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06-24-2002, 03:14 AM | #1 |
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Major Problems With Modal Logic
Some Problems With Modal Logic
I have discovered two major problems with modal logic, and no doubt there are more following similar forms. Anyone care to demolish my half-witted attempt at serious philosophy? Argument 1 - everything that is possible is actual 1. <>p (any logically possible thing) 2. <>p -> <>[]p (M10 Lewis axiom) 3. <>[]p (modus ponens from 1 and 2) 4. <>[]p -> p (derived from axiom B) 5. p (modus ponens from 3 and 4) Argument 2 - everything that is actual is necessary 1. p (any actual thing) 2. p -> <>p (H5 or M6 Lewis axiom) 3. <>p (modus ponens from 1 and 2) 4. <>p -> <>[]p (M10 Lewis axiom) 5. <>[]p (modus ponens from 3 and 4) 6. <>[]p -> (p -> []p) (HCR1 axiom) 7. p -> []p (modus ponens from 5 and 6) 8. []p (modus ponens from 1 and 7) |
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