104 ideas
| 18559 | Philosophy is empty if it does not in some way depend on matters of fact [Machery] |
| 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] |
| 13654 | It is central to the iterative conception that membership is well-founded, with no infinite descending chains [Shapiro] |
| 13640 | Russell's paradox shows that there are classes which are not iterative sets [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] |
| 13627 | There is no 'correct' logic for natural languages [Shapiro] |
| 13642 | Logic is the ideal for learning new propositions on the basis of others [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] |
| 13667 | Skolem and Gödel championed first-order, and Zermelo, Hilbert, and Bernays championed higher-order [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] |
| 13626 | Semantic consequence is ineffective in second-order logic [Shapiro] |
| 13637 | If a logic is incomplete, its semantic consequence relation is not effective [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] |
| 18564 | Do categories store causal knowledge, or typical properties, or knowledge of individuals? [Machery] |
| 18604 | Are quick and slow categorisation the same process, or quite different? [Machery] |
| 18573 | For each category of objects (such as 'dog') an individual seems to have several concepts [Machery] |
| 18602 | A thing is classified if its features are likely to be generated by that category's causal laws [Machery] |
| 18565 | There may be ad hoc categories, such as the things to pack in your suitcase for a trip [Machery] |
| 13638 | Properties are often seen as intensional; equiangular and equilateral are different, despite identity of objects [Shapiro] |
| 18570 | There may be several ways to individuate things like concepts [Machery] |
| 18616 | If a term doesn't pick out a kind, keeping it may block improvements in classification [Machery] |
| 18614 | Vertical arguments say eliminate a term if it picks out different natural kinds in different theories [Machery] |
| 18615 | Horizontal arguments say eliminate a term if it fails to pick out a natural kind [Machery] |
| 18609 | Psychologists use 'induction' as generalising a property from one category to another [Machery] |
| 18610 | 'Ampliative' induction infers that all members of a category have a feature found in some of them [Machery] |
| 18562 | Connectionists cannot distinguish concept-memories from their background, or the processes [Machery] |
| 18561 | We can identify a set of cognitive capacities which are 'higher order' [Machery] |
| 18574 | Concepts for categorisation and for induction may be quite different [Machery] |
| 18588 | Concept theories aim at their knowledge, processes, format, acquisition, and location [Machery] |
| 18611 | We should abandon 'concept', and just use 'prototype', 'exemplar' and 'theory' [Machery] |
| 18567 | In the philosophy of psychology, concepts are usually introduced as constituents of thoughts [Machery] |
| 18569 | In philosophy theories of concepts explain how our propositional attitudes have content [Machery] |
| 18563 | By 'concept' psychologists mean various sorts of representation or structure [Machery] |
| 18558 | Concept theorists examine their knowledge, format, processes, acquisition and location [Machery] |
| 18557 | Psychologists treat concepts as long-term knowledge bodies which lead to judgements [Machery] |
| 18560 | Psychologist treat concepts as categories [Machery] |
| 18592 | The concepts OBJECT or AGENT may be innate [Machery] |
| 18566 | Concepts should contain working memory, not long-term, because they control behaviour [Machery] |
| 18584 | One hybrid theory combines a core definition with a prototype for identification [Machery] |
| 18585 | Heterogeneous concepts might have conflicting judgements, where hybrid theories will not [Machery] |
| 18578 | Concepts as definitions was rejected, and concepts as prototypes, exemplars or theories proposed [Machery] |
| 18575 | The concepts for a class typically include prototypes, and exemplars, and theories [Machery] |
| 18591 | Classical theory can't explain facts like typical examples being categorised quicker [Machery] |
| 18583 | Many categories don't seem to have a definition [Machery] |
| 18590 | Classical theory implies variety in processing times, but this does not generally occur [Machery] |
| 18594 | Knowing typical properties of things is especially useful in induction [Machery] |
| 18593 | The term 'prototype' is used for both typical category members, and the representation [Machery] |
| 18595 | Prototype theories are based on computation of similarities with the prototype [Machery] |
| 18596 | Prototype theorists don't tell us how we select the appropriate prototype [Machery] |
| 18603 | Maybe concepts are not the typical properties, but the ideal properties [Machery] |
| 18605 | It is more efficient to remember the prototype, than repeatedly create it from exemplars [Machery] |
| 18606 | The prototype view predicts that typical members are easier to categorise [Machery] |
| 18597 | Concepts as exemplars are based on the knowledge of properties of each particular [Machery] |
| 18598 | Exemplar theories need to explain how the relevant properties are selected from a multitude of them [Machery] |
| 18599 | In practice, known examples take priority over the rest of the set of exemplars [Machery] |
| 18600 | Theory Theory says category concepts are knowledge stores explaining membership [Machery] |
| 18601 | Theory Theory says concepts are explanatory knowledge, and concepts form domains [Machery] |
| 18607 | Theory theorists rely on best explanation, rather than on similarities [Machery] |
| 18608 | If categorisation is not by similarity, it seems to rely on what properties things might have [Machery] |
| 18587 | The theory account is sometimes labelled as 'knowledge' or 'explanation' in approach [Machery] |
| 18577 | The word 'grandmother' may be two concepts, with a prototype and a definition [Machery] |
| 18589 | For behaviourists concepts are dispositions to link category members to names [Machery] |
| 18612 | Americans are more inclined to refer causally than the Chinese are [Machery] |
| 18613 | Artifacts can be natural kinds, when they are the object of historical enquiry [Machery] |
| 21731 | Fields can be 'scalar', or 'vector', or 'tensor', or 'spinor' [Baggott] |
| 21730 | A 'field' is a property with a magnitude, distributed across all of space and time [Baggott] |
| 21732 | The current standard model requires 61 particles [Baggott] |