Descartes External World Skepticism

External world skepticism is the view that we can’t know anything about the external world, only the thoughts inside our mind. It calls into question the validity of our senses in order to have knowledge. It doubts that we really know anything is real in the outside world since our sense could be wrong and each individual perceives things differently. It says that our sense and perceptions are uncertain because there is no evidence to support what we see outside of our mind. This differs from the common-sense account that “seeing is believing” and that if we see something it must be true, because we can rely on our senses to give us evidence of the external world. It also differs because we can say we know something and have a justifiable

His arguments includes the following premises: P1: For all we can tell, we are being deceived by an evil demon. P2: If P1 is true, then we cannot be certain that we are not being so deceived. P3. If P2 is true, then we cannot know that we are not being so deceived. P4. If P3 is true, then we cannot know that there is an external world. C. Thus, we cannot know that there is an external world. He argues that with anything happening in our mind to askew our sense, we cannot rely on them to have proof of the external world, like he mentions because an evil demon could be conceiving us. Descartes conclusion from his premises give evidence to the fact that we can’t know anything about the external world, and that all we know is what is inside our minds. “I think therefore I am”. Descartes argument that we can’t know there is external world is captured by this quote because we should understand him as meaning his thoughts give him evidence of his existence but nothing else. If you only know that you exist because you are thinking, then anything else you think is unknown which therefore supports the argument that we cannot know there is an external world. He also ponders how to figure out when our sense are not deceiving us at any time, which is why we cannot trust our sense to provide us evidence of the external

He says heres’s a hand, theres’s another, they are external things (to my mind), there are at least two of them, therefore the external world exists. His proof is by wiggling his hands in front of his face and asking if we see them wiggle. Since the answer is yes that is proof of the external world. To prove the past external world he wiggles his hands above a desk. Five minutes later, he acknowledges he wiggles his hands over the desk, which is proof of the past external world. His justification for his proof are that the premise and conclusion must be different, the premises must be true and the conclusion must follow from the premises. With his definition of what a good proof is and an example that satisfies the three conditions for a good proof, he shows his evidence of the external world. To address Descartes point about how does one know if they are not dreaming, Moore states that he has conclusive evidence that he is awake, but that is different than being able to prove it, and since he cannot provide all of his conclusive evidence he cannot provide a proof. His conclusion through his proof that he he has two hands and that they exist externally of his mind, proves that we can know something in the external