more from this thinker     |     more from this text

Single Idea 14358

[filed under theme 10. Modality / B. Possibility / 8. Conditionals / d. Non-truthfunction conditionals ]

Full Idea

In the possible worlds account modus ponens is validated (the closest world, the actual, is a B-world just if B is true), and modus tollens is validated (if B is false, the actual world is not an A-world, so A is false).

Gist of Idea

In the possible worlds account of conditionals, modus ponens and modus tollens are validated

Source

Frank Jackson (Conditionals [2006], 'Famous')

Book Ref

'Blackwell Guide to Philosophy of Language', ed/tr. Devitt,M/Hanley,R [Blackwell 2006], p.216

A Reaction

[see Jackson for slightly fuller versions] This looks like a minimal requirement for a decent theory of conditionals, so Jackson explains the attractions of the possible worlds view very persuasively.

The 15 ideas with the same theme [conditional truth adding to the components]:

14304 Conditionals are true when the antecedent is true, and the consequent has to be true [Diod.Cronus]
14303 Truth-functional conditionals have a simple falsification, when A is true and B is false [Peirce]
10993 Ramsey's Test: believe the consequent if you believe the antecedent [Ramsey, by Read]
13766 'If' is the same as 'given that', so the degrees of belief should conform to probability theory [Ramsey, by Ramsey]
14358 In the possible worlds account of conditionals, modus ponens and modus tollens are validated [Jackson]
14359 Only assertions have truth-values, and conditionals are not proper assertions [Jackson]
14357 Possible worlds account, unlike A⊃B, says nothing about when A is false [Jackson]
10994 Conditionals are true if minimal revision of the antecedent verifies the consequent [Stalnaker, by Read]
14271 Non-truth-functionalist say 'If A,B' is false if A is T and B is F, but deny that is always true for TT,FT and FF [Edgington]
14272 I say "If you touch that wire you'll get a shock"; you don't touch it. How can that make the conditional true? [Edgington]
13855 A conditional does not have truth conditions [Edgington]
13859 X believes 'if A, B' to the extent that A & B is more likely than A & ¬B [Edgington]
14311 Dispositions are not equivalent to stronger-than-material conditionals [Mumford]
14185 Conditionals are just a shorthand for some proof, leaving out the details [Read]
8949 In relevance logic, conditionals help information to flow from antecedent to consequent [Fisher]