display all the ideas for this combination of texts
3 ideas
| 4195 | It is impossible to reach a valid false conclusion from true premises, so reason itself depends on possibility [Lowe] |
| Full Idea: Reasoning itself depends upon a grasp of possibilities, because a valid argument is one in which it is not possible for the conclusion to be false if the premises are true. | |
| From: E.J. Lowe (A Survey of Metaphysics [2002], p.11) | |
| A reaction: A very valuable corrective to my pessimistic view of philosophers' attempts to understand metaphysical necessity. But if we can only grasp natural necessity, then all reason is naturalistic. |
| 14283 | A conditional probability does not measure the probability of the truth of any proposition [Lewis, by Edgington] |
| Full Idea: Lewis was first to prove this remarkable result: there is no proposition A*B such that, in all probability distributions, p(A*B) = pA(B) [second A a subscript]. A conditional probability does not measure the probability of the truth of any proposition. | |
| From: report of David Lewis (Probabilities of Conditionals [1976]) by Dorothy Edgington - Conditionals (Stanf) 3.1 | |
| A reaction: The equation says the probability of the combination of A and B is not always the same as the probability of B given A. Bennett refers to this as 'The Equation' in the theory of conditionals. Edgington says a conditional is a supposition and a judgement. |
| 4207 | We might eliminate 'possible' and 'necessary' in favour of quantification over possible worlds [Lowe] |
| Full Idea: It may be possible to eliminate the modal operators (in English, 'is possible' and 'is necessary') in favour of quantifier expressions with variables ranging over possible worlds. | |
| From: E.J. Lowe (A Survey of Metaphysics [2002], p.121) | |
| A reaction: Hence 'necessary' becomes 'exists/is true in all possible worlds'. Deep problems, but at least we must show that referring to 'possible' worlds isn't a circular explanation of 'is possible'. |