External World Skepticism
(The view, which involves the idea that we have no good reason to believe that our perceptions of the world are veridical, is called external world skepticism. )
External World Skepticism is the thesis that we cannot know what the world outside of our minds is like.
Here are two hypotheses:
Hypothesis1: the external world causes us to have veridical experience. For example, a tree causes me to have an experience of a tree when I look at it. These experiences are veridical. (This hypothesis assumes that common sense realism is true).
Hypothesis2: I am a brain in a vat, and an evil scientist causes be to have non-veridical experiences. For example, he can cause me to have an experience of a tree that is qualitatively identical to the experience of a tree explained in thesis 1. These experiences are non-veridical. (This hypothesis assumes that common sense realism is false).
Here is a precise statement of argument for external world skepticism: 1) If we have two hypotheses that postulate qualitatively identical experiences, then we can’t know on the basis of experience which of the two hypotheses is correct. 2) Hypotheses 1 and 2 postulate qualitatively identical experiences, so we can’t know on the basis of experience which of hypotheses 1 and 2 is correct. --from(1) 3) We can’t know independently of experience which of hypotheses 1 and 2 is correct 4) Therefore, we can’t know which hypothesis is correct, period. from(2)and (3) 5) But knowledge of the external world(the denial of external world skepticism)entails that we know that hypothesis 2 is incorrect, and common sense realism implies that we know that hypothesis 1 is correct. 6) Since we can’t know this, we can’t have knowledge of the external world. This is External World Skepticism.
Premise(1) is very plausible. How can experience alone select between hypotheses that predict the very same experience? (2) follows from (1) together with our hypotheses. Premise(3) seems
External World Skepticism is the thesis that we cannot know what the world outside of our minds is like.
Here are two hypotheses:
Hypothesis1: the external world causes us to have veridical experience. For example, a tree causes me to have an experience of a tree when I look at it. These experiences are veridical. (This hypothesis assumes that common sense realism is true).
Hypothesis2: I am a brain in a vat, and an evil scientist causes be to have non-veridical experiences. For example, he can cause me to have an experience of a tree that is qualitatively identical to the experience of a tree explained in thesis 1. These experiences are non-veridical. (This hypothesis assumes that common sense realism is false).
Here is a precise statement of argument for external world skepticism: 1) If we have two hypotheses that postulate qualitatively identical experiences, then we can’t know on the basis of experience which of the two hypotheses is correct. 2) Hypotheses 1 and 2 postulate qualitatively identical experiences, so we can’t know on the basis of experience which of hypotheses 1 and 2 is correct. --from(1) 3) We can’t know independently of experience which of hypotheses 1 and 2 is correct 4) Therefore, we can’t know which hypothesis is correct, period. from(2)and (3) 5) But knowledge of the external world(the denial of external world skepticism)entails that we know that hypothesis 2 is incorrect, and common sense realism implies that we know that hypothesis 1 is correct. 6) Since we can’t know this, we can’t have knowledge of the external world. This is External World Skepticism.
Premise(1) is very plausible. How can experience alone select between hypotheses that predict the very same experience? (2) follows from (1) together with our hypotheses. Premise(3) seems