50 ideas
10482 | The logic of ZF is classical first-order predicate logic with identity [Boolos] |
10492 | A few axioms of set theory 'force themselves on us', but most of them don't [Boolos] |
18192 | Do the Replacement Axioms exceed the iterative conception of sets? [Boolos, by Maddy] |
7785 | The use of plurals doesn't commit us to sets; there do not exist individuals and collections [Boolos] |
10485 | Naïve sets are inconsistent: there is no set for things that do not belong to themselves [Boolos] |
10484 | The iterative conception says sets are formed at stages; some are 'earlier', and must be formed first [Boolos] |
13547 | Limitation of Size is weak (Fs only collect is something the same size does) or strong (fewer Fs than objects) [Boolos, by Potter] |
10699 | Does a bowl of Cheerios contain all its sets and subsets? [Boolos] |
14249 | Boolos reinterprets second-order logic as plural logic [Boolos, by Oliver/Smiley] |
10225 | Monadic second-order logic might be understood in terms of plural quantifiers [Boolos, by Shapiro] |
10830 | Second-order logic metatheory is set-theoretic, and second-order validity has set-theoretic problems [Boolos] |
10736 | Boolos showed how plural quantifiers can interpret monadic second-order logic [Boolos, by Linnebo] |
10780 | Any sentence of monadic second-order logic can be translated into plural first-order logic [Boolos, by Linnebo] |
10829 | A sentence can't be a truth of logic if it asserts the existence of certain sets [Boolos] |
10697 | Identity is clearly a logical concept, and greatly enhances predicate calculus [Boolos] |
8525 | Relations need terms, so they must be second-order entities based on first-order tropes [Campbell,K] |
10832 | '∀x x=x' only means 'everything is identical to itself' if the range of 'everything' is fixed [Boolos] |
13671 | Second-order quantifiers are just like plural quantifiers in ordinary language, with no extra ontology [Boolos, by Shapiro] |
10267 | We should understand second-order existential quantifiers as plural quantifiers [Boolos, by Shapiro] |
10698 | Plural forms have no more ontological commitment than to first-order objects [Boolos] |
7806 | Boolos invented plural quantification [Boolos, by Benardete,JA] |
10834 | Weak completeness: if it is valid, it is provable. Strong: it is provable from a set of sentences [Boolos] |
13841 | Why should compactness be definitive of logic? [Boolos, by Hacking] |
17818 | How many? must first partition an aggregate into sets, and then logic fixes its number [Yourgrau] |
17822 | Nothing is 'intrinsically' numbered [Yourgrau] |
10491 | Infinite natural numbers is as obvious as infinite sentences in English [Boolos] |
10483 | Mathematics and science do not require very high orders of infinity [Boolos] |
10833 | Many concepts can only be expressed by second-order logic [Boolos] |
17817 | Defining 'three' as the principle of collection or property of threes explains set theory definitions [Yourgrau] |
17815 | We can't use sets as foundations for mathematics if we must await results from the upper reaches [Yourgrau] |
17821 | You can ask all sorts of numerical questions about any one given set [Yourgrau] |
10490 | Mathematics isn't surprising, given that we experience many objects as abstract [Boolos] |
8518 | Events are trope-sequences, in which tropes replace one another [Campbell,K] |
10700 | First- and second-order quantifiers are two ways of referring to the same things [Boolos] |
8513 | Two red cloths are separate instances of redness, because you can dye one of them blue [Campbell,K] |
8514 | Red could only recur in a variety of objects if it was many, which makes them particulars [Campbell,K] |
8522 | Tropes solve the Companionship Difficulty, since the resemblance is only between abstract particulars [Campbell,K] |
8523 | Tropes solve the Imperfect Community problem, as they can only resemble in one respect [Campbell,K] |
8524 | Trope theory makes space central to reality, as tropes must have a shape and size [Campbell,K] |
10488 | It is lunacy to think we only see ink-marks, and not word-types [Boolos] |
8521 | Nominalism has the problem that without humans nothing would resemble anything else [Campbell,K] |
8515 | Tropes are basic particulars, so concrete particulars are collections of co-located tropes [Campbell,K] |
8519 | Bundles must be unique, so the Identity of Indiscernibles is a necessity - which it isn't! [Campbell,K] |
10487 | I am a fan of abstract objects, and confident of their existence [Boolos] |
10489 | We deal with abstract objects all the time: software, poems, mistakes, triangles.. [Boolos] |
4033 | Two pure spheres in non-absolute space are identical but indiscernible [Campbell,K] |
8512 | Abstractions come before the mind by concentrating on a part of what is presented [Campbell,K] |
8693 | An 'abstraction principle' says two things are identical if they are 'equivalent' in some respect [Boolos] |
8517 | Causal conditions are particular abstract instances of properties, which makes them tropes [Campbell,K] |
8516 | Davidson can't explain causation entirely by events, because conditions are also involved [Campbell,K] |