109 ideas
| 8558 | One system has properties, powers, events, similarity and substance [Shoemaker] |
| 8559 | Analysis aims at internal relationships, not reduction [Shoemaker] |
| 8594 | People have had good reasons for thinking that the circle has been squared [Shoemaker] |
| 9535 | 'Contradictory' propositions always differ in truth-value [Lemmon] |
| 9509 | That proposition that both P and Q is their 'conjunction', written P∧Q [Lemmon] |
| 9508 | The sign |- may be read as 'therefore' [Lemmon] |
| 9511 | We write the conditional 'if P (antecedent) then Q (consequent)' as P→Q [Lemmon] |
| 9510 | That proposition that either P or Q is their 'disjunction', written P∨Q [Lemmon] |
| 9512 | We write the 'negation' of P (not-P) as ¬ [Lemmon] |
| 9513 | We write 'P if and only if Q' as P↔Q; it is also P iff Q, or (P→Q)∧(Q→P) [Lemmon] |
| 9514 | If A and B are 'interderivable' from one another we may write A -||- B [Lemmon] |
| 9516 | A 'well-formed formula' follows the rules for variables, ¬, →, ∧, ∨, and ↔ [Lemmon] |
| 9517 | The 'scope' of a connective is the connective, the linked formulae, and the brackets [Lemmon] |
| 9519 | A 'substitution-instance' is a wff formed by consistent replacing variables with wffs [Lemmon] |
| 9529 | A wff is 'inconsistent' if all assignments to variables result in the value F [Lemmon] |
| 9531 | 'Contrary' propositions are never both true, so that ¬(A∧B) is a tautology [Lemmon] |
| 9534 | Two propositions are 'equivalent' if they mirror one another's truth-value [Lemmon] |
| 9530 | A wff is 'contingent' if produces at least one T and at least one F [Lemmon] |
| 9532 | 'Subcontrary' propositions are never both false, so that A∨B is a tautology [Lemmon] |
| 9533 | A 'implies' B if B is true whenever A is true (so that A→B is tautologous) [Lemmon] |
| 9528 | A wff is a 'tautology' if all assignments to variables result in the value T [Lemmon] |
| 9518 | A 'theorem' is the conclusion of a provable sequent with zero assumptions [Lemmon] |
| 9396 | DN: Given A, we may derive ¬¬A [Lemmon] |
| 9393 | A: we may assume any proposition at any stage [Lemmon] |
| 9399 | ∧E: Given A∧B, we may derive either A or B separately [Lemmon] |
| 9402 | RAA: If assuming A will prove B∧¬B, then derive ¬A [Lemmon] |
| 9395 | MTT: Given ¬B and A→B, we derive ¬A [Lemmon] |
| 9400 | ∨I: Given either A or B separately, we may derive A∨B [Lemmon] |
| 9401 | ∨E: Derive C from A∨B, if C can be derived both from A and from B [Lemmon] |
| 9398 | ∧I: Given A and B, we may derive A∧B [Lemmon] |
| 9397 | CP: Given a proof of B from A as assumption, we may derive A→B [Lemmon] |
| 9394 | MPP: Given A and A→B, we may derive B [Lemmon] |
| 9521 | 'Modus tollendo ponens' (MTP) says ¬P, P ∨ Q |- Q [Lemmon] |
| 9522 | 'Modus ponendo tollens' (MPT) says P, ¬(P ∧ Q) |- ¬Q [Lemmon] |
| 9525 | We can change conditionals into negated conjunctions with P→Q -||- ¬(P ∧ ¬Q) [Lemmon] |
| 9524 | We can change conditionals into disjunctions with P→Q -||- ¬P ∨ Q [Lemmon] |
| 9523 | De Morgan's Laws make negated conjunctions/disjunctions into non-negated disjunctions/conjunctions [Lemmon] |
| 9527 | The Distributive Laws can rearrange a pair of conjunctions or disjunctions [Lemmon] |
| 9526 | We can change conjunctions into negated conditionals with P→Q -||- ¬(P → ¬Q) [Lemmon] |
| 9537 | Truth-tables are good for showing invalidity [Lemmon] |
| 9538 | A truth-table test is entirely mechanical, but this won't work for more complex logic [Lemmon] |
| 9536 | If any of the nine rules of propositional logic are applied to tautologies, the result is a tautology [Lemmon] |
| 9539 | Propositional logic is complete, since all of its tautologous sequents are derivable [Lemmon] |
| 13909 | Write '(∀x)(...)' to mean 'take any x: then...', and '(∃x)(...)' to mean 'there is an x such that....' [Lemmon] |
| 13902 | 'Gm' says m has property G, and 'Pmn' says m has relation P to n [Lemmon] |
| 13911 | The 'symbols' are bracket, connective, term, variable, predicate letter, reverse-E [Lemmon] |
| 13910 | Our notation uses 'predicate-letters' (for 'properties'), 'variables', 'proper names', 'connectives' and 'quantifiers' [Lemmon] |
| 13904 | Universal Elimination (UE) lets us infer that an object has F, from all things having F [Lemmon] |
| 13906 | With finite named objects, we can generalise with &-Intro, but otherwise we need ∀-Intro [Lemmon] |
| 13908 | UE all-to-one; UI one-to-all; EI arbitrary-to-one; EE proof-to-one [Lemmon] |
| 13901 | Predicate logic uses propositional connectives and variables, plus new introduction and elimination rules [Lemmon] |
| 13903 | Universal elimination if you start with the universal, introduction if you want to end with it [Lemmon] |
| 13905 | If there is a finite domain and all objects have names, complex conjunctions can replace universal quantifiers [Lemmon] |
| 13900 | 'Some Frenchmen are generous' is rendered by (∃x)(Fx→Gx), and not with the conditional → [Lemmon] |
| 9520 | The paradoxes of material implication are P |- Q → P, and ¬P |- P → Q [Lemmon] |
| 15091 | Restrict 'logical truth' to formal logic, rather than including analytic and metaphysical truths [Shoemaker] |
| 8596 | Inability to measure equality doesn't make all lengths unequal [Shoemaker] |
| 8597 | We couldn't verify the earth's rotation if everyone simultaneously fell asleep [Shoemaker] |
| 15092 | Formerly I said properties are individuated by essential causal powers and causing instantiation [Shoemaker, by Shoemaker] |
| 15095 | A property's causal features are essential, and only they fix its identity [Shoemaker] |
| 15097 | I claim that a property has its causal features in all possible worlds [Shoemaker] |
| 8543 | Genuine properties are closely related to genuine changes [Shoemaker] |
| 8551 | Properties must be essentially causal if we can know and speak about them [Shoemaker] |
| 8557 | To ascertain genuine properties, examine the object directly [Shoemaker] |
| 15761 | We should abandon the idea that properties are the meanings of predicate expressions [Shoemaker] |
| 15756 | Some truths are not because of a thing's properties, but because of the properties of related things [Shoemaker] |
| 15758 | Things have powers in virtue of (which are entailed by) their properties [Shoemaker] |
| 8547 | One power can come from different properties; a thing's powers come from its properties [Shoemaker] |
| 8549 | Properties are functions producing powers, and powers are functions producing effects [Shoemaker] |
| 15094 | I now deny that properties are cluster of powers, and take causal properties as basic [Shoemaker] |
| 12678 | Shoemaker says all genuine properties are dispositional [Shoemaker, by Ellis] |
| 8545 | A causal theory of properties focuses on change, not (say) on abstract properties of numbers [Shoemaker] |
| 15757 | 'Square', 'round' and 'made of copper' show that not all properties are dispositional [Shoemaker] |
| 15759 | The identity of a property concerns its causal powers [Shoemaker] |
| 15760 | Properties are clusters of conditional powers [Shoemaker] |
| 15762 | Could properties change without the powers changing, or powers change without the properties changing? [Shoemaker] |
| 8552 | If properties are separated from causal powers, this invites total elimination [Shoemaker] |
| 4040 | The notions of property and of causal power are parts of a single system of related concepts [Shoemaker] |
| 15765 | Actually, properties are individuated by causes as well as effects [Shoemaker] |
| 14534 | Shoemaker moved from properties as powers to properties bestowing powers [Shoemaker, by Mumford/Anjum] |
| 8548 | Dispositional predicates ascribe powers, and the rest ascribe properties [Shoemaker] |
| 9485 | Universals concern how things are, and how they could be [Shoemaker, by Bird] |
| 8550 | Triangular and trilateral are coextensive, but different concepts; but powers and properties are the same [Shoemaker] |
| 8555 | There is no subset of properties which guarantee a thing's identity [Shoemaker] |
| 15099 | If something is possible, but not nomologically possible, we need metaphysical possibility [Shoemaker] |
| 8554 | Possible difference across worlds depends on difference across time in the actual world [Shoemaker] |
| 15101 | Once you give up necessity as a priori, causal necessity becomes the main type of necessity [Shoemaker] |
| 15764 | 'Conceivable' is either not-provably-false, or compatible with what we know? [Shoemaker] |
| 15098 | Empirical evidence shows that imagining a phenomenon can show it is possible [Shoemaker] |
| 15100 | Imagination reveals conceptual possibility, where descriptions avoid contradiction or incoherence [Shoemaker] |
| 8562 | It is possible to conceive what is not possible [Shoemaker] |
| 5691 | The adverbial account of sensation says not 'see a red image' but be 'appeared to redly' [Shoemaker] |
| 8593 | Maybe billions of changeless years have elapsed since my last meal [Shoemaker] |
| 7295 | Maybe induction is only reliable IF reality is stable [Mitchell,A] |
| 15096 | 'Grue' only has causal features because of its relation to green [Shoemaker] |
| 8556 | Grueness is not, unlike green and blue, associated with causal potential [Shoemaker] |
| 5687 | For true introspection, must we be aware that we are aware of our mental events? [Shoemaker] |
| 5688 | Empirical foundationalism says basic knowledge is self-intimating, and incorrigible or infallible [Shoemaker] |
| 1389 | If memory is the sole criterion of identity, we ought to use it for other people too [Shoemaker] |
| 1390 | Bodily identity is one criterion and memory another, for personal identity [Shoemaker, by PG] |
| 8542 | If causality is between events, there must be reference to the properties involved [Shoemaker] |
| 8598 | If things turn red for an hour and then explode, we wouldn't say the redness was the cause [Shoemaker] |
| 15093 | We might say laws are necessary by combining causal properties with Armstrong-Dretske-Tooley laws [Shoemaker] |
| 8560 | If causal laws describe causal potentialities, the same laws govern properties in all possible worlds [Shoemaker] |
| 15763 | If properties are causal, then causal necessity is a species of logical necessity [Shoemaker] |
| 8561 | If a world has different causal laws, it must have different properties [Shoemaker] |
| 8553 | It looks as if the immutability of the powers of a property imply essentiality [Shoemaker] |
| 4226 | If three regions 'freeze' every three, four and five years, after sixty years everything stops for a year [Shoemaker, by Lowe] |
| 8595 | If three regions freeze every 3rd, 4th and 5th year, they all freeze together every 60 years [Shoemaker] |