Moore’s Proof of an External World
- Here is one hand.
- Here is another hand.
- Hands are objects external to our minds.
- ∴ At least two external objects exist. from 1, 2, 3
- ∴ The external world exists. from 4
Moore held the premises are more certain than any skeptical principle that could be used against them. The standard complaint is that the proof is question-begging or fails to transmit warrant (Wright 2002); Moore's reply is that a proof need not convince the skeptic to be a proof.
G. E. Moore, “Proof of an External World”, Proceedings of the British Academy 25: 273–300, 1939.
The Explanationist Argument for the External World
- Our sensory experiences are richly detailed, coherent, and lawfully ordered.
- The real-world hypothesis explains the order and coherence of our experience better than any skeptical rival (dreams, demons, simulations).
- We are justified in believing the hypothesis that best explains our evidence.
- ∴ The external world exists. from 1, 2, 3
Descends from Russell's 'instinctive belief' response in The Problems of Philosophy (1912). Vogel argues the real-world hypothesis beats skeptical rivals on explanatory virtues like simplicity, since skeptical hypotheses must smuggle in an isomorphic copy of the world to explain the same data.
Jonathan Vogel, “Cartesian Skepticism and Inference to the Best Explanation”, Journal of Philosophy 87 (11): 658–666, 1990.