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Single Idea 14357

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

Full Idea

In the possible worlds account of conditionals A⊃B is not sufficient for A→B. If A is false then A⊃B is true, but here nothing is implied about whether the world most like the actual world except that A is true is or is not a B-world.

Clarification

⊃ is material implication, equivalent to ¬AvB

Gist of Idea

Possible worlds account, unlike A⊃B, says nothing about when A is false

Source

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

Book Ref

'Blackwell Guide to Philosophy of Language', ed/tr. Devitt,M/Hanley,R [Blackwell 2006], p.215

A Reaction

The possible worlds account seems to be built on Ramsey's idea of just holding A true and seeing what you get. Being committed to B being automatically true if A is false seems highly counterintuitive.

The 52 ideas from Frank Jackson

8499 Nominalists cannot translate 'red resembles pink more than blue' into particulars [Jackson]
8500 Colour resemblance isn't just resemblance between things; 'colour' must be mentioned [Jackson]
14288 'If A,B' affirms that A⊃B, and also that this wouldn't change if A were certain [Jackson, by Edgington]
13769 Conditionals are truth-functional, but should only be asserted when they are confident [Jackson, by Edgington]
14289 There are some assertable conditionals one would reject if one learned the antecedent [Jackson, by Edgington]
14353 Modus ponens requires that A→B is F when A is T and B is F [Jackson]
14354 When A and B have the same truth value, A→B is true, because A→A is a logical truth [Jackson]
14355 (A&B)→A is a logical truth, even if antecedent false and consequent true, so it is T if A is F and B is T [Jackson]
14352 '¬', '&', and 'v' are truth functions: the truth of the compound is fixed by the truth of the components [Jackson]
14358 In the possible worlds account of conditionals, modus ponens and modus tollens are validated [Jackson]
14360 Possible worlds for subjunctives (and dispositions), and no-truth for indicatives? [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]
14356 We can't insist that A is relevant to B, as conditionals can express lack of relevance [Jackson]
13858 The truth-functional account of conditionals is right, if the antecedent is really acceptable [Jackson, by Edgington]
7880 If a blind persons suddenly sees a kestrel, that doesn't make visual and theoretical kestrels different [Papineau on Jackson]
7378 No one bothers to imagine what it would really be like to have ALL the physical information [Dennett on Jackson]
7377 Mary learns when she sees colour, so her complete physical information had missed something [Jackson]
4894 I say Mary does not have new knowledge, but knows an old fact in a new way [Perry on Jackson]
4895 Is it unfair that physicalist knowledge can be written down, but dualist knowledge can't be [Perry on Jackson]
4886 Mary knows all the physical facts of seeing red, but experiencing it is new knowledge [Jackson]
6976 In physicalism, the psychological depends on the physical, not the other way around [Jackson]
6975 Possible worlds could be concrete, abstract, universals, sentences, or properties [Jackson]
7005 Something can only have a place in a preferred account of things if it is entailed by the account [Jackson]
6979 Serious metaphysics cares about entailment between sentences [Jackson]
6977 Egocentric or de se content seems to be irreducibly so [Jackson]
6980 Conceptual analysis studies whether one story is made true by another story [Jackson]
6982 Long arithmetic calculations show the a priori can be fallible [Jackson]
6991 We examine objects to determine colour; we do not introspect [Jackson]
6990 Keep distinct the essential properties of water, and application conditions for the word 'water' [Jackson]
6985 Analysis is finding necessary and sufficient conditions by studying possible cases [Jackson]
6989 I can understand "He has a beard", without identifying 'he', and hence the truth conditions [Jackson]
6983 Intuitions about possibilities are basic to conceptual analysis [Jackson]
6984 Smooth reductions preserve high-level laws in the lower level [Jackson]
6986 Is the dependence of the psychological on the physical a priori or a posteriori? [Jackson]
6987 We should not multiply senses of necessity beyond necessity [Jackson]
6988 Mathematical sentences are a problem in a possible-worlds framework [Jackson]
6993 Redness is a property, but only as a presentation to normal humans [Jackson]
6992 If different states can fulfil the same role, the converse must also be possible [Jackson]
6995 Successful predication supervenes on nature [Jackson]
6994 Truth supervenes on being [Jackson]
6996 Folk psychology covers input, internal role, and output [Jackson]
6998 Folk morality does not clearly distinguish between doing and allowing [Jackson]
6997 Moral functionalism says moral terms get their meaning from their role in folk morality [Jackson]
7000 Which are prior - thin concepts like right, good, ought; or thick concepts like kindness, equity etc.? [Jackson]
6999 It is hard to justify the huge difference in our judgements of abortion and infanticide [Jackson]
6978 Baldness is just hair distribution, but the former is indeterminate, unlike the latter [Jackson]
14707 Conceptual analysis is needed to establish that metaphysical reductions respect original meanings [Jackson, by Schroeter]
14632 Quine may have conflated de re and de dicto essentialism, but there is a real epistemological problem [Jackson]
14631 How can you show the necessity of an a posteriori necessity, if it might turn out to be false? [Jackson]
14633 How do we tell a table's being contingently plastic from its being essentially plastic? [Jackson]
14635 An x is essentially F if it is F in every possible world in which it appears [Jackson]