19 ideas
| 14352 | '¬', '&', and 'v' are truth functions: the truth of the compound is fixed by the truth of the components [Jackson] |
| Full Idea: It is widely agreed that '¬', '&', and 'v' are 'truth functions': the truth value of a compound sentence formed using them is fully determined by the truth value or values of the component sentences. | |
| From: Frank Jackson (Conditionals [2006], 'Equiv') | |
| A reaction: A candidate for not being a truth function might be a conditional →, where the arrow adds something over and above the propositions it connects. The relationship has an additional truth value? Does A depend on B? |
| 21339 | We want the ontology of relations, not just a formal way of specifying them [Heil] |
| Full Idea: A satisfying account of relations must be ontologically serious. This means refusing to rest content with abstract specifications of relations as sets of ordered n-tuples. | |
| From: John Heil (Relations [2009], Intro) | |
| A reaction: A set of ordered entities would give the extension of a relation, which wouldn't, among other things, explain co-extensive relations (if all the people to my left were also taller than me). Heil's is a general cry from the heart about formal philosophy. |
| 21349 | Two people are indirectly related by height; the direct relation is internal, between properties [Heil] |
| Full Idea: If Simmias is taller than Socrates, they are indirectly related; they are related via their possession of properties that are themselves directly - and internally - related. Hence relational truths are made true by non-relational features of the world. | |
| From: John Heil (Relations [2009], 'Founding') | |
| A reaction: This seems to be a strategy for reducing external relations to internal relations, which are intrinsic to objects, which thus reduces the ontology. Heil is not endorsing it, but cites Kit Fine 2000. The germ of this idea is in Plato. |
| 21340 | Maybe all the other features of the world can be reduced to relations [Heil] |
| Full Idea: A striking idea is that relations are ontologically primary: monadic, non-relational features of the world are constituted by relations. A view of this kind is defended by Peirce, and contemporary 'structural realists' like Ladyman. | |
| From: John Heil (Relations [2009], 'Relational') | |
| A reaction: I can't make sense of this proposal, which seems to offer relations with no relata. What is a relation? What is it made of? How do you individuate two instances of a relations, without reference to the relata? |
| 21348 | In the case of 5 and 6, their relational truthmaker is just the numbers [Heil] |
| Full Idea: We might say that the truthmakers for 'six is greater than five' are six and five themselves. On this view, truthmakers for one class of relational truths are non-relational features of the world. | |
| From: John Heil (Relations [2009], 'Founding') | |
| A reaction: That seems to be a good way of expressing the existence of an internal relation. |
| 21351 | Truthmaking is a clear example of an internal relation [Heil] |
| Full Idea: Truthmaking is a paradigmatic internal relation: if you have a truthbearer, a representation, and you have the world as the truthbearer represents it as being, you have truthmaking, you have the truthbearer's being true. | |
| From: John Heil (Relations [2009], 'Causal') | |
| A reaction: It is nice to have an example of an internal relation other than numbers, and closer to the concrete world. Is the relation between the world and facts about the world the same thing, or another example? |
| 21344 | If R internally relates a and b, and you have a and b, you thereby have R [Heil] |
| Full Idea: A simple way to think about internal relations is: if R internally relates a and b, then, if you have a and b, you thereby have R. If you have six and you have five, you thereby have six's being greater than five. | |
| From: John Heil (Relations [2009], 'External') | |
| A reaction: This seems to work a lot better for abstracta than for physical objects, where I am struggling to think of a parallel example. Parenthood? Temporal relations between things? Acorn and oak? |
| 21350 | If properties are powers, then causal relations are internal relations [Heil] |
| Full Idea: On the conception that properties are powers, it is no longer obvious that causal relations are external relations. Given the powers - all the powers in play - you have the manifestations. | |
| From: John Heil (Relations [2009], 'Causal') | |
| A reaction: This also delivers on a plate the necessity felt to be in causal relations, because the relation is inevitable once you are given the relata. But can you have an accidental (rather than essential) internal relation? Not in the case of numbers. |
| 17945 | Forms are not a theory of universals, but an attempt to explain how predication is possible [Nehamas] |
| Full Idea: The theory of Forms is not a theory of universals but a first attempt to explain how predication, the application of a single term to many objects - now considered one of the most elementary operations of language - is possible. | |
| From: Alexander Nehamas (Introduction to 'Virtues of Authenticity' [1999], p.xxvii) |
| 17946 | Only Tallness really is tall, and other inferior tall things merely participate in the tallness [Nehamas] |
| Full Idea: Only Tallness and nothing else really is tall; everything else merely participates in the Forms and, being excluded from the realm of Being, belongs to the inferior world of Becoming. | |
| From: Alexander Nehamas (Introduction to 'Virtues of Authenticity' [1999], p.xxviii) | |
| A reaction: This is just as weird as the normal view (and puzzle of participation), but at least it makes more sense of 'metachein' (partaking). |
| 14360 | Possible worlds for subjunctives (and dispositions), and no-truth for indicatives? [Jackson] |
| Full Idea: Subjunctive conditionals are intimately connected with dispositional properties and causation. ...Consequently, a position some find attractive is that possible worlds theory applies to subjunctives, while the no-truth theory applies to indicatives. | |
| From: Frank Jackson (Conditionals [2006], 'Indicative') | |
| A reaction: My intuitions are to reject this and favour a unified account, where both sorts of conditionals are mappings of the relationships among the facts of actuality. Nice slogan! |
| 14353 | Modus ponens requires that A→B is F when A is T and B is F [Jackson] |
| Full Idea: Modus ponens is intuitively valid, but in A,A→B|B if A is true and B is false that must be because A→B is false. So A→B is false when A is true and B is false. | |
| From: Frank Jackson (Conditionals [2006], 'Equiv') | |
| A reaction: This is his first step in showing how the truth functional account of A→B acquires its truth table. If you are giving up the truth functional view of conditionals, presumably you are not also going to give up modus ponens? |
| 14354 | When A and B have the same truth value, A→B is true, because A→A is a logical truth [Jackson] |
| Full Idea: (A→A) is a logical truth, so some conditionals with antecedent and consequent the same truth value are true. But if '→' is a truth function, that will be true for all cases. Hence whenever A and B are alike in truth value, (A→B) is true. | |
| From: Frank Jackson (Conditionals [2006], 'Equiv') | |
| A reaction: His second step in demonstrating the truth table for →, assuming it is truth functional. |
| 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] |
| Full Idea: (A&B)→A is a logical truth, but A can be true and B false, so that (A&B) is false. So some conditionals with false antecedent and true consequent are true. If → is a truth function, then whenever A is false and B is true (A→B) is true. | |
| From: Frank Jackson (Conditionals [2006], 'Equiv') | |
| A reaction: This is his third and final step in showing the truth table of → if it is truth functional. |
| 14358 | In the possible worlds account of conditionals, modus ponens and modus tollens are validated [Jackson] |
| 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). | |
| From: Frank Jackson (Conditionals [2006], 'Famous') | |
| 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. |
| 14359 | Only assertions have truth-values, and conditionals are not proper assertions [Jackson] |
| Full Idea: In the no-truth theory of conditionals they have justified assertion or acceptability conditions but not truth conditions. ...The motivation is that only assertions have truth values, and conditionals are arguments, not proper assertions. | |
| From: Frank Jackson (Conditionals [2006], 'No-truth') | |
| A reaction: Once I trim this idea down to its basics, it suddenly looks very persuasive. Except that I am inclined to think that conditional truths do state facts about the world - perhaps as facts about how more basic truths are related to each other. |
| 14357 | Possible worlds account, unlike A⊃B, says nothing about when A is false [Jackson] |
| 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. | |
| From: Frank Jackson (Conditionals [2006], 'Possible') | |
| 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. |
| 14356 | We can't insist that A is relevant to B, as conditionals can express lack of relevance [Jackson] |
| Full Idea: One addition to the truth functional account of conditionals is that A be somehow relevant to B. However, sometimes we use conditionals to express lack of relevance, as in 'If Fred works he will fail, and if Fred doesn't work he will fail'. | |
| From: Frank Jackson (Conditionals [2006], 'Possible') | |
| A reaction: This certainly seems to put paid to an attractive instant solution to the problem. |
| 17944 | 'Episteme' is better translated as 'understanding' than as 'knowledge' [Nehamas] |
| Full Idea: The Greek 'episteme' is usually translated as 'knowledge' but, I argue, closer to our notion of understanding. | |
| From: Alexander Nehamas (Introduction to 'Virtues of Authenticity' [1999], p.xvi) | |
| A reaction: He agrees with Julia Annas on this. I take it to be crucial. See the first sentence of Aristotle's 'Metaphysics'. It is explanation which leads to understanding. |