80 ideas
| 10468 | A metaphysics has an ontology (objects) and an ideology (expressed ideas about them) [Oliver] |
| 10471 | Ockham's Razor has more content if it says believe only in what is causal [Oliver] |
| 10749 | Necessary truths seem to all have the same truth-maker [Oliver] |
| 10750 | Slingshot Argument: seems to prove that all sentences have the same truth-maker [Oliver] |
| 13634 | Satisfaction is 'truth in a model', which is a model of 'truth' [Shapiro] |
| 13643 | Aristotelian logic is complete [Shapiro] |
| 13651 | A set is 'transitive' if contains every member of each of its members [Shapiro] |
| 13647 | Choice is essential for proving downward Löwenheim-Skolem [Shapiro] |
| 13631 | Are sets part of logic, or part of mathematics? [Shapiro] |
| 13640 | Russell's paradox shows that there are classes which are not iterative sets [Shapiro] |
| 13654 | It is central to the iterative conception that membership is well-founded, with no infinite descending chains [Shapiro] |
| 13666 | Iterative sets are not Boolean; the complement of an iterative set is not an iterative sets [Shapiro] |
| 13653 | 'Well-ordering' of a set is an irreflexive, transitive, and binary relation with a least element [Shapiro] |
| 13642 | Logic is the ideal for learning new propositions on the basis of others [Shapiro] |
| 13627 | There is no 'correct' logic for natural languages [Shapiro] |
| 13667 | Skolem and Gödel championed first-order, and Zermelo, Hilbert, and Bernays championed higher-order [Shapiro] |
| 13668 | Bernays (1918) formulated and proved the completeness of propositional logic [Shapiro] |
| 13669 | Can one develop set theory first, then derive numbers, or are numbers more basic? [Shapiro] |
| 13662 | First-order logic was an afterthought in the development of modern logic [Shapiro] |
| 13624 | The 'triumph' of first-order logic may be related to logicism and the Hilbert programme, which failed [Shapiro] |
| 13660 | Maybe compactness, semantic effectiveness, and the Löwenheim-Skolem properties are desirable [Shapiro] |
| 13673 | The notion of finitude is actually built into first-order languages [Shapiro] |
| 15944 | Second-order logic is better than set theory, since it only adds relations and operations, and nothing else [Shapiro, by Lavine] |
| 13629 | Broad standard semantics, or Henkin semantics with a subclass, or many-sorted first-order semantics? [Shapiro] |
| 13650 | Henkin semantics has separate variables ranging over the relations and over the functions [Shapiro] |
| 13645 | In standard semantics for second-order logic, a single domain fixes the ranges for the variables [Shapiro] |
| 13649 | Completeness, Compactness and Löwenheim-Skolem fail in second-order standard semantics [Shapiro] |
| 13637 | If a logic is incomplete, its semantic consequence relation is not effective [Shapiro] |
| 13626 | Semantic consequence is ineffective in second-order logic [Shapiro] |
| 13632 | Finding the logical form of a sentence is difficult, and there are no criteria of correctness [Shapiro] |
| 13674 | We might reduce ontology by using truth of sentences and terms, instead of using objects satisfying models [Shapiro] |
| 13633 | 'Satisfaction' is a function from models, assignments, and formulas to {true,false} [Shapiro] |
| 13644 | Semantics for models uses set-theory [Shapiro] |
| 13636 | An axiomatization is 'categorical' if its models are isomorphic, so there is really only one interpretation [Shapiro] |
| 13670 | Categoricity can't be reached in a first-order language [Shapiro] |
| 13658 | Downward Löwenheim-Skolem: each satisfiable countable set always has countable models [Shapiro] |
| 13659 | Upward Löwenheim-Skolem: each infinite model has infinite models of all sizes [Shapiro] |
| 13648 | The Löwenheim-Skolem theorems show an explosion of infinite models, so 1st-order is useless for infinity [Shapiro] |
| 13675 | Substitutional semantics only has countably many terms, so Upward Löwenheim-Skolem trivially fails [Shapiro] |
| 13635 | 'Weakly sound' if every theorem is a logical truth; 'sound' if every deduction is a semantic consequence [Shapiro] |
| 13628 | We can live well without completeness in logic [Shapiro] |
| 13630 | Non-compactness is a strength of second-order logic, enabling characterisation of infinite structures [Shapiro] |
| 13646 | Compactness is derived from soundness and completeness [Shapiro] |
| 13661 | A language is 'semantically effective' if its logical truths are recursively enumerable [Shapiro] |
| 13641 | Complex numbers can be defined as reals, which are defined as rationals, then integers, then naturals [Shapiro] |
| 13676 | Only higher-order languages can specify that 0,1,2,... are all the natural numbers that there are [Shapiro] |
| 13677 | Natural numbers are the finite ordinals, and integers are equivalence classes of pairs of finite ordinals [Shapiro] |
| 13652 | The 'continuum' is the cardinality of the powerset of a denumerably infinite set [Shapiro] |
| 13657 | First-order arithmetic can't even represent basic number theory [Shapiro] |
| 13656 | Some sets of natural numbers are definable in set-theory but not in arithmetic [Shapiro] |
| 13664 | Logicism is distinctive in seeking a universal language, and denying that logic is a series of abstractions [Shapiro] |
| 13625 | Mathematics and logic have no border, and logic must involve mathematics and its ontology [Shapiro] |
| 13663 | Some reject formal properties if they are not defined, or defined impredicatively [Shapiro] |
| 10747 | Accepting properties by ontological commitment tells you very little about them [Oliver] |
| 10748 | Reference is not the only way for a predicate to have ontological commitment [Oliver] |
| 10721 | If properties are sui generis, are they abstract or concrete? [Oliver] |
| 10719 | There are four conditions defining the relations between particulars and properties [Oliver] |
| 10716 | There are just as many properties as the laws require [Oliver] |
| 10720 | We have four options, depending whether particulars and properties are sui generis or constructions [Oliver] |
| 10714 | The expressions with properties as their meanings are predicates and abstract singular terms [Oliver] |
| 10715 | There are five main semantic theories for properties [Oliver] |
| 13638 | Properties are often seen as intensional; equiangular and equilateral are different, despite identity of objects [Shapiro] |
| 10739 | The property of redness is the maximal set of the tropes of exactly similar redness [Oliver] |
| 10738 | Tropes are not properties, since they can't be instantiated twice [Oliver] |
| 10740 | The orthodox view does not allow for uninstantiated tropes [Oliver] |
| 10741 | Maybe concrete particulars are mereological wholes of abstract particulars [Oliver] |
| 10742 | Tropes can overlap, and shouldn't be splittable into parts [Oliver] |
| 10472 | 'Structural universals' methane and butane are made of the same universals, carbon and hydrogen [Oliver] |
| 10724 | Located universals are wholly present in many places, and two can be in the same place [Oliver] |
| 10730 | If universals ground similarities, what about uniquely instantiated universals? [Oliver] |
| 7963 | Aristotle's instantiated universals cannot account for properties of abstract objects [Oliver] |
| 7962 | Uninstantiated properties are useful in philosophy [Oliver] |
| 10727 | Uninstantiated universals seem to exist if they themselves have properties [Oliver] |
| 10722 | Instantiation is set-membership [Oliver] |
| 10744 | Nominalism can reject abstractions, or universals, or sets [Oliver] |
| 10726 | Things can't be fusions of universals, because two things could then be one thing [Oliver] |
| 10725 | Abstract sets of universals can't be bundled to make concrete things [Oliver] |
| 10745 | Science is modally committed, to disposition, causation and law [Oliver] |
| 10746 | Conceptual priority is barely intelligible [Oliver] |
| 468 | Musical performance can reveal a range of virtues [Damon of Ath.] |