Field II 252/296
Material Conditional/Adams Conditional/Field: (Lit. Adams 1974): (outside of mathematics): few of us would agree with the following conclusion: E.g. from
Clinton will not die in office
to
If Clinton dies in office, Danny de Vito will become President.
That suggests that here the equivalence between A > B and ~(A v B) does not exist.
>
Counterfactuals, >
Counterfactual conditional.
In other words: If A then B does not seem to have the same truth conditions as ~A v B.
>
Truth conditions.
Adams-conditional: it may only be used as a main operator. - The degree of belief of A > B is always the conditional belef degree (B I A).
>
Operators, >
Conditional probability.
II 253
In the case of the indicative conditional, the premise is always required. - Adams: intuitively, conclusions with conditionals are correct. Problem: then they will say less about the world.
Indicative conditional sentence/material implication/truth/field: further considerations have however led many to doubt that there are truth conditions here at all.
>
Material implication.
Conditional/Field: A > B: here the premise A is always required when concluding. That is, we accept conditional B relative to premise A.
Adams: the idea of contingent acceptance justifies our intuitive beliefs according to which conclusions with conditionals are correct.
Cf. >
Presuppositions, >
Principle of Charity.
But then it is anything but obvious that conditionals say something about the world. For example, there must not be a statement C whose probability in all circumstances is the same as the conditional (contingent) probability of (B I A). That is, the conditional A > B is not such a C.
N.B.: this shows that we do not have to assume "conditional propositions" or "conditional facts". This is the nonfactualist view.
>
Nonfactualism.
((s) Truth conditions/nonfactualism/conditional/(s): if there are no facts, then there are also no truth conditions.)
Borderline case: If the conditional (contingent) probability is 0 or 1, it is justifiable that the assertibility conditions (acceptance conditions) are the same as those of the material conditional.
Vs: one could argue that a sentence without any truth conditions is meaningless.
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Assertibility, >
Assertibility conditions.
Field: ditto, but the main thing is that one cannot explain the acceptance conditions without the truth conditions in terms of the truth conditions.
>
Truth conditions.
1. R. Adams (1974). Theories of Actuality. Nous, 5: 21-231.
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Lewis V 133
Conditional/Adams/Adams-conditional/Lewis: is an exception to the rule that the speaker usually expresses nothing that is probably untrue. - Then the assertibility goes rather with the conditional subjective probability of the consequent.
>
Subjective probability, >
Conditional probability, >
Probability.