59 ideas
| 15169 | Metaphysics is clarifying how we speak and think (and possibly improving it) [Sidelle] |
| 15164 | We seem to base necessities on thought experiments and imagination [Sidelle] |
| 13913 | The four 'perfect syllogisms' are called Barbara, Celarent, Darii and Ferio [Engelbretsen/Sayward] |
| 13914 | Syllogistic logic has one rule: what is affirmed/denied of wholes is affirmed/denied of their parts [Engelbretsen/Sayward] |
| 13915 | Syllogistic can't handle sentences with singular terms, or relational terms, or compound sentences [Engelbretsen/Sayward] |
| 13916 | Term logic uses expression letters and brackets, and '-' for negative terms, and '+' for compound terms [Engelbretsen/Sayward] |
| 10676 | The Axiom of Choice is a non-logical principle of set-theory [Hossack] |
| 10686 | The Axiom of Choice guarantees a one-one correspondence from sets to ordinals [Hossack] |
| 23623 | Predicativism says only predicated sets exist [Hossack] |
| 23624 | The iterative conception has to appropriate Replacement, to justify the ordinals [Hossack] |
| 23625 | Limitation of Size justifies Replacement, but then has to appropriate Power Set [Hossack] |
| 10687 | Maybe we reduce sets to ordinals, rather than the other way round [Hossack] |
| 10677 | Extensional mereology needs two definitions and two axioms [Hossack] |
| 13850 | In modern logic all formal validity can be characterised syntactically [Engelbretsen/Sayward] |
| 13849 | Classical logic rests on truth and models, where constructivist logic rests on defence and refutation [Engelbretsen/Sayward] |
| 13851 | Unlike most other signs, = cannot be eliminated [Engelbretsen/Sayward] |
| 23628 | The connective 'and' can have an order-sensitive meaning, as 'and then' [Hossack] |
| 23627 | 'Before' and 'after' are not two relations, but one relation with two orders [Hossack] |
| 10671 | Plural definite descriptions pick out the largest class of things that fit the description [Hossack] |
| 10666 | Plural reference will refer to complex facts without postulating complex things [Hossack] |
| 10669 | Plural reference is just an abbreviation when properties are distributive, but not otherwise [Hossack] |
| 10675 | A plural comprehension principle says there are some things one of which meets some condition [Hossack] |
| 13852 | Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't [Engelbretsen/Sayward] |
| 10673 | Plural language can discuss without inconsistency things that are not members of themselves [Hossack] |
| 10680 | The theory of the transfinite needs the ordinal numbers [Hossack] |
| 10684 | I take the real numbers to be just lengths [Hossack] |
| 23626 | Transfinite ordinals are needed in proof theory, and for recursive functions and computability [Hossack] |
| 10674 | A plural language gives a single comprehensive induction axiom for arithmetic [Hossack] |
| 10681 | In arithmetic singularists need sets as the instantiator of numeric properties [Hossack] |
| 10685 | Set theory is the science of infinity [Hossack] |
| 23621 | Numbers are properties, not sets (because numbers are magnitudes) [Hossack] |
| 23622 | We can only mentally construct potential infinities, but maths needs actual infinities [Hossack] |
| 10668 | We are committed to a 'group' of children, if they are sitting in a circle [Hossack] |
| 15180 | There doesn't seem to be anything in the actual world that can determine modal facts [Sidelle] |
| 10664 | Complex particulars are either masses, or composites, or sets [Hossack] |
| 10678 | The relation of composition is indispensable to the part-whole relation for individuals [Hossack] |
| 10682 | The fusion of five rectangles can decompose into more than five parts that are rectangles [Hossack] |
| 10665 | Leibniz's Law argues against atomism - water is wet, unlike water molecules [Hossack] |
| 15184 | Causal reference presupposes essentialism if it refers to modally extended entities [Sidelle] |
| 15172 | Clearly, essential predications express necessary properties [Sidelle] |
| 15181 | Being a deepest explanatory feature is an actual, not a modal property [Sidelle] |
| 15173 | That the essence of water is its microstructure is a convention, not a discovery [Sidelle] |
| 15185 | We aren't clear about 'same stuff as this', so a principle of individuation is needed to identify it [Sidelle] |
| 15175 | Evaluation of de dicto modalities does not depend on the identity of its objects [Sidelle] |
| 15032 | Necessary a posteriori is conventional for necessity and nonmodal for a posteriority [Sidelle, by Sider] |
| 15179 | To know empirical necessities, we need empirical facts, plus conventions about which are necessary [Sidelle] |
| 15171 | The necessary a posteriori is statements either of identity or of essence [Sidelle] |
| 15167 | Empiricism explores necessities and concept-limits by imagining negations of truths [Sidelle] |
| 15177 | Contradictoriness limits what is possible and what is imaginable [Sidelle] |
| 15176 | The individuals and kinds involved in modality are also a matter of convention [Sidelle] |
| 15174 | A thing doesn't need transworld identity prior to rigid reference - that could be a convention of the reference [Sidelle] |
| 15183 | 'Dthat' operates to make a singular term into a rigid term [Sidelle] |
| 15165 | A priori knowledge is entirely of analytic truths [Sidelle] |
| 10663 | A thought can refer to many things, but only predicate a universal and affirm a state of affairs [Hossack] |
| 15168 | That water is essentially H2O in some way concerns how we use 'water' [Sidelle] |
| 15166 | Causal reference seems to get directly at the object, thus leaving its nature open [Sidelle] |
| 15182 | Because some entities overlap, reference must have analytic individuation principles [Sidelle] |
| 15178 | Can anything in science reveal the necessity of what it discovers? [Sidelle] |
| 10683 | We could ignore space, and just talk of the shape of matter [Hossack] |