126 ideas
| 6123 | Empirical investigation can't discover if holes exist, or if two things share a colour [Merricks] |
| Full Idea: Ontology is not empirical, but ontologists do make discoveries; empirical investigation won't discover that holes exist; we see that two things are the same colour, but a philosopher must resolve whether one universal is present in both. | |
| From: Trenton Merricks (Objects and Persons [2003], Pref) | |
| A reaction: This is one of the best, simplest and clearest statements I have encountered of the autonomy of philosophy. One may, of course, respond by saying 'who cares?', but then who cares about quarks, or the economy of the Spanish Empire? |
| 19215 | Arguers often turn the opponent's modus ponens into their own modus tollens [Merricks] |
| Full Idea: There is a seasoned method of turning your opponent's modus ponens into your own modus tollens. | |
| From: Trenton Merricks (Propositions [2015], 5.VII) | |
| A reaction: That is, they say 'if he's coming he'll be hear by now, and he's definitely coming', to which you say 'I'm afraid he's not here, so he obviously isn't coming after all'. They say if-A-then-B, and A, so B. You say not-B, so you're wrong about A. |
| 14415 | A ground must be about its truth, and not just necessitate it [Merricks] |
| Full Idea: A ground does not merely necessitate its truth. A ground is also what its truth is appropriately about. | |
| From: Trenton Merricks (Truth and Ontology [2007], 7.II) |
| 14408 | Truthmaker needs truths to be 'about' something, and that is often unclear [Merricks] |
| Full Idea: It is not always obvious what (if anything) a truth is about, in the sense of 'about' relevant to Truthmaker and truth-supervenient-on-being. Prior says 'Queen Anne is dead' is not about Queen Anne, and may be about the Earth. | |
| From: Trenton Merricks (Truth and Ontology [2007], 6.III) | |
| A reaction: A very nice and rather subtle objection to the Truthmaker thesis. Specifying the truthmaker for a given truth looks like a doddle in simple cases, but clearly it can become extremely elusive in other cases. |
| 14398 | Truthmaker says if an entity is removed, some nonexistence truthmaker must replace it [Merricks] |
| Full Idea: Truthmaker makes it impossible simply to remove an entity. One must always replace it with something else; namely, a truthmaker for the claim that that entity does not exist. | |
| From: Trenton Merricks (Truth and Ontology [2007], 4.I-3) | |
| A reaction: This is a particularly strong and persuasive argument from Merricks against the truthmaker view. Clearly the truthmaker for non-existence can't be there when it exists, and the destruction bringing the negative truthmaker into existence sounds odd. |
| 14403 | If Truthmaker says each truth is made by the existence of something, the theory had de re modality at is core [Merricks] |
| Full Idea: Truthmaker says that, for each truth, there is something that, by its mere existence, makes that truth true, …so Truthmaker has de re modality at its core. | |
| From: Trenton Merricks (Truth and Ontology [2007], 5.III) | |
| A reaction: I have no problem with de re modality, so this doesn't bother me. Merricks brings out nicely the baggage which you must carry if you are a Truthmaker. |
| 14395 | If a ball changes from red to white, Truthmaker says some thing must make the change true [Merricks] |
| Full Idea: If a single ball goes from being red to being white, Truthmaker implies that something exists which makes it true that the second thing follows the first. | |
| From: Trenton Merricks (Truth and Ontology [2007], 3.V) |
| 14397 | Truthmaker demands not just a predication, but an existing state of affairs with essential ingredients [Merricks] |
| Full Idea: The claim 'that Fido is brown' seems to demand only a brown Fido, but Truthmaker demands more. It demands both that a state of affairs along the lines of 'Fido's being brown' exists, and also that this state has its constituents essentially. | |
| From: Trenton Merricks (Truth and Ontology [2007], 4.I) | |
| A reaction: One would need to reread Merricks to get this clear, but my instinct is that the two scenarios are not very different. 'A brown Fido' would require Fido to be necessarily brown to do the job. |
| 14396 | If 'truth supervenes on being', worlds with the same entities, properties and relations have the same truths [Merricks] |
| Full Idea: 'Truth supervenes on being' says that any two possible worlds alike with respect to what entities exist and which properties (and relations) each of those entities exemplifies are thereby alike with respect to what is true. | |
| From: Trenton Merricks (Truth and Ontology [2007], 4) | |
| A reaction: Merricks says this view is found in early Wittgenstein, as well as in David Lewis. He suggests that this is a weaker and more plausible thesis than the full commitment to truthmakers. It still allows some truths to lack truthmakers. Sounds plausible. |
| 14400 | If truth supervenes on being, that won't explain why truth depends on being [Merricks] |
| Full Idea: If 'truth supervenes on being' aims to articulate the idea that truth depends on being, it must say more than that truth supervenes on being. | |
| From: Trenton Merricks (Truth and Ontology [2007], 4.VI) | |
| A reaction: This is a perennial problem with supervenience accounts, such as the supervenience of beauty on the object, or of mind on brain. |
| 14394 | It is implausible that claims about non-existence are about existing things [Merricks] |
| Full Idea: It is implausible that a claim asserting that a thing fails to exist is made true by - and so is appropriately about - some other, existing thing. | |
| From: Trenton Merricks (Truth and Ontology [2007], 3.V) |
| 14390 | Truthmaker isn't the correspondence theory, because it offers no analysis of truth [Merricks] |
| Full Idea: Because Truthmaker offers no analysis of being true, Truthmaker is not the correspondence theory of truth. | |
| From: Trenton Merricks (Truth and Ontology [2007], 1.IV) | |
| A reaction: I'm not convinced that the correspondence theory offers an 'analysis' of truth. It doesn't seem to do much more than offer a word which suggests an analogy with some relation in the world. |
| 14412 | Speculations about non-existent things are not about existent things, so Truthmaker is false [Merricks] |
| Full Idea: That 'there might have been a dozen more fundamental particles' is true, but not appropriately about any existing entities or their properties. Since Truthmaker says that all truths are about existing entities, it must be false. | |
| From: Trenton Merricks (Truth and Ontology [2007], 6.VI) | |
| A reaction: Since I don't necessarily agree that 'there might have been a dozen more fundamental particles' (see Scientific Essentialism), and I take the disagreement to have some basis, I doubt this idea. What stops 'there could be circular squares' from being true? |
| 14414 | I am a truthmaker for 'that a human exists', but is it about me? [Merricks] |
| Full Idea: I am a truthmaker for 'that a human exists', but it is not obvious that that proposition is thus about me. | |
| From: Trenton Merricks (Truth and Ontology [2007], 7.I) | |
| A reaction: This is part of the general rather good objection that it is often unclear what a truth is 'about' (Idea 14408). The original Gettier examples about justification illustrate this problem. They make things true, in a surprising way. |
| 14418 | Being true is not a relation, it is a primitive monadic property [Merricks] |
| Full Idea: Being true is not a relation. …Being true is a monadic property. …Being true is a primitive property. | |
| From: Trenton Merricks (Truth and Ontology [2007], 8.IV) | |
| A reaction: Even after reading Merricks on this, I am not sure I understand it. If a single sentence floats in the void, it is hard to see how the 'monadic' property of truth could accrue to it. |
| 14391 | If the correspondence theory is right, then necessary truths must correspond to something [Merricks] |
| Full Idea: Suppose for the sake of argument that the correspondence theory is correct. Then it is analytic that each necessary truth, in virtue of being true, corresponds to something. | |
| From: Trenton Merricks (Truth and Ontology [2007], 2.II) | |
| A reaction: The sort of nice simple observation for which I admire Merricks. You don't have to give up on the correspondence theory at this point, but you will have to go through with some substantial metaphysics to keep it afloat. |
| 19205 | 'Snow is white' only contingently expresses the proposition that snow is white [Merricks] |
| Full Idea: It is contingently true that 'snow is white' expresses the proposition that snow is white. | |
| From: Trenton Merricks (Propositions [2015], 1.V n14) | |
| A reaction: Tarski stuck to sentences, but Merricks rightly argues that truth concerns propositions, not sentences. Sentences are subservient entities - mere tools used to express what matters, which is our thoughts (say I). |
| 14419 | Deflationism just says there is no property of being truth [Merricks] |
| Full Idea: I take 'deflationism' to be nothing other than the claim that there is no property of being true. | |
| From: Trenton Merricks (Truth and Ontology [2007], 8.V) |
| 9535 | 'Contradictory' propositions always differ in truth-value [Lemmon] |
| Full Idea: Two propositions are 'contradictory' if they are never both true and never both false either, which means that ¬(A↔B) is a tautology. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.3) |
| 9511 | We write the conditional 'if P (antecedent) then Q (consequent)' as P→Q [Lemmon] |
| Full Idea: We write 'if P then Q' as P→Q. This is called a 'conditional', with P as its 'antecedent', and Q as its 'consequent'. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.2) | |
| A reaction: P→Q can also be written as ¬P∨Q. |
| 9509 | That proposition that both P and Q is their 'conjunction', written P∧Q [Lemmon] |
| Full Idea: If P and Q are any two propositions, the proposition that both P and Q is called the 'conjunction' of P and Q, and is written P∧Q. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.3) | |
| A reaction: [I use the more fashionable inverted-v '∧', rather than Lemmon's '&', which no longer seems to be used] P∧Q can also be defined as ¬(¬P∨¬Q) |
| 9514 | If A and B are 'interderivable' from one another we may write A -||- B [Lemmon] |
| Full Idea: If we say that A and B are 'interderivable' from one another (that is, A |- B and B |- A), then we may write A -||- B. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9508 | The sign |- may be read as 'therefore' [Lemmon] |
| Full Idea: I introduce the sign |- to mean 'we may validly conclude'. To call it the 'assertion sign' is misleading. It may conveniently be read as 'therefore'. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.2) | |
| A reaction: [Actually no gap between the vertical and horizontal strokes of the sign] As well as meaning 'assertion', it may also mean 'it is a theorem that' (with no proof shown). |
| 9510 | That proposition that either P or Q is their 'disjunction', written P∨Q [Lemmon] |
| Full Idea: If P and Q are any two propositions, the proposition that either P or Q is called the 'disjunction' of P and Q, and is written P∨Q. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.3) | |
| A reaction: This is inclusive-or (meaning 'P, or Q, or both'), and not exlusive-or (Boolean XOR), which means 'P, or Q, but not both'. The ∨ sign is sometimes called 'vel' (Latin). |
| 9512 | We write the 'negation' of P (not-P) as ¬ [Lemmon] |
| Full Idea: We write 'not-P' as ¬P. This is called the 'negation' of P. The 'double negation' of P (not not-P) would be written as ¬¬P. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.2) | |
| A reaction: Lemmons use of -P is no longer in use for 'not'. A tilde sign (squiggle) is also used for 'not', but some interpreters give that a subtly different meaning (involving vagueness). The sign ¬ is sometimes called 'hook' or 'corner'. |
| 9513 | We write 'P if and only if Q' as P↔Q; it is also P iff Q, or (P→Q)∧(Q→P) [Lemmon] |
| Full Idea: We write 'P if and only if Q' as P↔Q. It is called the 'biconditional', often abbreviate in writing as 'iff'. It also says that P is both sufficient and necessary for Q, and may be written out in full as (P→Q)∧(Q→P). | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.4) | |
| A reaction: If this symbol is found in a sequence, the first move in a proof is to expand it to the full version. |
| 9516 | A 'well-formed formula' follows the rules for variables, ¬, →, ∧, ∨, and ↔ [Lemmon] |
| Full Idea: A 'well-formed formula' of the propositional calculus is a sequence of symbols which follows the rules for variables, ¬, →, ∧, ∨, and ↔. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.1) |
| 9517 | The 'scope' of a connective is the connective, the linked formulae, and the brackets [Lemmon] |
| Full Idea: The 'scope' of a connective in a certain formula is the formulae linked by the connective, together with the connective itself and the (theoretically) encircling brackets | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.1) |
| 9518 | A 'theorem' is the conclusion of a provable sequent with zero assumptions [Lemmon] |
| Full Idea: A 'theorem' of logic is the conclusion of a provable sequent in which the number of assumptions is zero. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) | |
| A reaction: This is what Quine and others call a 'logical truth'. |
| 9528 | A wff is a 'tautology' if all assignments to variables result in the value T [Lemmon] |
| Full Idea: If a well-formed formula of propositional calculus takes the value T for all possible assignments of truth-values to its variables, it is said to be a 'tautology'. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.3) |
| 9529 | A wff is 'inconsistent' if all assignments to variables result in the value F [Lemmon] |
| Full Idea: If a well-formed formula of propositional calculus takes the value F for all possible assignments of truth-values to its variables, it is said to be 'inconsistent'. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.3) |
| 9531 | 'Contrary' propositions are never both true, so that ¬(A∧B) is a tautology [Lemmon] |
| Full Idea: If A and B are expressible in propositional calculus notation, they are 'contrary' if they are never both true, which may be tested by the truth-table for ¬(A∧B), which is a tautology if they are contrary. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.3) |
| 9534 | Two propositions are 'equivalent' if they mirror one another's truth-value [Lemmon] |
| Full Idea: Two propositions are 'equivalent' if whenever A is true B is true, and whenever B is true A is true, in which case A↔B is a tautology. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.3) |
| 9519 | A 'substitution-instance' is a wff formed by consistent replacing variables with wffs [Lemmon] |
| Full Idea: A 'substitution-instance' is a wff which results by replacing one or more variables throughout with the same wffs (the same wff replacing each variable). | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) |
| 9530 | A wff is 'contingent' if produces at least one T and at least one F [Lemmon] |
| Full Idea: If a well-formed formula of propositional calculus takes at least one T and at least one F for all the assignments of truth-values to its variables, it is said to be 'contingent'. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.3) |
| 9533 | A 'implies' B if B is true whenever A is true (so that A→B is tautologous) [Lemmon] |
| Full Idea: One proposition A 'implies' a proposition B if whenever A is true B is true (but not necessarily conversely), which is only the case if A→B is tautologous. Hence B 'is implied' by A. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.3) |
| 9532 | 'Subcontrary' propositions are never both false, so that A∨B is a tautology [Lemmon] |
| Full Idea: If A and B are expressible in propositional calculus notation, they are 'subcontrary' if they are never both false, which may be tested by the truth-table for A∨B, which is a tautology if they are subcontrary. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.3) |
| 9394 | MPP: Given A and A→B, we may derive B [Lemmon] |
| Full Idea: Modus Ponendo Ponens (MPP): Given A and A→B, we may derive B as a conclusion. B will rest on any assumptions that have been made. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9393 | A: we may assume any proposition at any stage [Lemmon] |
| Full Idea: Assumptions (A): any proposition may be introduced at any stage of a proof. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9399 | ∧E: Given A∧B, we may derive either A or B separately [Lemmon] |
| Full Idea: And-Elimination (∧E): Given A∧B, we may derive either A or B separately. The conclusions will depend on the assumptions of the premiss. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9400 | ∨I: Given either A or B separately, we may derive A∨B [Lemmon] |
| Full Idea: Or-Introduction (∨I): Given either A or B separately, we may derive A∨B as conclusion. This depends on the assumption of the premisses. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9402 | RAA: If assuming A will prove B∧¬B, then derive ¬A [Lemmon] |
| Full Idea: Reduction ad Absurdum (RAA): Given a proof of B∧¬B from A as assumption, we may derive ¬A as conclusion, depending on the remaining assumptions (if any). | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9401 | ∨E: Derive C from A∨B, if C can be derived both from A and from B [Lemmon] |
| Full Idea: Or-Elimination (∨E): Given A∨B, we may derive C if it is proved from A as assumption and from B as assumption. This will also depend on prior assumptions. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9395 | MTT: Given ¬B and A→B, we derive ¬A [Lemmon] |
| Full Idea: Modus Tollendo Tollens (MTT): Given ¬B and A→B, we derive ¬A as a conclusion. ¬A depends on any assumptions that have been made | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9396 | DN: Given A, we may derive ¬¬A [Lemmon] |
| Full Idea: Double Negation (DN): Given A, we may derive ¬¬A as a conclusion, and vice versa. The conclusion depends on the assumptions of the premiss. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9397 | CP: Given a proof of B from A as assumption, we may derive A→B [Lemmon] |
| Full Idea: Conditional Proof (CP): Given a proof of B from A as assumption, we may derive A→B as conclusion, on the remaining assumptions (if any). | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9398 | ∧I: Given A and B, we may derive A∧B [Lemmon] |
| Full Idea: And-Introduction (&I): Given A and B, we may derive A∧B as conclusion. This depends on their previous assumptions. | |
| From: E.J. Lemmon (Beginning Logic [1965], 1.5) |
| 9521 | 'Modus tollendo ponens' (MTP) says ¬P, P ∨ Q |- Q [Lemmon] |
| Full Idea: 'Modus tollendo ponens' (MTP) says that if a disjunction holds and also the negation of one of its disjuncts, then the other disjunct holds. Thus ¬P, P ∨ Q |- Q may be introduced as a theorem. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) | |
| A reaction: Unlike Modus Ponens and Modus Tollens, this is a derived rule. |
| 9522 | 'Modus ponendo tollens' (MPT) says P, ¬(P ∧ Q) |- ¬Q [Lemmon] |
| Full Idea: 'Modus ponendo tollens' (MPT) says that if the negation of a conjunction holds and also one of its conjuncts, then the negation of the other conjunct holds. Thus P, ¬(P ∧ Q) |- ¬Q may be introduced as a theorem. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) | |
| A reaction: Unlike Modus Ponens and Modus Tollens, this is a derived rule. |
| 9526 | We can change conjunctions into negated conditionals with P→Q -||- ¬(P → ¬Q) [Lemmon] |
| Full Idea: The proof that P∧Q -||- ¬(P → ¬Q) is useful for enabling us to change conjunctions into negated conditionals. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) |
| 9527 | The Distributive Laws can rearrange a pair of conjunctions or disjunctions [Lemmon] |
| Full Idea: The Distributive Laws say that P ∧ (Q∨R) -||- (P∧Q) ∨ (P∧R), and that P ∨ (Q∨R) -||- (P∨Q) ∧ (P∨R) | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) |
| 9523 | De Morgan's Laws make negated conjunctions/disjunctions into non-negated disjunctions/conjunctions [Lemmon] |
| Full Idea: The forms of De Morgan's Laws [P∨Q -||- ¬(¬P ∧ ¬Q); ¬(P∨Q) -||- ¬P ∧ ¬Q; ¬(P∧Q) -||- ¬P ∨ ¬Q); P∧Q -||- ¬(¬P∨¬Q)] transform negated conjunctions and disjunctions into non-negated disjunctions and conjunctions respectively. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) |
| 9524 | We can change conditionals into disjunctions with P→Q -||- ¬P ∨ Q [Lemmon] |
| Full Idea: The proof that P→Q -||- ¬P ∨ Q is useful for enabling us to change conditionals into disjunctions. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) |
| 9525 | We can change conditionals into negated conjunctions with P→Q -||- ¬(P ∧ ¬Q) [Lemmon] |
| Full Idea: The proof that P→Q -||- ¬(P ∧ ¬Q) is useful for enabling us to change conditionals into negated conjunctions | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) |
| 9537 | Truth-tables are good for showing invalidity [Lemmon] |
| Full Idea: The truth-table approach enables us to show the invalidity of argument-patterns, as well as their validity. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.4) |
| 9538 | A truth-table test is entirely mechanical, but this won't work for more complex logic [Lemmon] |
| Full Idea: A truth-table test is entirely mechanical, ..and in propositional logic we can even generate proofs mechanically for tautological sequences, ..but this mechanical approach breaks down with predicate calculus, and proof-discovery is an imaginative process. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.5) |
| 9536 | If any of the nine rules of propositional logic are applied to tautologies, the result is a tautology [Lemmon] |
| Full Idea: If any application of the nine derivation rules of propositional logic is made on tautologous sequents, we have demonstrated that the result is always a tautologous sequent. Thus the system is consistent. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.4) | |
| A reaction: The term 'sound' tends to be used now, rather than 'consistent'. See Lemmon for the proofs of each of the nine rules. |
| 9539 | Propositional logic is complete, since all of its tautologous sequents are derivable [Lemmon] |
| Full Idea: A logical system is complete is all expressions of a specified kind are derivable in it. If we specify tautologous sequent-expressions, then propositional logic is complete, because we can show that all tautologous sequents are derivable. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.5) | |
| A reaction: [See Lemmon 2.5 for details of the proofs] |
| 13902 | 'Gm' says m has property G, and 'Pmn' says m has relation P to n [Lemmon] |
| Full Idea: A predicate letter followed by one name expresses a property ('Gm'), and a predicate-letter followed by two names expresses a relation ('Pmn'). We could write 'Pmno' for a complex relation like betweenness. | |
| From: E.J. Lemmon (Beginning Logic [1965], 3.1) |
| 13911 | The 'symbols' are bracket, connective, term, variable, predicate letter, reverse-E [Lemmon] |
| Full Idea: I define a 'symbol' (of the predicate calculus) as either a bracket or a logical connective or a term or an individual variable or a predicate-letter or reverse-E (∃). | |
| From: E.J. Lemmon (Beginning Logic [1965], 4.1) |
| 13909 | Write '(∀x)(...)' to mean 'take any x: then...', and '(∃x)(...)' to mean 'there is an x such that....' [Lemmon] |
| Full Idea: Just as '(∀x)(...)' is to mean 'take any x: then....', so we write '(∃x)(...)' to mean 'there is an x such that....' | |
| From: E.J. Lemmon (Beginning Logic [1965], 3.1) | |
| A reaction: [Actually Lemmon gives the universal quantifier symbol as '(x)', but the inverted A ('∀') seems to have replaced it these days] |
| 13910 | Our notation uses 'predicate-letters' (for 'properties'), 'variables', 'proper names', 'connectives' and 'quantifiers' [Lemmon] |
| Full Idea: Quantifier-notation might be thus: first, render into sentences about 'properties', and use 'predicate-letters' for them; second, introduce 'variables'; third, introduce propositional logic 'connectives' and 'quantifiers'. Plus letters for 'proper names'. | |
| From: E.J. Lemmon (Beginning Logic [1965], 3.1) |
| 13904 | Universal Elimination (UE) lets us infer that an object has F, from all things having F [Lemmon] |
| Full Idea: Our rule of universal quantifier elimination (UE) lets us infer that any particular object has F from the premiss that all things have F. It is a natural extension of &E (and-elimination), as universal propositions generally affirm a complex conjunction. | |
| From: E.J. Lemmon (Beginning Logic [1965], 3.2) |
| 13901 | Predicate logic uses propositional connectives and variables, plus new introduction and elimination rules [Lemmon] |
| Full Idea: In predicate calculus we take over the propositional connectives and propositional variables - but we need additional rules for handling quantifiers: four rules, an introduction and elimination rule for the universal and existential quantifiers. | |
| From: E.J. Lemmon (Beginning Logic [1965]) | |
| A reaction: This is Lemmon's natural deduction approach (invented by Gentzen), which is largely built on introduction and elimination rules. |
| 13903 | Universal elimination if you start with the universal, introduction if you want to end with it [Lemmon] |
| Full Idea: The elimination rule for the universal quantifier concerns the use of a universal proposition as a premiss to establish some conclusion, whilst the introduction rule concerns what is required by way of a premiss for a universal proposition as conclusion. | |
| From: E.J. Lemmon (Beginning Logic [1965], 3.2) | |
| A reaction: So if you start with the universal, you need to eliminate it, and if you start without it you need to introduce it. |
| 13906 | With finite named objects, we can generalise with &-Intro, but otherwise we need ∀-Intro [Lemmon] |
| Full Idea: If there are just three objects and each has F, then by an extension of &I we are sure everything has F. This is of no avail, however, if our universe is infinitely large or if not all objects have names. We need a new device, Universal Introduction, UI. | |
| From: E.J. Lemmon (Beginning Logic [1965], 3.2) |
| 13908 | UE all-to-one; UI one-to-all; EI arbitrary-to-one; EE proof-to-one [Lemmon] |
| Full Idea: Univ Elim UE - if everything is F, then something is F; Univ Intro UI - if an arbitrary thing is F, everything is F; Exist Intro EI - if an arbitrary thing is F, something is F; Exist Elim EE - if a proof needed an object, there is one. | |
| From: E.J. Lemmon (Beginning Logic [1965], 3.3) | |
| A reaction: [My summary of Lemmon's four main rules for predicate calculus] This is the natural deduction approach, of trying to present the logic entirely in terms of introduction and elimination rules. See Bostock on that. |
| 13905 | If there is a finite domain and all objects have names, complex conjunctions can replace universal quantifiers [Lemmon] |
| Full Idea: If all objects in a given universe had names which we knew and there were only finitely many of them, then we could always replace a universal proposition about that universe by a complex conjunction. | |
| From: E.J. Lemmon (Beginning Logic [1965], 3.2) |
| 13900 | 'Some Frenchmen are generous' is rendered by (∃x)(Fx→Gx), and not with the conditional → [Lemmon] |
| Full Idea: It is a common mistake to render 'some Frenchmen are generous' by (∃x)(Fx→Gx) rather than the correct (∃x)(Fx&Gx). 'All Frenchmen are generous' is properly rendered by a conditional, and true if there are no Frenchmen. | |
| From: E.J. Lemmon (Beginning Logic [1965], 3.1) | |
| A reaction: The existential quantifier implies the existence of an x, but the universal quantifier does not. |
| 19209 | Simple Quantified Modal Logc doesn't work, because the Converse Barcan is a theorem [Merricks] |
| Full Idea: Logical consequence guarantees preservation of truth. The Converse Barcan, a theorem of Simple Quantified Modal Logic, says that an obvious truth implies an obvious falsehood. So SQML gets logical consequence wrong. So SQML is mistaken. | |
| From: Trenton Merricks (Propositions [2015], 2.V) | |
| A reaction: I admire this. The Converse Barcan certainly strikes me as wrong (Idea 19208). Merricks grasps this nettle. Williamson grasps the other nettle. Most people duck the issue, I suspect. Merricks says later that domains are the problem. |
| 19208 | The Converse Barcan implies 'everything exists necessarily' is a consequence of 'necessarily, everything exists' [Merricks] |
| Full Idea: The Converse Barcan Formula has a startling result. Simple Quantified Modal Logic (SQML) has the following as a theorem: □∀xFx → ∀x□Fx. So 'everything exists necessarily' is a consequence of 'necessarily, everything exists'. | |
| From: Trenton Merricks (Propositions [2015], 2.V) | |
| A reaction: He says this is blatantly wrong. Williamson is famous for defending it. I think I'm with Merricks on this one. |
| 9520 | The paradoxes of material implication are P |- Q → P, and ¬P |- P → Q [Lemmon] |
| Full Idea: The paradoxes of material implication are P |- Q → P, and ¬P |- P → Q. That is, since Napoleon was French, then if the moon is blue then Napoleon was French; and since Napoleon was not Chinese, then if Napoleon was Chinese, the moon is blue. | |
| From: E.J. Lemmon (Beginning Logic [1965], 2.2) | |
| A reaction: This is why the symbol → does not really mean the 'if...then' of ordinary English. Russell named it 'material implication' to show that it was a distinctively logical operator. |
| 19207 | Sentence logic maps truth values; predicate logic maps objects and sets [Merricks] |
| Full Idea: The models for sentential logic map sentences to truth-values. The models for predicate logic map parts of sentences to objects and sets. | |
| From: Trenton Merricks (Propositions [2015], 2.II) | |
| A reaction: Logic books rarely tell you important things like this. That is why this database is so incredibly important! You will never understand the subject if you don't collect together the illuminating asides of discussion. They say it all so much more simply. |
| 14393 | The totality state is the most plausible truthmaker for negative existential truths [Merricks] |
| Full Idea: The claim that the totality state is the sole truthmaker for negative existential truths emerges as the best position for a truthmaker theorist. | |
| From: Trenton Merricks (Truth and Ontology [2007], 3.III) |
| 6143 | Prolonged events don't seem to endure or exist at any particular time [Merricks] |
| Full Idea: That events endure is difficult to reconcile with the claim that, say, the American Civil War existed; for such an event seems never to have been 'wholly present' at any single time. | |
| From: Trenton Merricks (Objects and Persons [2003], §3 n14) | |
| A reaction: A nice problem example for those who, like Kim, want their ontology to include events. Personally I am happy to allow some vagueness here. The Civil War only became an 'event' on the day it finished. An event's time need not be an instant. |
| 6135 | A crumbling statue can't become vague, because vagueness is incoherent [Merricks] |
| Full Idea: Some would say that annihilating grains of stone from the statue of David (playing the 'Sorites Game') could never make its identity vague, because metaphysical vagueness is simply unintelligible. | |
| From: Trenton Merricks (Objects and Persons [2003], §2.II) | |
| A reaction: He cites Russell, Dummett and Lewis in support. But Russell is a logical atomist, and Lewis says identity is composition. It strikes me as obvious that identity can be vague; the alternative is the absurdities of the Sorites paradox. |
| 14413 | Some properties seem to be primitive, but others can be analysed [Merricks] |
| Full Idea: Some properties (perhaps negative charge, or the relation of identity) admit of no analysis, and so are primitive. But others are analysable, and so not primitive | |
| From: Trenton Merricks (Truth and Ontology [2007], 7.I) |
| 6145 | Intrinsic properties are those an object still has even if only that object exists [Merricks] |
| Full Idea: Intrinsic properties are, by and large, those properties that an object can exemplify even if that object and its parts (if any) are the only objects that exist. | |
| From: Trenton Merricks (Objects and Persons [2003], §4.I) | |
| A reaction: This leads to all sorts of properties that seemed intrinsic turning out to be relational. In what sense would a single object have mass, or impenetrability? |
| 14416 | An object can have a disposition when the revelant conditional is false [Merricks] |
| Full Idea: It is possible for an object to have a disposition even though the relevant conditional is false. | |
| From: Trenton Merricks (Truth and Ontology [2007], 7.III) | |
| A reaction: This is the now standard observation that finks (killing the disposition) and antidotes (blocking the effect of the disposition) can intervene, as in safety mechanisms in electrical gadgets. There may be replies available here. |
| 6124 | I say that most of the objects of folk ontology do not exist [Merricks] |
| Full Idea: I argue against the existence of most of the objects alleged to exist by what we might call 'folk ontology'. | |
| From: Trenton Merricks (Objects and Persons [2003], §1) | |
| A reaction: This is the programme for Merricks's heroic book, denying (quite plausibly) the need for large objects in our ontology. It seems that ontology must multiply its entities prodigiously, or else be austere in the extreme. Is there no middle way? |
| 6134 | Is swimming pool water an object, composed of its mass or parts? [Merricks] |
| Full Idea: Some - such as those who endorse unrestricted composition or those who believe in a kind of entity called 'a mass' - say that 'the water in the swimming pool' refers to a big material object. | |
| From: Trenton Merricks (Objects and Persons [2003], §2.I) | |
| A reaction: A well-chosen example to support his thesis that large objects don't (strictly) exist. We certainly must not say (in Quine fashion) that we must accept the ontology of our phrases. I cut nature at the joints, and I say a pool is an obvious joint. |
| 14392 | Fregeans say 'hobbits do not exist' is just 'being a hobbit' is not exemplified [Merricks] |
| Full Idea: A Fregean about existence claims would say that 'that hobbits do not exist' is nothing other than the claim that 'being a hobbit' is not exemplified. | |
| From: Trenton Merricks (Truth and Ontology [2007], 3.II) | |
| A reaction: 'My passport has ceased to exist' seems to be a bit more dramatic than a relationship with a concept. |
| 6125 | We can eliminate objects without a commitment to simples [Merricks] |
| Full Idea: Eliminativism about physical objects does not require a commitment to (or against) simples. | |
| From: Trenton Merricks (Objects and Persons [2003], §1.I) | |
| A reaction: His strategy is to eliminate objects in favour of whatever it is (an unknown) to which objects actually reduce. His point seems to be clearly correct, just as I might eliminate 'life' from my ontology, without quite knowing what it is. |
| 14229 | Merricks agrees that there are no composite objects, but offers a different semantics [Merricks, by Liggins] |
| Full Idea: Merricks agrees with van Inwagen that there are no composite objects, but disagrees with him about the semantics of talk about material objects. | |
| From: report of Trenton Merricks (Objects and Persons [2003]) by David Liggins - Nihilism without Self-Contradiction 4 | |
| A reaction: Van Inwagen has one semantics for folk talk, and another semantics 'for the philosophy room'. Merricks seems to have an error theory of folk semantics (i.e. the folk don't understand what they are saying). |
| 6142 | The 'folk' way of carving up the world is not intrinsically better than quite arbitrary ways [Merricks] |
| Full Idea: It is hard to see why the folk way of carving up the material world should - barring further argument - be elevated to a loftier status than the unrestricted compositionist way. | |
| From: Trenton Merricks (Objects and Persons [2003], §3.III) | |
| A reaction: There are some right ways to carve up the world, though there is also the capacity to be quite arbitrary, if it is useful, or even amusing. Thus Cyprus is an island (fact), Britons are a nation (useful), and Arsenal fans are sad (amusing). |
| 14472 | If atoms 'arranged baseballwise' break a window, that analytically entails that a baseball did it [Merricks, by Thomasson] |
| Full Idea: Given the proper understanding of 'arranged baseballwise', the fact that atoms arranged baseballwise are causally relevant to a shattering analytically entails that a baseball is. | |
| From: report of Trenton Merricks (Objects and Persons [2003], 3) by Amie L. Thomasson - Ordinary Objects 01.3 | |
| A reaction: This is the key argument of Thomasson's book. Presumably, following Idea 14471, 'I bought some atoms arranged baseballwise' is held to entail 'I bought a baseball'. That seems to beg the question against Van Inwagen and Merricks. |
| 14469 | Overdetermination: the atoms do all the causing, so the baseball causes no breakage [Merricks] |
| Full Idea: The Overdetermination Argument: a baseball is irrelevant to whether its atoms shatter a window, the shattering is caused by the atoms in concert, the shattering is not overdetermined, so if the baseball exists it doesn't cause the shattering. | |
| From: Trenton Merricks (Objects and Persons [2003], 3) | |
| A reaction: An obvious thought is that no individual atom does any sort of breaking at all - it is only when they act as a team, and an appropriate name for the team is a 'baseball', and the team is real. |
| 6137 | Clay does not 'constitute' a statue, as they have different persistence conditions (flaking, squashing) [Merricks] |
| Full Idea: A statue is not identical with its constituent lump of clay because they have different persistence conditions; the statue, but not the lump, could survive the loss of a few smallish bits, and the lump, but not the statue, could survive being squashed. | |
| From: Trenton Merricks (Objects and Persons [2003], §2.III) | |
| A reaction: I don't see why a lump can't survive losing a few bits (if the lump never had a precise identity), but it is hard to argue that squashing is a problem. However, presumably the identity (or constitution) between lump and statue is not a necessity. |
| 6127 | 'Unrestricted composition' says any two things can make up a third thing [Merricks] |
| Full Idea: If my dog and the top half of my tree compose an object, this is defended under the title of 'unrestricted (universal) composition', the thesis that any two things compose something. | |
| From: Trenton Merricks (Objects and Persons [2003], §1.II) | |
| A reaction: David Lewis is cited amongst those defending this thesis. My intuition is against this thesis, because I think identity is partly dictated by nature, and is not entirely conventional. You can force an identity, but you feel the 'restriction'. |
| 6131 | Composition as identity is false, as identity is never between a single thing and many things [Merricks] |
| Full Idea: One of the most obvious facts about identity is that it holds one-one (John and Mr Smith) and perhaps many-many (John+Mary and Mr Smith+Miss Jones), but never one-many. It follows that composition as identity (things are their parts) is false. | |
| From: Trenton Merricks (Objects and Persons [2003], §1.IV) | |
| A reaction: This assumes that 'having identity' and 'being identical to' are the same concept. I agree with his conclusion, but am not convinced by the argument. I'm not even quite clear why John and May can't be identical to the Smiths. |
| 6132 | Composition as identity is false, as it implies that things never change their parts [Merricks] |
| Full Idea: Composition as identity implies that no persisting object ever changes its parts, which is clearly false, so composition as identity is false. | |
| From: Trenton Merricks (Objects and Persons [2003], §1.IV) | |
| A reaction: Presumably Lewis can say that when a thing subtly changes its parts, it really does lose its strict identity, but becomes another 'time-slice' or close 'counterpart' of the original object. This is a coherent view, but I disagree. I'm a believer. |
| 6141 | There is no visible difference between statues, and atoms arranged statuewise [Merricks] |
| Full Idea: If we imagine a world like ours except that, while there are atoms arranged statuewise in that world, there are no statues, ...no amount of looking around could distinguish that imagined world from ours. | |
| From: Trenton Merricks (Objects and Persons [2003], §2.V) | |
| A reaction: This is one of his arguments for ontological eliminativism about physical objects. If we accept the argument, it will wreak havoc with our entire ontology, and we will end up anti-realists. I say you have to see statues - you just can't miss them. |
| 6130 | 'Composition' says things are their parts; 'constitution' says a whole substance is an object [Merricks] |
| Full Idea: Composition as identity claims that a single object is identical with the many parts it comprises; constitution as identity says that a single object (a statue) is identical with a single object (clay) that 'constitutes' it. | |
| From: Trenton Merricks (Objects and Persons [2003], §1 n11) | |
| A reaction: The constitution view has been utilised (by Lynn Rudder Baker) to give an account of personal identity as constituted by a human body. Neither sounds quite right to me; the former view misses something about reality; the latter doesn't explain much. |
| 6138 | It seems wrong that constitution entails that two objects are wholly co-located [Merricks] |
| Full Idea: Many philosophers deny that two numerically distinct physical objects could be 'wholly co-located'. | |
| From: Trenton Merricks (Objects and Persons [2003], §2.III) | |
| A reaction: A fish can be located in a river; the Appenines can be located in Italy. If you accept the objection you will probably have to accept identity-as-composition, or object-eliminativism. One object can have two causal roles, supporting two identities. |
| 6128 | Objects decompose (it seems) into non-overlapping parts that fill its whole region [Merricks] |
| Full Idea: Intuitively, an object's parts at one level of decomposition are parts of that object that do not overlap and that, collectively, fill the whole region the object fills. | |
| From: Trenton Merricks (Objects and Persons [2003], §1.II) | |
| A reaction: A nice case where 'intuition' must be cited as the basis for the claim, and yet it is hard to see how anyone could possibly disagree. Exhibit 73 in favour of rationalism. This ideas shows the structure of nature and the workings of our minds. |
| 14410 | You believe you existed last year, but your segment doesn't, so they have different beliefs [Merricks] |
| Full Idea: Your belief that you existed in the year 2000 is true; the belief of a segment of you that it then existed is false; so, by the indiscernibility of identicals, there must be two beliefs here. | |
| From: Trenton Merricks (Truth and Ontology [2007], 6.IV n20) | |
| A reaction: Merricks may be begging the question here. But in the segment view there is nothing which can truly believe it existed a year ago, so therefore nothing here has continued existence, so the segments cannot be part of a single thing. |
| 19214 | In twinning, one person has the same origin as another person [Merricks] |
| Full Idea: Origin essentialists claim that parental union results in a person, and that person could not have resulted from any other union. However, if the fertilised egg undergoes twinning, at least one of the resultant persons is not the original person. | |
| From: Trenton Merricks (Propositions [2015], 5.V) | |
| A reaction: Merricks says that therefore that origin could have just produced the second twin, rather than the original person. This is interesting, but doesn't seem to threaten the necessity of origin thesis. Once I'm here, I have that origin, despite my twin. |
| 6136 | Eliminativism about objects gives the best understanding of the Sorites paradox [Merricks] |
| Full Idea: I say we should endorse eliminativism about physical objects, because it offers the most plausible understanding of what occurs during the Sorites Game (eliminating grains of a thing one at a time). | |
| From: Trenton Merricks (Objects and Persons [2003], §2.II) | |
| A reaction: That is one route to go in explaining the paradox (i.e. by saying there never was a 'heap' in the first place). I suspect a better route is to say that heaps really exist as natural phenomena, but they suffer from vague identity and borderline cases. |
| 14417 | Counterfactuals aren't about actuality, so they lack truthmakers or a supervenience base [Merricks] |
| Full Idea: A counterfactual is not appropriately about the way anything is, …but about how something would be, had other things differed from how they actually are. As a result, true counterfactuals have neither truthmakers nor a superveniece base. | |
| From: Trenton Merricks (Truth and Ontology [2007], 7.IV) | |
| A reaction: Might not the truthmakers for counterfactuals reside in the dispositional facts about actuality? We assess the truth of counterfactuals in degrees, so something must determine our views. |
| 6133 | If my counterpart is happy, that is irrelevant to whether I 'could' have been happy [Merricks] |
| Full Idea: The existence of someone in another world who is a lot like me, but happier, is irrelevant to whether I - this very person - could have been happier, even if we call that other-worldly someone 'my counterpart'. | |
| From: Trenton Merricks (Objects and Persons [2003], §1.IV) | |
| A reaction: He says this is a familiar objection. I retain a lingering deterministic doubt about whether it ever makes to sense to say that I 'could' have been happy, given that I am not. It does seem to make sense to say that I was close to happiness, but missed it. |
| 14402 | If 'Fido is possibly black' depends on Fido's counterparts, then it has no actual truthmaker [Merricks] |
| Full Idea: If Fido's being possibly black reduces (in Lewis's account) to the existence of black counterparts of Fido, then 'Fido is possibly black' is actually true, but it has no actually existing truthmaker. | |
| From: Trenton Merricks (Truth and Ontology [2007], 5.I) | |
| A reaction: This problem is increasingly the target of my views about dispositions and powers. Fido is not possibly a prize-winning novelist, but is possibly dead or in good health, because of the actual nature and dispositions of Fido. |
| 6150 | The 'warrant' for a belief is what turns a true belief into knowledge [Merricks] |
| Full Idea: The 'warrant' for a belief is that, whatever it is, that makes the difference between mere true belief and knowledge. | |
| From: Trenton Merricks (Objects and Persons [2003], §7.II) | |
| A reaction: Hence a false belief could be well justified, but it could never be warranted. This makes warrant something like the externalist view of justification, a good supporting situation for a belief, rather than an inner awareness of support for it. |
| 6144 | You hold a child in your arms, so it is not mental substance, or mental state, or software [Merricks] |
| Full Idea: When you hold your child, you do exactly that - hold the child himself or herself - and not some stand-in. This implies that we are not two substances, and we are not mental states nor akin to software. | |
| From: Trenton Merricks (Objects and Persons [2003], §4) | |
| A reaction: And it is not just a brain, either. This is a nice simple example to support the sensible view that a person is a type of animal. Like all other physical objects that is a bit vague, so we should not be distracted by borderline cases like brain bisection. |
| 6140 | Maybe the word 'I' can only refer to persons [Merricks] |
| Full Idea: One might say that the word 'I' can only have a person as its reference. | |
| From: Trenton Merricks (Objects and Persons [2003], §2.IV) | |
| A reaction: To infer the existence of persons from this would be to commit what I think of as the Linguistic Fallacy, of deducing ontology directly from language. We might allow (Dennett fashion) that folk categories require the fiction of persons. |
| 6149 | Free will and determinism are incompatible, since determinism destroys human choice [Merricks] |
| Full Idea: The main recent support for incompatibilism is the 'no choice' argument: we have no choice that the past and the laws of nature entail human actions, we have no choice about what the past or the laws are like, so we have no choice about our actions. | |
| From: Trenton Merricks (Objects and Persons [2003], §6.III) | |
| A reaction: Since I consider free will to be an absurd chimera, I think this argument involves a total misunderstanding of what a 'choice' is. Since the human brain is a wonderfully sophisticated choosing machine, our whole life consists of choices. |
| 6148 | Human organisms can exercise downward causation [Merricks] |
| Full Idea: Human organisms have non-redundant causal powers, and so can exercise downward causation. | |
| From: Trenton Merricks (Objects and Persons [2003], §4.VII) | |
| A reaction: The hallmark of property dualism. This notion needs a lot more expansion and exploration than Merricks gives it, and I don't think it will be enough to provide 'free will', or even, as Merricks hopes, to place humans in a distinct ontological category. |
| 6147 | The hypothesis of solipsism doesn't seem to be made incoherent by the nature of mental properties [Merricks] |
| Full Idea: The hypothesis of solipsism, that I - an entity with many conscious mental properties - am all that exists, while surely false, is not rendered incoherent simply by the nature of the mental properties. | |
| From: Trenton Merricks (Objects and Persons [2003], §4.II) | |
| A reaction: This, along with the thought of a pre-Creation God, is a nice intuitive case for showing that we strongly believe in some degree of narrow content. |
| 6146 | Before Creation it is assumed that God still had many many mental properties [Merricks] |
| Full Idea: The belief of theists that God might never have created implies that there is a possible world that contains just a single entity with many conscious mental properties. | |
| From: Trenton Merricks (Objects and Persons [2003], §4.II) | |
| A reaction: So if we believe content is wide, we must believe that God was incapable of thought before creation, and thus couldn't plan creation, and so didn't create, and so the Creator is a logical impossibility. Cool. |
| 19217 | I don't accept that if a proposition is directly about an entity, it has a relation to the entity [Merricks] |
| Full Idea: The Aboutness Assumption says that necessarily, if a proposition is directly about an entity, then that proposition stands in a relation to the entity. I shall argue that the Assumption is false. | |
| From: Trenton Merricks (Propositions [2015], 5.VII) | |
| A reaction: This feels sort of right, though the nature of aboutness remains elusive. He cites denials of existence. I take speech to be fairly internal, even though its main role is communication. Maybe its a Cambridge relation, as far as the entity is concerned. |
| 19203 | A sentence's truth conditions depend on context [Merricks] |
| Full Idea: A sentence has truth conditions only in a context of use. And the truth conditions of many sentences can differ from one context of use to another (as in 'I am a philosopher'). | |
| From: Trenton Merricks (Propositions [2015], 1.II) | |
| A reaction: He is building a defence of propositions, because they are eternal, and have their truth conditions essentially. I too am a fan of propositions. |
| 19200 | Propositions are standardly treated as possible worlds, or as structured [Merricks] |
| Full Idea: The thesis that propositions are sets of possible worlds is one of the two leading accounts of the nature of propositions. The other leading account endorses structured propositions. | |
| From: Trenton Merricks (Propositions [2015], Intro) | |
| A reaction: Merricks sets out to reject both main views. I take the idea that propositions actually are sets of possible worlds to be ridiculous (though they may offer a way of modelling them). The idea that they have no structure at all strikes me as odd. |
| 19206 | 'Cicero is an orator' represents the same situation as 'Tully is an orator', so they are one proposition [Merricks] |
| Full Idea: The proposition expressed by 'Cicero is an orator' represents things as being exactly the same way as does the proposition expressed by 'Tully is an orator'. Hence two sentences express the same proposition. Fregeans about names deny this. | |
| From: Trenton Merricks (Propositions [2015], 2.II) | |
| A reaction: Merricks makes the situation in the world fix the contents of the proposition. I don't agree. I would expand the first proposition as 'The person I know as 'Cicero' was an orator', but I might never have heard of 'Tully'. |
| 19202 | Propositions are necessary existents which essentially (but inexplicably) represent things [Merricks] |
| Full Idea: My account says that each proposition is a necessary existent that essentially represents things as being a certain way, ...and there is no explanation of how propositions do that. | |
| From: Trenton Merricks (Propositions [2015], Intro) | |
| A reaction: Since I take propositions to be brain events, I don't expect much of an explanation either. The idea that propositions necessarily exist strikes me as false. If there were no minds, there would have been no propositions. |
| 19204 | True propositions existed prior to their being thought, and might never be thought [Merricks] |
| Full Idea: 1,000 years ago, no sentence had ever expressed, and no one had believed, the true proposition 'a water molecule has two hydrogen and one oxygen atoms'. There are surely true propositions that have never been, and never will be, expressed or believed. | |
| From: Trenton Merricks (Propositions [2015], 1.V) | |
| A reaction: 'Surely'? Surely not! How many propositions exist? Where do they exist? What are they made of? If they already exist when we think them, how do we tune into them? When did his example come into existence? Before water did? No! No! |
| 19210 | The standard view of propositions says they never change their truth-value [Merricks] |
| Full Idea: The standard view among philosophers nowadays seems to be that propositions do not and even cannot change in truth-value. But my own view is that some propositions can, and do, change in truth value. | |
| From: Trenton Merricks (Propositions [2015], 3.VII) | |
| A reaction: He gives 'that A sits' as an example of one which can change, though 'that A sits at time t' cannot change. I take Merricks to be obviously right, and cannot get my head round the 'standard' view. What on earth do they think a proposition is? |
| 19201 | Propositions can be 'about' an entity, but that doesn't make the entity a constituent of it [Merricks] |
| Full Idea: If a singular proposition is 'directly about' an entity, I argue that a singular proposition does not have the entity that it is directly about as a constituent. | |
| From: Trenton Merricks (Propositions [2015], Intro) | |
| A reaction: This opposes the view of the early Russell, that propositions actually contain the entities they are about, thus making propositions real features of the external world. I take that view of Russell's to be absurd. |
| 19211 | Early Russell says a proposition is identical with its truthmaking state of affairs [Merricks] |
| Full Idea: I describe Russell's 1903 account of propositions as the view that each proposition is identical with the state of affairs that makes that proposition true. That is, a proposition is identical with its 'truthmaking' state of affairs. | |
| From: Trenton Merricks (Propositions [2015], 4.II) | |
| A reaction: Russell soon gave this view up (false propositions proving tricky), and I'm amazed anyone takes it seriously. I take it as axiomatic that if there were no minds there would be no propositions. Was the Big Bang a set of propositions? |
| 19212 | Unity of the proposition questions: what unites them? can the same constituents make different ones? [Merricks] |
| Full Idea: What binds the constituents of a structured proposition together into a single unity, a proposition? Can the very same constituents constitute two distinct propositions? These are questions about 'the unity of the proposition'. | |
| From: Trenton Merricks (Propositions [2015], 4.II) | |
| A reaction: Merricks solves it by saying propositions have no structure. The problem is connected to the nature of predication (instantiation, partaking). You can't just list objects and their properties. Objects are united, and thus propositions are too. |
| 19213 | We want to explain not just what unites the constituents, but what unites them into a proposition [Merricks] |
| Full Idea: A successful account of the unity of the proposition tells us what unites the relevant constituents not merely into some entity or other, but into a proposition. | |
| From: Trenton Merricks (Propositions [2015], 4.X) | |
| A reaction: Merrickes takes propositions to be unanalysable unities, but their central activity is representation, so if they needed uniting, that would be the place to look. Some people say that we unite our propositions. Others say the world does. I dunno. |
| 6005 | Animals are dangerous and nourishing, and can't form contracts of justice [Hermarchus, by Sedley] |
| Full Idea: Hermarchus said that animal killing is justified by considerations of human safety and nourishment and by animals' inability to form contractual relations of justice with us. | |
| From: report of Hermarchus (fragments/reports [c.270 BCE]) by David A. Sedley - Hermarchus | |
| A reaction: Could the last argument be used to justify torturing animals? Or could we eat a human who was too brain-damaged to form contracts? |
| 17960 | Eternalism says all times are equally real, and future and past objects and properties are real [Merricks] |
| Full Idea: Eternalism says all times are equally real. Objects existing at past times and objects existing at future times are just as real as objects existing at the present. Properties had at past and future times are as much properties as those at the present. | |
| From: Trenton Merricks (Goodbye Growing Block [2006], 1) | |
| A reaction: He adds that the present is therefore 'subjective', resulting from one's perspective. Why would eternalists reject their subjective experiences of time, unless they reject all their other subjective experiences as well? |
| 17961 | Growing block has a subjective present and a growing edge - but these could come apart [Merricks, by PG] |
| Full Idea: Merricks argues that the growing block view says that we live in the subjective present, and that there is a growing edge of being, but he then suggests that these two could come apart, and it would make no difference, so the growing block is incoherent. | |
| From: report of Trenton Merricks (Goodbye Growing Block [2006], 4) by PG - Db (ideas) | |
| A reaction: [I think that is the nub of his argument. I couldn't find a concise summary in his words] |
| 14411 | Maybe only presentism allows change, by now having a property, and then lacking it [Merricks] |
| Full Idea: Maybe presentism alone allows for genuine change, by permitting the direct having of a property by something and then, later, the absolute lacking of that property by that same thing. | |
| From: Trenton Merricks (Truth and Ontology [2007], 6.IV n23) | |
| A reaction: Four-dimensionalism (perdurantism) is the view which is most often charged with not explaining change, and that tends to be associated with eternalism. Are there just two coherent packages of views here? |
| 14407 | Presentist should deny there is a present time, and just say that things 'exist' [Merricks] |
| Full Idea: I think presentists should deny that there is anything at all that is the present time, just as they should deny that there are past times or future times. They should say that existing at the present time is just 'existing'. | |
| From: Trenton Merricks (Truth and Ontology [2007], 6.I) | |
| A reaction: The whole context is needed to understand Merrick's interesting claim. If there is no present, when can events happen? |
| 14406 | Presentists say that things have existed and will exist, not that they are instantaneous [Merricks] |
| Full Idea: Presentists deny that everything is instantaneous; they think that many objects not only exist, but also have existed and will exist. | |
| From: Trenton Merricks (Truth and Ontology [2007], 6.I) | |
| A reaction: The second half is because presentists are committed to the truth of tensed existence claims (despite a lack of any theory as to how they work). Does anyone hold a theory of Instantaneousism? |
| 14405 | How can a presentist explain an object's having existed? [Merricks] |
| Full Idea: I am not sure what account presentists should give of an object's having existed. | |
| From: Trenton Merricks (Truth and Ontology [2007], 6.I) | |
| A reaction: Personally I am pretty puzzled by the eternalist and growing-block accounts of an object having existed, so we are all up a gum tree here. The best bet is to pull truth and existence apart, but heaven knows what that implies. See Idea 14399. |