▲ | griffzhowl 2 days ago | |||||||
> It goes what step further, there are statements that are true but can not be proved. No, this is the misconception. I know it's often stated this way, but it's wrong. Godel showed that given any formal system, you can construct a statement that the system can neither prove nor disprove. But Godel actually proves this statement in his proof, so it's certainly not unprovable in general. | ||||||||
▲ | EthanHeilman a day ago | parent [-] | |||||||
As far as I can tell this is not a misconception, I am just not communicating clearly enough. I figured I could make the point at a higher level. You can construct a statement in an axiomatic system complex enough to express arithmetic: 1. Which is true, 2. AND which can be proved to be true under the assumption the system is consistent, 3. and which can not be proven true within that axiomatic system because you can't prove consistency of the system itself within the axiomatic system itself. The crass positivist position would be that such undecidable statements are meaningless, i.e. neither true nor false. The incompleteness theorems provide a strong counter-example: a statement which can not be proved within that axiomatic system, but is true (if the system is consistent). The positivists must then amend their position to include things which can't be proved within the axiomatic system but can be proved true. This resulted in the watered down late-positivism. | ||||||||
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