Ideas of Dorothy Edgington, by Theme

[British, fl. 1997, Professor at Oxford University, and at Birkbeck, London.]

green numbers give full details    |    back to list of philosophers    |     unexpand these ideas    |    
4. Formal Logic / B. Propositional Logic PL / 2. Tools of Propositional Logic / c. Derivation rules of PL
Conditional Proof is only valid if we accept the truth-functional reading of 'if'
     Full Idea: Conditional Proof seems sound: 'From X and Y, it follows that Z. So from X it follows that if Y,Z'. Yet for no reading of 'if' which is stronger that the truth-functional reading is CP valid, at least if we accept (A&B);A; therefore B.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 2.2)
     A reaction: See the section of ideas on Conditionals (filed under 'Modality') for a fuller picture of this issue. Edgington offers it as one of the main arguments in favour of the truth-functional reading of 'if' (though she rejects that reading).
10. Modality / A. Necessity / 1. Types of Modality
There are two families of modal notions, metaphysical and epistemic, of equal strength
     Full Idea: In my view, there are two independent families of modal notions, metaphysical and epistemic, neither stronger than the other.
     From: Dorothy Edgington (Two Kinds of Possibility [2004], Abs)
     A reaction: My immediate reaction is that epistemic necessity is not necessity at all. 'For all I know' 2 plus 2 might really be 95, and squares may also be circular.
10. Modality / A. Necessity / 5. Metaphysical Necessity
Metaphysical possibility is discovered empirically, and is contrained by nature
     Full Idea: Metaphysical necessity derives from distinguishing things which can happen and things which can't, in virtue of their nature, which we discover empirically: the metaphysically possible, I claim, is constrained by the laws of nature.
     From: Dorothy Edgington (Two Kinds of Possibility [2004], I)
     A reaction: She claims that Kripke is sympathetic to this. Personally I like the idea that natural necessity is metaphysically necessary (see 'Scientific Essentialism'), but the other way round comes as a bit of a surprise. I will think about it.
10. Modality / A. Necessity / 6. Logical Necessity
Logical necessity is epistemic necessity, which is the old notion of a priori
     Full Idea: Edgington's position is that logical necessity is an epistemic notion: epistemic necessity which, she claims, is the old notion of the a priori. Like Kripke, she thinks this is two-way independent of metaphysical necessity.
     From: report of Dorothy Edgington (Epistemic and Metaphysical Possibility [1985]) by Ian McFetridge - Logical Necessity: Some Issues 1
     A reaction: [her paper was unpublished] She hence thinks an argument can be logically valid, while metaphysically its conclusion may not follow. Dubious, though I think I favour the view that logical necessity is underwritten by metaphysical necessity.
An argument is only valid if it is epistemically (a priori) necessary
     Full Idea: Validity is governed by epistemic necessity, i.e. an argument is valid if and only if there is an a priori route from premises to conclusion.
     From: Dorothy Edgington (Two Kinds of Possibility [2004], V)
     A reaction: Controversial, and criticised by McFetridge and Rumfitt. I don't think I agree with her. I don't see validity as depending on dim little human beings.
Broadly logical necessity (i.e. not necessarily formal logical necessity) is an epistemic notion
     Full Idea: So-called broadly logical necessity (by which I mean, not necessarily formal logical necessity) is an epistemic notion.
     From: Dorothy Edgington (Two Kinds of Possibility [2004], I)
     A reaction: This is controversial, and is criticised by McFetridge and Rumfitt. Fine argues that 'narrow' (formal) logical necessity is metaphysical. Between them they have got rid of logical necessity completely.
10. Modality / B. Possibility / 6. Probability
Truth-functional possibilities include the irrelevant, which is a mistake
     Full Idea: How likely is a fair die landing on an even number to land six? My approach is, assume an even number, so three possibilities, one a six, so 'one third'; the truth-functional approach is it's true if it is not-even or six, so 'two-thirds'.
     From: Dorothy Edgington (Do Conditionals Have Truth Conditions? [1986], 3)
     A reaction: The point is that in the truth-functional approach, if the die lands not-even, then the conditional comes out as true, when she says it should be irrelevant. She seems to be right about this.
A thing works like formal probability if all the options sum to 100%
     Full Idea: One's degrees of belief in the members of an idealised partition should sum to 100%. That is all there is to the claim that degrees of belief should have the structure of probabilities.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 3.1)
Conclusion improbability can't exceed summed premise improbability in valid arguments
     Full Idea: If (and only if) an argument is valid, then in no probability distribution does the improbability of its conclusion exceed the sum of the improbabilities of its premises. We can call this the Probability Preservation Principle.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 3.2)
     A reaction: [Ernest Adams is credited with this] This means that classical logic is in some way probability-preserving as well as truth-preserving.
10. Modality / B. Possibility / 8. Conditionals / a. Conditionals
It is a mistake to think that conditionals are statements about how the world is
     Full Idea: The mistake philosophers have made, in trying to understand the conditional, is to assume that its function is to make a statement about how the world is (or how other possible worlds are related to it), true or false, as the case may be.
     From: Dorothy Edgington (Do Conditionals Have Truth Conditions? [1986], 1)
     A reaction: 'If pigs could fly we would never catch them' may not be about the world, but 'if you press this switch the light comes on' seems to be. Actually even the first one is about the world. I've an inkling that Edgington is wrong about this. Powers!
Validity can preserve certainty in mathematics, but conditionals about contingents are another matter
     Full Idea: If your interest in logic is confined to applications to mathematics or other a priori matters, it is fine for validity to preserve certainty, ..but if you use conditionals when arguing about contingent matters, then great caution will be required.
     From: Dorothy Edgington (Conditionals [2001], 17.2.1)
10. Modality / B. Possibility / 8. Conditionals / b. Types of conditional
There are many different conditional mental states, and different conditional speech acts
     Full Idea: As well as conditional beliefs, there are conditional desires, hopes, fears etc. As well as conditional statements, there are conditional commands, questions, offers, promises, bets etc.
     From: Dorothy Edgington (Conditionals [2001], 17.3.4)
Maybe forward-looking indicatives are best classed with the subjunctives
     Full Idea: According to some theorists, the forward-looking 'indicatives' (those with a 'will' in the main clause) belong with the 'subjunctives' (those with a 'would' in the main clause), and not with the other 'indicatives'.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 1)
     A reaction: [She cites Gibbard, Dudman and 1988 Bennett; Jackson defends the indicative/subjunctive division, and recent Bennett defends it too] It is plausible to say that 'If you will do x' is counterfactual, since it hasn't actually happened.
Simple indicatives about past, present or future do seem to form a single semantic kind
     Full Idea: Straightforward statements about the past, present or future, to which a conditional clause is attached - the traditional class of indicative conditionals - do (in my view) constitute a single semantic kind.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 1)
     A reaction: This contrasts with Idea 14269, where the future indicatives are group instead with the counterfactuals.
10. Modality / B. Possibility / 8. Conditionals / c. Truth-function conditionals
Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'?
     Full Idea: Are conditionals truth-functional - do the truth values of A and B determine the truth value of 'If A, B'? Are they non-truth-functional, like 'because' or 'before'? Do the values of A and B, in some cases, leave open the value of 'If A,B'?
     From: Dorothy Edgington (Conditionals [2001], 17.1)
     A reaction: I would say they are not truth-functional, because the 'if' asserts some further dependency relation that goes beyond the truth or falsity of A and B. Logical ifs, causal ifs, psychological ifs... The material conditional ⊃ is truth-functional.
'If A,B' must entail (A & B); otherwise we could have A true, B false, and If A,B true, invalidating modus ponens
     Full Idea: If it were possible to have A true, B false, and If A,B true, it would be unsafe to infer B from A and If A,B: modus ponens would thus be invalid. Hence 'If A,B' must entail (A & B).
     From: Dorothy Edgington (Conditionals [2001], 17.1)
     A reaction: This is a firm defence of part of the truth-functional view of conditionals, and seems unassailable. The other parts of the truth table are open to question, though, if A is false, or they are both true.
Inferring conditionals from disjunctions or negated conjunctions gives support to truth-functionalism
     Full Idea: If either A or B is true, then you are intuitively justified in believe that If A, B. If you know that (A&B), then you may justifiably infer that if A, B. The truth-functionalist gets both of these cases (disjunction and negated conjunction) correct.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 2.1)
     A reaction: [compressed version] This summarises two of Edgington's three main arguments in favour of the truth-functional account of conditions (along with the existence of Conditional Proof). It is elementary classical logic which supports truth-functionalism.
Truth-function problems don't show up in mathematics
     Full Idea: The main defects of the truth-functional account of conditionals don't show up in mathematics.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 2.3)
     A reaction: These problems are the paradoxes associated with the material conditional ⊃. Too often mathematical logic has been the tail that wagged the dog in modern philosophy.
The truth-functional view makes conditionals with unlikely antecedents likely to be true
     Full Idea: The truth-functional view of conditionals has the unhappy consequence that all conditionals with unlikely antecedents are likely to be true. To think it likely that A is to think it likely that a sufficient condition for the truth of A⊃B obtains.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 2.3)
     A reaction: This is Edgington's main reason for rejecting the truth-functional account of conditionals. She says it removes our power to discriminate between believable and unbelievable conditionals, which is basic to practical reasoning.
Doctor:'If patient still alive, change dressing'; Nurse:'Either dead patient, or change dressing'; kills patient!
     Full Idea: The doctor says "If the patient is still alive in the morning, change the dressing". As a truth-functional command this says "Make it that either the patient is dead in the morning, or change the dressing", so the nurse kills the patient.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 5)
     A reaction: Isn't philosophy wonderful?
10. Modality / B. Possibility / 8. Conditionals / d. Non-truthfunction conditionals
X believes 'if A, B' to the extent that A & B is more likely than A & B
     Full Idea: X believes that if A, B, to the extent that he judges that A & B is nearly as likely as A, or (roughly equivalently) to the extent that he judges A & B to be more likely than A & B.
     From: Dorothy Edgington (Do Conditionals Have Truth Conditions? [1986], 5)
     A reaction: This is a formal statement of her theory of conditionals.
A conditional does not have truth conditions
     Full Idea: A conditional does not have truth conditions.
     From: Dorothy Edgington (Do Conditionals Have Truth Conditions? [1986], 1)
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
     Full Idea: Non-truth-functional accounts agree that 'If A,B' is false when A is true and B is false; and that it is sometimes true for the other three combinations of truth-values; but they deny that the conditional is always true in each of these three cases.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 2.1)
     A reaction: Truth-functional connectives like 'and' and 'or' don't add any truth-conditions to the values of the propositions, but 'If...then' seems to assert a relationship that goes beyond its component propositions, so non-truth-functionalists are right.
I say "If you touch that wire you'll get a shock"; you don't touch it. How can that make the conditional true?
     Full Idea: Non-truth-functionalists agree that when A is false, 'If A,B' may be either true or false. I say "If you touch that wire, you will get an electric shock". You don't touch it. Was my remark true or false? They say it depends on the wire etc.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 2.1)
     A reaction: This example seems to me to be a pretty conclusive refutation of the truth-functional view. How can the conditional be implied simply by my failure to touch the wire (which is what benighted truth-functionalists seem to believe)?
10. Modality / B. Possibility / 8. Conditionals / e. Supposition conditionals
Conditionals express what would be the outcome, given some supposition
     Full Idea: It is often necessary to suppose (or assume) that some epistemic possibility is true, and to consider what else would be the case, or would be likely to be the case, given this supposition. The conditional expresses the outcome of such thought processes.
     From: Dorothy Edgington (Do Conditionals Have Truth Conditions? [1986], 1)
     A reaction: This is the basic Edgington view. It seems to involve an active thought process, and imagination, rather than being the static semantic relations offered by possible worlds analyses. True conditionals state relationships in the world.
On the supposition view, believe if A,B to the extent that A&B is nearly as likely as A
     Full Idea: Accepting Ramsey's suggestion that 'if' and 'on the supposition that' come to the same thing, we get an equation which says ...you believe if A,B to the extent that you think that A&B is nearly as likely as A.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 3.1)
10. Modality / B. Possibility / 8. Conditionals / f. Pragmatics of conditionals
Truth-functionalists support some conditionals which we assert, but should not actually believe
     Full Idea: There are compounds of conditionals which we confidently assert and accept which, by the lights of the truth-functionalist, we do not have reason to believe true, such as 'If it broke if it was dropped, it was fragile', when it is NOT dropped.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 2.5)
     A reaction: [The example is from Gibbard 1981] The fact that it wasn't dropped only negates the nested antecedent, not the whole antecedent. I suppose it also wasn't broken, and both negations seem to be required.
Does 'If A,B' say something different in each context, because of the possibiites there?
     Full Idea: A pragmatic constraint might say that as different possibilities are live in different conversational settings, a different proposition may be expressed by 'If A,B' in different conversational settings.
     From: Dorothy Edgington (Conditionals (Stanf) [2006], 4.1)
     A reaction: Edgington says that it is only the truth of the proposition, not its content, which changes with context. I'm not so sure. 'If Hitler finds out, we are in trouble' says different things in 1914 and 1944.