One of Descartes main points is that the one thing you can know for sure is radical doubt, to doubt everything. The only thing you can’t doubt is that he is. One of the most famous lines from Descartes is “I think therefore I am” which is a main point in the separation of the humans and “Guests” being created by Solaris. The Guests on board ship cannot recollect for themselves, they need to be taught about their pasts in order to learn. The Guests are dependent on the humans around them. They are just bodies at this point, their minds underdeveloped and only knowing how to function mechanically as a human. They do not doubt because they do not know they are. In one scene from the movie, Hari who is a clone of Kris Kyle’s deceased wife, admits to not knowing herself and not being able to recollect her face or Kyle’s face. They cannot think and deduct and reason for themselves because they have no prior knowledge to base anything off of. Hari is constantly evolving as a Guest because she is around Kyle more and more. The more she experiences with him, the more she can formulate hypothesis. The Guests can only doubt externally, they ask questions. Hari’s first doubt is of Kyle’s love for her but this is only because he has yet to show affection towards her. She asks Kyle point blank, “do you love me?” This kind of doubting is that of learning, Hari will not reach a point in the movie to question her existence because she cannot doubt against it. She does not know how she got to Solaris, where she came from or what she came from.
Descartes also speaks about dualism, which is supported in Solaris. Descartes theory of dualism suggests that the body acts like a machine and has material properties.The mind is the opposite and is in connection with the soul which is non-material. They come together at the pineal gland, which suggests that the non-material mind controls the material body. This theory supports Hari because when she breaks down the solid metal door using her body, her naive and uneducated mind allowed her to do that.