241 ideas
| 6779 | Instrumentalists say distinctions between observation and theory vanish with ostensive definition [Bird] |
| 10237 | Coherence is a primitive, intuitive notion, not reduced to something formal [Shapiro] |
| 10204 | An 'implicit definition' gives a direct description of the relations of an entity [Shapiro] |
| 13634 | Satisfaction is 'truth in a model', which is a model of 'truth' [Shapiro] |
| 13643 | Aristotelian logic is complete [Shapiro] |
| 10206 | Modal operators are usually treated as quantifiers [Shapiro] |
| 9449 | The plausible Barcan formula implies modality in the actual world [Bird] |
| 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] |
| 10208 | Axiom of Choice: some function has a value for every set in a given set [Shapiro] |
| 10252 | The Axiom of Choice seems to license an infinite amount of choosing [Shapiro] |
| 10301 | The axiom of choice is controversial, but it could be replaced [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] |
| 10207 | Anti-realists reject set theory [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] |
| 10588 | First-order logic is Complete, and Compact, with the Löwenheim-Skolem Theorems [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] |
| 10298 | Some say that second-order logic is mathematics, not logic [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] |
| 10299 | If the aim of logic is to codify inferences, second-order logic is useless [Shapiro] |
| 10300 | Logical consequence can be defined in terms of the logical terminology [Shapiro] |
| 10259 | The two standard explanations of consequence are semantic (in models) and deductive [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] |
| 10257 | Intuitionism only sanctions modus ponens if all three components are proved [Shapiro] |
| 10253 | Either logic determines objects, or objects determine logic, or they are separate [Shapiro] |
| 10251 | The law of excluded middle might be seen as a principle of omniscience [Shapiro] |
| 8729 | Intuitionists deny excluded middle, because it is committed to transcendent truth or objects [Shapiro] |
| 13632 | Finding the logical form of a sentence is difficult, and there are no criteria of correctness [Shapiro] |
| 10212 | Classical connectives differ from their ordinary language counterparts; '∧' is timeless, unlike 'and' [Shapiro] |
| 10209 | A function is just an arbitrary correspondence between collections [Shapiro] |
| 13674 | We might reduce ontology by using truth of sentences and terms, instead of using objects satisfying models [Shapiro] |
| 10290 | Second-order variables also range over properties, sets, relations or functions [Shapiro] |
| 10268 | Maybe plural quantifiers should be understood in terms of classes or sets [Shapiro] |
| 10235 | A sentence is 'satisfiable' if it has a model [Shapiro] |
| 13633 | 'Satisfaction' is a function from models, assignments, and formulas to {true,false} [Shapiro] |
| 13644 | Semantics for models uses set-theory [Shapiro] |
| 10240 | Model theory deals with relations, reference and extensions [Shapiro] |
| 10239 | The central notion of model theory is the relation of 'satisfaction' [Shapiro] |
| 13670 | Categoricity can't be reached in a first-order language [Shapiro] |
| 10214 | Theory ontology is never complete, but is only determined 'up to isomorphism' [Shapiro] |
| 10238 | The set-theoretical hierarchy contains as many isomorphism types as possible [Shapiro] |
| 13636 | An axiomatization is 'categorical' if its models are isomorphic, so there is really only one interpretation [Shapiro] |
| 10590 | Up Löwenheim-Skolem: if natural numbers satisfy wffs, then an infinite domain satisfies them [Shapiro] |
| 10296 | The Löwenheim-Skolem Theorems fail for second-order languages with standard semantics [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] |
| 10297 | The Löwenheim-Skolem theorem seems to be a defect of first-order logic [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] |
| 10292 | Downward Löwenheim-Skolem: if there's an infinite model, there is a countable model [Shapiro] |
| 10234 | Any theory with an infinite model has a model of every infinite cardinality [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] |
| 10201 | Virtually all of mathematics can be modeled in set theory [Shapiro] |
| 13641 | Complex numbers can be defined as reals, which are defined as rationals, then integers, then naturals [Shapiro] |
| 8763 | The number 3 is presumably identical as a natural, an integer, a rational, a real, and complex [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] |
| 10213 | Real numbers are thought of as either Cauchy sequences or Dedekind cuts [Shapiro] |
| 18243 | Understanding the real-number structure is knowing usage of the axiomatic language of analysis [Shapiro] |
| 18249 | Cauchy gave a formal definition of a converging sequence. [Shapiro] |
| 18245 | Cuts are made by the smallest upper or largest lower number, some of them not rational [Shapiro] |
| 13652 | The 'continuum' is the cardinality of the powerset of a denumerably infinite set [Shapiro] |
| 10236 | There is no grounding for mathematics that is more secure than mathematics [Shapiro] |
| 8764 | Categories are the best foundation for mathematics [Shapiro] |
| 10256 | For intuitionists, proof is inherently informal [Shapiro] |
| 13657 | First-order arithmetic can't even represent basic number theory [Shapiro] |
| 10202 | Natural numbers just need an initial object, successors, and an induction principle [Shapiro] |
| 10294 | Second-order logic has the expressive power for mathematics, but an unworkable model theory [Shapiro] |
| 10205 | Mathematics originally concerned the continuous (geometry) and the discrete (arithmetic) [Shapiro] |
| 8762 | Two definitions of 3 in terms of sets disagree over whether 1 is a member of 3 [Shapiro] |
| 13656 | Some sets of natural numbers are definable in set-theory but not in arithmetic [Shapiro] |
| 10222 | Mathematical foundations may not be sets; categories are a popular rival [Shapiro] |
| 10218 | Baseball positions and chess pieces depend entirely on context [Shapiro] |
| 10224 | The even numbers have the natural-number structure, with 6 playing the role of 3 [Shapiro] |
| 10228 | Could infinite structures be apprehended by pattern recognition? [Shapiro] |
| 10230 | The 4-pattern is the structure common to all collections of four objects [Shapiro] |
| 10249 | The main mathematical structures are algebraic, ordered, and topological [Shapiro] |
| 10273 | Some structures are exemplified by both abstract and concrete [Shapiro] |
| 10276 | Mathematical structures are defined by axioms, or in set theory [Shapiro] |
| 8760 | Numbers do not exist independently; the essence of a number is its relations to other numbers [Shapiro] |
| 8761 | A 'system' is related objects; a 'pattern' or 'structure' abstracts the pure relations from them [Shapiro] |
| 10270 | The main versions of structuralism are all definitionally equivalent [Shapiro] |
| 10221 | Is there is no more to structures than the systems that exemplify them? [Shapiro] |
| 10248 | Number statements are generalizations about number sequences, and are bound variables [Shapiro] |
| 10220 | Because one structure exemplifies several systems, a structure is a one-over-many [Shapiro] |
| 10223 | There is no 'structure of all structures', just as there is no set of all sets [Shapiro] |
| 8703 | Shapiro's structuralism says model theory (comparing structures) is the essence of mathematics [Shapiro, by Friend] |
| 10274 | Does someone using small numbers really need to know the infinite structure of arithmetic? [Shapiro] |
| 10200 | We distinguish realism 'in ontology' (for objects), and 'in truth-value' (for being either true or false) [Shapiro] |
| 10210 | If mathematical objects are accepted, then a number of standard principles will follow [Shapiro] |
| 10215 | Platonists claim we can state the essence of a number without reference to the others [Shapiro] |
| 10233 | Platonism must accept that the Peano Axioms could all be false [Shapiro] |
| 10244 | Intuition is an outright hindrance to five-dimensional geometry [Shapiro] |
| 10280 | A stone is a position in some pattern, and can be viewed as an object, or as a location [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] |
| 8744 | Logicism seems to be a non-starter if (as is widely held) logic has no ontology of its own [Shapiro] |
| 8749 | Term Formalism says mathematics is just about symbols - but real numbers have no names [Shapiro] |
| 8750 | Game Formalism is just a matter of rules, like chess - but then why is it useful in science? [Shapiro] |
| 8752 | Deductivism says mathematics is logical consequences of uninterpreted axioms [Shapiro] |
| 10254 | Can the ideal constructor also destroy objects? [Shapiro] |
| 10255 | Presumably nothing can block a possible dynamic operation? [Shapiro] |
| 8753 | Critics resent the way intuitionism cripples mathematics, but it allows new important distinctions [Shapiro] |
| 8731 | Conceptualist are just realists or idealist or nominalists, depending on their view of concepts [Shapiro] |
| 13663 | Some reject formal properties if they are not defined, or defined impredicatively [Shapiro] |
| 8730 | 'Impredicative' definitions refer to the thing being described [Shapiro] |
| 10279 | Can we discover whether a deck is fifty-two cards, or a person is time-slices or molecules? [Shapiro] |
| 9501 | If all existents are causally active, that excludes abstracta and causally isolated objects [Bird] |
| 9500 | If naturalism refers to supervenience, that leaves necessary entities untouched [Bird] |
| 10227 | The abstract/concrete boundary now seems blurred, and would need a defence [Shapiro] |
| 10226 | Mathematicians regard arithmetic as concrete, and group theory as abstract [Shapiro] |
| 6780 | Anti-realism is more plausible about laws than about entities and theories [Bird] |
| 10262 | Fictionalism eschews the abstract, but it still needs the possible (without model theory) [Shapiro] |
| 10277 | Structuralism blurs the distinction between mathematical and ordinary objects [Shapiro] |
| 9502 | There might be just one fundamental natural property [Bird] |
| 9477 | Categorical properties are not modally fixed, but change across possible worlds [Bird] |
| 9490 | The categoricalist idea is that a property is only individuated by being itself [Bird] |
| 9495 | If we abstractly define a property, that doesn't mean some object could possess it [Bird] |
| 9492 | Categoricalists take properties to be quiddities, with no essential difference between them [Bird] |
| 13638 | Properties are often seen as intensional; equiangular and equilateral are different, despite identity of objects [Shapiro] |
| 9503 | To name an abundant property is either a Fregean concept, or a simple predicate [Bird] |
| 10591 | Logicians use 'property' and 'set' interchangeably, with little hanging on it [Shapiro] |
| 14540 | Only real powers are fundamental [Bird, by Mumford/Anjum] |
| 9450 | If all properties are potencies, and stimuli and manifestation characterise them, there is a regress [Bird] |
| 9498 | The essence of a potency involves relations, e.g. mass, to impressed force and acceleration [Bird] |
| 9474 | A disposition is finkish if a time delay might mean the manifestation fizzles out [Bird] |
| 9475 | A robust pot attached to a sensitive bomb is not fragile, but if struck it will easily break [Bird] |
| 9499 | Megarian actualists deny unmanifested dispositions [Bird] |
| 9486 | Why should a universal's existence depend on instantiation in an existing particular? [Bird] |
| 9472 | Resemblance itself needs explanation, presumably in terms of something held in common [Bird] |
| 10272 | The notion of 'object' is at least partially structural and mathematical [Shapiro] |
| 10275 | A blurry border is still a border [Shapiro] |
| 9482 | If the laws necessarily imply p, that doesn't give a new 'nomological' necessity [Bird] |
| 10258 | Logical modalities may be acceptable, because they are reducible to satisfaction in models [Shapiro] |
| 9481 | Logical necessitation is not a kind of necessity; George Orwell not being Eric Blair is not a real possibility [Bird] |
| 6796 | Subjective probability measures personal beliefs; objective probability measures the chance of an event happening [Bird] |
| 6797 | Objective probability of tails measures the bias of the coin, not our beliefs about it [Bird] |
| 9505 | Empiricist saw imaginability and possibility as close, but now they seem remote [Bird] |
| 10266 | Why does the 'myth' of possible worlds produce correct modal logic? [Shapiro] |
| 9491 | Haecceitism says identity is independent of qualities and without essence [Bird] |
| 8725 | Rationalism tries to apply mathematical methodology to all of knowledge [Shapiro] |
| 6800 | Many philosophers rate justification as a more important concept than knowledge [Bird] |
| 6786 | As science investigates more phenomena, the theories it needs decreases [Bird] |
| 6792 | If theories need observation, and observations need theories, how do we start? [Bird] |
| 6757 | Explanation predicts after the event; prediction explains before the event [Bird] |
| 6777 | Realists say their theories involve truth and the existence of their phenomena [Bird] |
| 6804 | There is no agreement on scientific method - because there is no such thing [Bird] |
| 6805 | Relativity ousted Newtonian mechanics despite a loss of simplicity [Bird] |
| 6778 | Instrumentalists regard theories as tools for prediction, with truth being irrelevant [Bird] |
| 6775 | Induction is inference to the best explanation, where the explanation is a law [Bird] |
| 6791 | If Hume is right about induction, there is no scientific knowledge [Bird] |
| 6790 | Anything justifying inferences from observed to unobserved must itself do that [Bird] |
| 6738 | Any conclusion can be drawn from an induction, if we use grue-like predicates [Bird] |
| 6739 | Several months of observing beech trees supports the deciduous and evergreen hypotheses [Bird] |
| 6799 | We normally learn natural kinds from laws, but Goodman shows laws require prior natural kinds [Bird] |
| 6798 | Bayesianism claims to find rationality and truth in induction, and show how science works [Bird] |
| 6752 | The objective component of explanations is the things that must exist for the explanation [Bird] |
| 6754 | We talk both of 'people' explaining things, and of 'facts' explaining things [Bird] |
| 9487 | We can't reject all explanations because of a regress; inexplicable A can still explain B [Bird] |
| 6750 | Explanations are causal, nomic, psychological, psychoanalytic, Darwinian or functional [Bird] |
| 6761 | Contrastive explanations say why one thing happened but not another [Bird] |
| 6758 | 'Covering law' explanations only work if no other explanations are to be found [Bird] |
| 6759 | Livers always accompany hearts, but they don't explain hearts [Bird] |
| 20653 | Six reduction levels: groups, lives, cells, molecules, atoms, particles [Putnam/Oppenheim, by Watson] |
| 6756 | Probabilistic-statistical explanations don't entail the explanandum, but makes it more likely [Bird] |
| 6760 | An operation might reduce the probability of death, yet explain a death [Bird] |
| 6785 | Inference to the Best Explanation is done with facts, so it has to be realist [Bird] |
| 6788 | Maybe bad explanations are the true ones, in this messy world [Bird] |
| 6787 | Which explanation is 'best' is bound to be subjective, and no guide to truth [Bird] |
| 6751 | Maybe explanation is so subjective that it cannot be a part of science [Bird] |
| 10203 | We apprehend small, finite mathematical structures by abstraction from patterns [Shapiro] |
| 17527 | Causation seems to be an innate concept (or acquired very early) [Bird] |
| 10229 | Simple types can be apprehended through their tokens, via abstraction [Shapiro] |
| 9626 | A structure is an abstraction, focussing on relationships, and ignoring other features [Shapiro] |
| 10217 | We can apprehend structures by focusing on or ignoring features of patterns [Shapiro] |
| 9554 | We can focus on relations between objects (like baseballers), ignoring their other features [Shapiro] |
| 10231 | Abstract objects might come by abstraction over an equivalence class of base entities [Shapiro] |
| 6776 | Natural kinds are those that we use in induction [Bird] |
| 6767 | Rubies and sapphires are both corundum, with traces of metals varying their colours [Bird] |
| 6768 | Tin is not one natural kind, but appears to be 21, depending on isotope [Bird] |
| 6770 | Membership of a purely random collection cannot be used as an explanation [Bird] |
| 6771 | Natural kinds may overlap, or be sub-kinds of one another [Bird] |
| 6773 | If F is a universal appearing in a natural law, then Fs form a natural kind [Bird] |
| 6769 | In the Kripke-Putnam view only nuclear physicists can know natural kinds [Bird] |
| 6774 | Darwinism suggests that we should have a native ability to detect natural kinds [Bird] |
| 6764 | Nominal essence of a natural kind is the features that make it fit its name [Bird] |
| 6766 | Jadeite and nephrite are superficially identical, but have different composition [Bird] |
| 6808 | Reference to scientific terms is by explanatory role, not by descriptions [Bird] |
| 17528 | The dispositional account explains causation, as stimulation and manifestation of dispositions [Bird] |
| 9493 | We should explain causation by powers, not powers by causation [Bird] |
| 6753 | Laws are more fundamental in science than causes, and laws will explain causes [Bird] |
| 9494 | Singularism about causes is wrong, as the universals involved imply laws [Bird] |
| 17526 | The counterfactual approach makes no distinction between cause and pre-condition [Bird] |
| 6762 | Newton's laws cannot be confirmed individually, but only in combinations [Bird] |
| 6763 | Parapsychology is mere speculation, because it offers no mechanisms for its working [Bird] |
| 6772 | Existence requires laws, as inertia or gravity are needed for mass or matter [Bird] |
| 9507 | Laws are explanatory relationships of things, which supervene on their essences [Bird] |
| 9488 | Laws are either disposition regularities, or relations between properties [Bird] |
| 6740 | 'All uranium lumps are small' is a law, but 'all gold lumps are small' is not [Bird] |
| 6741 | There can be remarkable uniformities in nature that are purely coincidental [Bird] |
| 6742 | A law might have no instances, if it was about things that only exist momentarily [Bird] |
| 6743 | If laws are just instances, the law should either have gaps, or join the instances arbitrarily [Bird] |
| 6744 | Where is the regularity in a law predicting nuclear decay? [Bird] |
| 6747 | Laws cannot explain instances if they are regularities, as something can't explain itself [Bird] |
| 9496 | That other diamonds are hard does not explain why this one is [Bird] |
| 6748 | Similar appearance of siblings is a regularity, but shared parents is what links them [Bird] |
| 6749 | We can only infer a true regularity if something binds the instances together [Bird] |
| 6803 | If we only infer laws from regularities among observations, we can't infer unobservable entities. [Bird] |
| 6801 | Accidental regularities are not laws, and an apparent regularity may not be actual [Bird] |
| 9479 | Dispositional essentialism says laws (and laws about laws) are guaranteed regularities [Bird] |
| 6746 | There may be many laws, each with only a few instances [Bird] |
| 6745 | A regularity is only a law if it is part of a complete system which is simple and strong [Bird] |
| 6802 | With strange enough predicates, anything could be made out to be a regularity [Bird] |
| 9473 | Laws cannot offer unified explanations if they don't involve universals [Bird] |
| 9484 | If the universals for laws must be instantiated, a vanishing particular could destroy a law [Bird] |
| 9506 | Salt necessarily dissolves in water, because of the law which makes the existence of salt possible [Bird] |
| 23713 | Most laws supervene on fundamental laws, which are explained by basic powers [Bird, by Friend/Kimpton-Nye] |
| 6789 | If flame colour is characteristic of a metal, that is an empirical claim needing justification [Bird] |
| 9489 | Essentialism can't use conditionals to explain regularities, because of possible interventions [Bird] |
| 6807 | In Newton mass is conserved, but in Einstein it can convert into energy [Bird] |
| 9504 | The relational view of space-time doesn't cover times and places where things could be [Bird] |