92 ideas
| 7910 | Pursue truth with the urgency of someone whose clothes are on fire [Ashvaghosha] |
| Full Idea: As though your turban or your clothes were on fire, so with a sense of urgency should you apply your intellect to the comprehension of the truths. | |
| From: Ashvaghosha (Saundaranandakavya [c.50], XVI) | |
| A reaction: The best philosophers need no such urging. I retain a romantic view that we should be 'natural' in these things. See Plato's views in Idea 2153 and 1638. However, maybe I should be confronted with this quotation every morning when I awake. |
| 4588 | There is no such thing as 'science'; there are just many different sciences [Heil] |
| Full Idea: There is no such thing as science; there are only sciences: physics, chemistry, meteorology, geology, biology, psychology, sociology. | |
| From: John Heil (Philosophy of Mind [1998], Intro) | |
| A reaction: A simple but nice point. It suggests that maybe each science has an entirely different method, and style of reasoning, experiment and explanation. Some have strict laws, others have 'ceteris paribus' laws. |
| 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. |
| 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. |
| 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) |
| 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) |
| 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). |
| 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) |
| 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) |
| 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) |
| 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) |
| 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) |
| 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) |
| 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) |
| 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'. |
| 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) |
| 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) |
| 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) |
| 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) |
| 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) |
| 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) |
| 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) |
| 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) |
| 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) |
| 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. |
| 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) |
| 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) |
| 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) |
| 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) |
| 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) |
| 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] |
| 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] |
| 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) |
| 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) |
| 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. |
| 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. |
| 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. |
| 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. |
| 4616 | A higher level is 'supervenient' if it is determined by lower levels, but has its own natural laws [Heil] |
| Full Idea: 'Supervenience' means lower-level objects and properties suffice for the higher level ones, but the higher level is distinct from its ground, which is reflected in the higher level being governed by distinct laws of nature. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: A nice summary of Davidson's idea. It feels wrong to me. Can I create some 'new laws of nature' by combining things novelly in a laboratory so that a supervenient state emerges. Sounds silly to me. Must we invoke God to achieve this? |
| 4603 | Functionalists in Fodor's camp usually say that a genuine property is one that figures in some causal laws [Heil] |
| Full Idea: Functionalists in Fodor's camp usually say that a genuine property is one that figures in some causal laws. | |
| From: John Heil (Philosophy of Mind [1998], Ch.4) | |
| A reaction: The problem is that anything which can't figure in a causal law will therefore be undetectable, so we could only speculate about the existence of such properties, never know them. |
| 4617 | A stone does not possess the property of being a stone; its other properties make it a stone [Heil] |
| Full Idea: A predicate that does not designate a property could nevertheless hold true of an object in virtue of that object's properties. An object is a stone not in virtue of holding the property of being a stone, but because it possesses certain other properties. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: Sounds simple but important, especially in relation to the mind. We are left with the problem of how to individuate a property, and the possibility of 'basic' properties. |
| 4615 | Complex properties are not new properties, they are merely new combinations of properties [Heil] |
| Full Idea: New combinations of properties are just that: new combinations, not new properties. (This is not to reject complex properties, but only to reaffirm that complex properties are nothing over and above their constituents suitably arranged). | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: I wish I could be so confidence, but no one seems quite sure what a property is. Are they defined causally, or as 'qualities'? If the latter, what is a quality? Are there basic properties? Can properties merge to form a new one? |
| 4612 | Complex properties are just arrangements of simple properties; they do not "emerge" as separate [Heil] |
| Full Idea: Complex properties do not "emerge"; they are nothing "over and above" the properties of the simple constituents duly arranged. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: I am glad to see someone challenging the concept of 'emergence', which strikes me as incoherent. Small properties add up to macro-properties (like 'steep', or 'square'). |
| 4587 | From the property predicates P and Q, we can get 'P or Q', but it doesn't have to designate another property [Heil] |
| Full Idea: If P and Q are predicates denoting properties, we can construct a disjunctive predicate ('P or Q'). But it is not clear that this gives us any right whatever to suppose that 'P or Q' designates a property. | |
| From: John Heil (Philosophy of Mind [1998], Pref) | |
| A reaction: An important idea, needed to disentangle our ontology from our language, and realise that they are separate. Properties are natural; predicates are conventional. |
| 4611 | The supporters of 'tropes' treat objects as bundles of tropes, when I think objects 'possess' properties [Heil] |
| Full Idea: I resist the term 'trope' as it has become common for the proponents of tropes to regard objects as "bundles" of tropes. This turns tropes into something too much resembling parts of objects for my taste. .I think an object is a possessor of properties. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: This seems to imply a belief in 'substance', which is an intrinsically dodgy concept, but something has to exist. Keep ontology and epistemology separate! We can only know bundles of properties. |
| 4592 | If you can have the boat without its current planks, and the planks with no boat, the planks aren't the boat [Heil] |
| Full Idea: If a boat can continue to exist after the planks that currently make it up have ceased to exist, and if the planks could continue to exist when the boat does not, then a boat cannot be identified with the planks that make it up at a given time. | |
| From: John Heil (Philosophy of Mind [1998], Ch.2) | |
| A reaction: This seems obvious, but it opposes Locke's claim that the particles of an object are its identity. Does this mean identities are entirely in our heads, and not a feature of nature? I want to resist that. |
| 4586 | You can't embrace the formal apparatus of possible worlds, but reject the ontology [Heil] |
| Full Idea: We should be suspicious of anyone who embraces the formal apparatus of possible worlds while rejecting the ontology. | |
| From: John Heil (Philosophy of Mind [1998], Pref) | |
| A reaction: What matters is that good philosophy should not duck the ontological implications of any apparatus. If only embracing the 'ontology of possible worlds' were a simple matter. What makes one world 'close' to another? |
| 4591 | Idealism explains appearances by identifying appearances with reality [Heil] |
| Full Idea: Idealism explains appearances by identifying appearances with reality. | |
| From: John Heil (Philosophy of Mind [1998], Ch.2) | |
| A reaction: Nicely put. There is a certain intellectual integrity about idealism, but it is still mad. The overall picture seems to me incoherent if we don't assume that appearances are bringing us close to reality (without ever quite getting there). |
| 4610 | Different generations focus on either the quality of mind, or its scientific standing, or the content of thought [Heil] |
| Full Idea: One generation addresses the qualitative aspect of mentality, the next focuses on its scientific standing, its successor takes up the problem of mental content, then the cycle starts all over again… | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: This pinpoints the three interlinked questions. We seem to be currently obsessed with the quality of experience (the 'Hard Question'), but the biggest questions is how the three aspects fit together. If there are three necessities here, they must coexist. |
| 4618 | If minds are realised materially, it looks as if the material laws will pre-empt any causal role for mind [Heil] |
| Full Idea: If a mental property is realised by a material property, then it looks as though its material realiser pre-empts any causal contribution on the part of the realised mental property. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: This has a beautiful simplicity about it. I can see how some very odd phenomena might suddenly appear out of a physical combination, but not how entirely new causal laws can be created. |
| 4621 | Whatever exists has qualities, so it is no surprise that states of minds have qualities [Heil] |
| Full Idea: Whatever exists has qualities, so it is no surprise that states of minds have qualities. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: If only I knew what a 'quality' was. Do combinations have qualities in addition to the qualities of the components? A pair of trees, a pile of sand, a mass of neurons. |
| 4623 | Propositional attitudes are not the only intentional states; there is also mental imagery [Heil] |
| Full Idea: Some philosophers have thought that intentional states are exhausted by propositional attitudes, but what about mental imagery? You may have propositional attitudes to food, but I would wager that most of your thoughts about it are imagistic. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: Seems right. If I encounter an object by which I am bewildered, I may form no propositions at all about it, but I can still contemplate the object. |
| 4626 | The widespread externalist view says intentionality has content because of causal links of agent to world [Heil] |
| Full Idea: The prevailing 'externalist' line on intentionality regards intentional states of mind as owing their content (what they are of, or about) to causal relations agents bear to the world. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: This goes back to Putnam's Twin Earth. 'Meanings aren't in the head'. I may defer to experts about what 'elm' means, but I may also be arrogantly wrong about what 'juniper' means. |
| 4622 | Error must be possible in introspection, because error is possible in all judgements [Heil] |
| Full Idea: Error, like truth, presupposes judgement. Judgements you make about your conscious states are distinct from those states. This leaves room for error. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: This sounds very neat. The reply would have to be that a lot of introspection is not judgement, but direct perception of self-evident facts and truths. I agree with Heil. |
| 4590 | If causation is just regularities in events, the interaction of mind and body is not a special problem [Heil] |
| Full Idea: If causal relations boil down to nothing more than regularities (as Hume suggests), then it is a mistake to regard the absence of a mechanism or causal link between mental events and material events as a special problem. | |
| From: John Heil (Philosophy of Mind [1998], Ch.2) | |
| A reaction: So critics of Descartes who were baffled by interaction, were actually sniffing Hume's wholesale scepticism about necessary causation. Even so, physical conjunction is more tangible than spiritual conjunction. |
| 4614 | Disposition is a fundamental feature of reality, since basic particles are capable of endless possible interactions [Heil] |
| Full Idea: If there are elementary particles, then they are certainly capable of endless interactions beyond those in which they actually engage. Everything points to dispositionality being a fundamental feature of our world. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: I'm not convinced that my ontology has to include something called a 'disposition'. Dispositions are the consequence of how things are. Are there passive dispositions? |
| 4595 | No mental state entails inevitable behaviour, because other beliefs or desires may intervene [Heil] |
| Full Idea: Any attempt to say what behaviour follows from a given state of mind can be shown to be false by producing an example in which the state of mind is present but, owing to the addition of new beliefs and desires, the behaviour does not follow. | |
| From: John Heil (Philosophy of Mind [1998], Ch.3) | |
| A reaction: The objection seems misplaced against eliminative behaviourism, because there are held to be no mental states to correlate with the behavior. There is just behaviour, some times the same, sometimes different. |
| 4599 | Hearts are material, but functionalism says the property of being a heart is not a material property [Heil] |
| Full Idea: Although your heart is a material object, the property of being a heart is, if we accept the functionalist picture, not a material property. | |
| From: John Heil (Philosophy of Mind [1998], Ch.4) | |
| A reaction: Presumably functional properties are not physical because they are multiply realisable. The property of being a heart is more like a theoretical flow diagram than it is like a muscle. That word 'property' again… |
| 4624 | If you are a functionalist, there appears to be no room for qualia [Heil] |
| Full Idea: If you are a functionalist, there appears to be no room for qualia. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: The problem is not that qualia must be denied, but that there is strong pressure to class them as epiphenomena. However, a raw colour can have a causal role (e.g. in an art gallery). Best to say (with Chalmers?) that functions cause qualia? |
| 4601 | Higher-level sciences cannot be reduced, because their concepts mark boundaries invisible at lower levels [Heil] |
| Full Idea: The categories definitive of a given science mark off boundaries that are largely invisible within science at lower levels. That is why there is, in general, no prospect of reducing a higher-level science to a science at some lower level. | |
| From: John Heil (Philosophy of Mind [1998], Ch.4) | |
| A reaction: This sounds slick, but I am unconvinced. Molecules only exist at the level of chemistry, but they are built up out of physics, and the 'boundaries' could be explained in physics, if you had the knowledge and patience. |
| 4602 | Higher-level sciences designate real properties of objects, which are not reducible to lower levels [Heil] |
| Full Idea: The categories embedded in a higher-level science (psychology, for instance) designate genuine properties of objects, which are not reducible to properties found in sciences at lower levels. | |
| From: John Heil (Philosophy of Mind [1998], Ch.4) | |
| A reaction: This isn't an argument against reductionism. It is obviously true that someone with a physics degree won't make a good doctor. It's these wretched 'property' things again. Is 'found repulsive by me' a property terrorists? |
| 4593 | 'Property dualism' says mind and body are not substances, but distinct families of properties [Heil] |
| Full Idea: 'Property dualism' is the view according to which the mental and the physical are not distinguishable kinds of substance, but distinct families of properties. | |
| From: John Heil (Philosophy of Mind [1998], Ch.2 n) | |
| A reaction: I am struggling to make sense of properties being in distinct families. If it is like smells and colours, it doesn't say much, and if the difference is more profound then it begins to look like old-fashioned dualism in disguise. |
| 4597 | Early identity theory talked of mind and brain 'processes', but now the focus is properties [Heil] |
| Full Idea: The early identity theorists talked of identifying mental processes with brain processes, but I am now proposing it as a theory about properties. | |
| From: John Heil (Philosophy of Mind [1998], Ch.3) | |
| A reaction: Since a process is presumably composed of more basic ontological ingredients, this is presumably a good move, but there is still a vagueness about the whole concept of a 'property'. |
| 4609 | It seems contradictory to be asked to believe that we can be eliminativist about beliefs [Heil] |
| Full Idea: Some have argued that eliminativism about propositional attitudes is self-refuting. If no one believes anything, then how could we believe the eliminativist thesis? | |
| From: John Heil (Philosophy of Mind [1998], Ch.5) | |
| A reaction: Sounds slick, but it doesn't strike me as a big problem. Presumably you don't 'believe' eliminativism. You treat some of your brain processes as if they fell into the fictional category of 'belief'. |
| 4596 | The appeal of the identity theory is its simplicity, and its solution to the mental causation problem [Heil] |
| Full Idea: The identity theory is preferable to dualism since 1) if mental events are neurological, it is easy to explain causal relations between them, and 2) if we can account for mental phenomena by reference to brains and their properties, we don't need minds. | |
| From: John Heil (Philosophy of Mind [1998], Ch.3) | |
| A reaction: One might add that it fits into the overall scientific world, and permits the possible closure of physics. The challenge is that identity theory must 'save the phenomena'. |
| 4598 | Functionalists emphasise that mental processes are not to be reduced to what realises them [Heil] |
| Full Idea: The functionalists' point is that higher-level properties like being in pain or computing the sum of 7 and 5 are not to be identified with ("reduced to") or mistaken for their realisers. | |
| From: John Heil (Philosophy of Mind [1998], Ch.4) | |
| A reaction: I take it that functionalist minds can't be reduced because they are abstractions rather than physical entities. Nevertheless, the implied ontology seems to be entirely physical, and hence in some sense reductionist. |
| 4619 | 'Multiple realisability' needs to clearly distinguish low-level realisers from what is realised [Heil] |
| Full Idea: Proponents of multiple realisability regard it as vital to distinguish realised, higher-level properties from their lower-level realisers. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: So that the very idea of 'multiple realisability' begs the question. Minds are private, so it is never clear what has been realised, especially in non-linguistic brains. |
| 4620 | Multiple realisability is not a relation among properties, but an application of predicates to resembling things [Heil] |
| Full Idea: Multiple realisability is not a relation among properties; it is the phenomenon of predicates applying to objects in virtue of distinct, though pertinently similar, properties possessed by those objects. | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: The analogies for multiple realisability usually involve functions rather than properties or predicates (different types of corkscrew). Pain or belief in danger are not just 'predicates'. |
| 4594 | A scientist could know everything about the physiology of headaches, but never have had one [Heil] |
| Full Idea: Imagine a neuroscientist who is intimately familiar with the physiology of headaches, but who has never actually experienced a headache. | |
| From: John Heil (Philosophy of Mind [1998], Ch.3) | |
| A reaction: A more realistic version of Frank Jackson's 'Mary'. Doctors need to know that headaches are unpleasant; what they actually feel like seems irrelevant (epiphenomenal). What's it like to only have two pairs of shoes? |
| 4625 | Is mental imagery pictorial, or is it propositional? [Heil] |
| Full Idea: A fierce debate has raged between proponents of 'pictorial' conceptions of imagery (Kosslyn) and those who take imagery to be propositional (Pylyshyn). | |
| From: John Heil (Philosophy of Mind [1998], Ch.6) | |
| A reaction: This may not be a simple dilemma. Pure pictorial imagery seem possible (abstract patterns) and pure propositions are okay (maths), but in most thought they are inextricable. The image is the proposition (a nuclear cloud). |
| 4607 | Folk psychology and neuroscience are no more competitors than cartography and geology are [Heil] |
| Full Idea: Folk psychology and neuroscience are not competitors, any more than cartography and geology are competitors. | |
| From: John Heil (Philosophy of Mind [1998], Ch.5) | |
| A reaction: This seems true enough, unless someone like Fodor claims that the correct way to do neuroscience is to try to explicate folk psychology categories in terms of brain function. Folk psychology is fine for folk. |
| 4605 | Truth-conditions correspond to the idea of 'literal meaning' [Heil] |
| Full Idea: I intend the notion of truth-conditions to correspond to what I have called 'literal meaning'. | |
| From: John Heil (Philosophy of Mind [1998], Ch.5) | |
| A reaction: Yes. If I identify myself to you by saying "the spam is in the fridge", that always has a literal meaning (which we assemble from the words), as well as connotation in this particular context. |
| 4606 | To understand 'birds warble' and 'tigers growl', you must also understand 'tigers warble' [Heil] |
| Full Idea: There is something puzzling about the notion that someone could understand the sentences "birds warble" and "tigers growl", yet have no idea what the sentence "tigers warble" meant. | |
| From: John Heil (Philosophy of Mind [1998], Ch.5) | |
| A reaction: True enough, but this need not imply the full thesis of linguistic holism. Words are assembled like bricks. I know tigers might warble, but stones don't. Might fish warble? Or volcanoes? I must know that 'birds warble' is not a tautology. |
| 4604 | If propositions are abstract entities, how do human beings interact with them? [Heil] |
| Full Idea: Anyone who takes propositions to be abstract entities owes the rest of us an account of how human beings could interact with such things. | |
| From: John Heil (Philosophy of Mind [1998], Ch.5) | |
| A reaction: He makes this sound impossible, but that would mean that all abstraction is impossible, and there are no such things as ideas and concepts. In the end something has to be miraculous, so let it be our ability to think about abstractions. |
| 7909 | The Eightfold Path concerns morality, wisdom, and tranquillity [Ashvaghosha] |
| Full Idea: The Eightfold Path has three steps concerning morality - right speech, right bodily action, and right livelihood; three of wisdom - right views, right intentions, and right effort; and two of tranquillity - right mindfulness and right concentration. | |
| From: Ashvaghosha (Saundaranandakavya [c.50], XVI) | |
| A reaction: Most of this translates quite comfortably into the aspirations of western philosophy. For example, 'right effort' sounds like Kant's claim that only a good will is truly good (Idea 3710). The Buddhist division is interesting for action theory. |
| 7908 | At the end of a saint, he is not located in space, but just ceases to be disturbed [Ashvaghosha] |
| Full Idea: When an accomplished saint comes to the end, he does not go anywhere down in the earth or up in the sky, nor into any of the directions of space, but because his defilements have become extinct he simply ceases to be disturbed. | |
| From: Ashvaghosha (Saundaranandakavya [c.50], XVI) | |
| A reaction: To 'cease to be disturbed' is the most attractive account of heaven I have encountered. It all sounds a bit dull though. I wonder, as usual, how they know all this stuff. |