48 ideas
8092 | Logic was merely a branch of rhetoric until the scientific 17th century [Devlin] |
14092 | Philosophers are often too fussy about words, dismissing perfectly useful ordinary terms [Rosen] |
14100 | Figuring in the definition of a thing doesn't make it a part of that thing [Rosen] |
8081 | 'No councillors are bankers' and 'All bankers are athletes' implies 'Some athletes are not councillors' [Devlin] |
8085 | Modern propositional inference replaces Aristotle's 19 syllogisms with modus ponens [Devlin] |
8086 | Predicate logic retains the axioms of propositional logic [Devlin] |
18851 | Pairing (with Extensionality) guarantees an infinity of sets, just from a single element [Rosen] |
8091 | Situation theory is logic that takes account of context [Devlin] |
8087 | Golden ages: 1900-1960 for pure logic, and 1950-1985 for applied logic [Devlin] |
8089 | Montague's intensional logic incorporated the notion of meaning [Devlin] |
8082 | Where a conditional is purely formal, an implication implies a link between premise and conclusion [Devlin] |
8072 | Sentences of apparent identical form can have different contextual meanings [Devlin] |
14096 | Explanations fail to be monotonic [Rosen] |
8075 | Space and time are atomic in the arrow, and divisible in the tortoise [Devlin] |
14097 | Things could be true 'in virtue of' others as relations between truths, or between truths and items [Rosen] |
14095 | Facts are structures of worldly items, rather like sentences, individuated by their ingredients [Rosen] |
14093 | An 'intrinsic' property is one that depends on a thing and its parts, and not on its relations [Rosen] |
8915 | How we refer to abstractions is much less clear than how we refer to other things [Rosen] |
18852 | A Meinongian principle might say that there is an object for any modest class of properties [Rosen] |
18849 | Metaphysical necessity is absolute and universal; metaphysical possibility is very tolerant [Rosen] |
18850 | 'Metaphysical' modality is the one that makes the necessity or contingency of laws of nature interesting [Rosen] |
18858 | Sets, universals and aggregates may be metaphysically necessary in one sense, but not another [Rosen] |
14094 | The excellent notion of metaphysical 'necessity' cannot be defined [Rosen] |
18857 | Standard Metaphysical Necessity: P holds wherever the actual form of the world holds [Rosen] |
18856 | Non-Standard Metaphysical Necessity: when ¬P is incompatible with the nature of things [Rosen] |
18848 | Something may be necessary because of logic, but is that therefore a special sort of necessity? [Rosen] |
18855 | Combinatorial theories of possibility assume the principles of combination don't change across worlds [Rosen] |
14101 | Are necessary truths rooted in essences, or also in basic grounding laws? [Rosen] |
18853 | A proposition is 'correctly' conceivable if an ominiscient being could conceive it [Rosen] |
411 | If we succeed in speaking the truth, we cannot know we have done it [Xenophanes] |
412 | If God had not created honey, men would say figs are sweeter [Xenophanes] |
8088 | People still say the Hopi have no time concepts, despite Whorf's later denial [Devlin] |
8917 | The Way of Abstraction used to say an abstraction is an idea that was formed by abstracting [Rosen] |
8912 | Nowadays abstractions are defined as non-spatial, causally inert things [Rosen] |
8913 | Chess may be abstract, but it has existed in specific space and time [Rosen] |
8914 | Sets are said to be abstract and non-spatial, but a set of books can be on a shelf [Rosen] |
8916 | Conflating abstractions with either sets or universals is a big claim, needing a big defence [Rosen] |
8918 | Functional terms can pick out abstractions by asserting an equivalence relation [Rosen] |
8919 | Abstraction by equivalence relationships might prove that a train is an abstract entity [Rosen] |
8073 | How do we parse 'time flies like an arrow' and 'fruit flies like an apple'? [Devlin] |
8076 | The distinction between sentences and abstract propositions is crucial in logic [Devlin] |
14099 | 'Bachelor' consists in or reduces to 'unmarried' male, but not the other way around [Rosen] |
1640 | The basic Eleatic belief was that all things are one [Xenophanes, by Plato] |
18854 | The MRL view says laws are the theorems of the simplest and strongest account of the world [Rosen] |
14098 | An acid is just a proton donor [Rosen] |
3055 | Xenophanes said the essence of God was spherical and utterly inhuman [Xenophanes, by Diog. Laertius] |
408 | Ethiopian gods have black hair, and Thracian gods have red hair [Xenophanes] |
407 | Mortals believe gods are born, and have voices and clothes just like mortals [Xenophanes] |