ways analogous to a machine (which was indeed how the Cartesian world worked.) He claimed that humans were capable of comprehending everything in the universe through the use of rational thought and mathematics.
Descartes also conceived of human beings in terms that have been described as "dualistic." This way of thinking, which has become known as "Cartesian dualism," differentiated between mind and body, arguing that the two were distinct. Man had a mind, which was not physical, and a body, which occupied a physical space. The mind influenced the body by directing it, and the body influenced the mind through providing external stimuli. On the other hand, he also argued that the mind was the only aspect of human existence that could not be doubted (hence "cogito ergo sum") and thus claimed that it was the essence of humanity.
Descartes summed up human existence in one very simple phrase:
"I think, therefore I am."
One thing I know about Descartes is that he believed there was dualism in people. There was the 'Res cogitans' about the mind / spirit which wasn't spatial but free and there was the Res extensa about the body which had expanse, figural quantity, mechanism and was specified.
I hope this will help you.. I looked it up in a Dutch philosophie book and tried to translate it for you (pretty difficult if the book itself should already be read with a Dutch dictionary aside to understand the texts..)