120 ideas
| 22659 | It is wisdom to believe what you desire, because belief is needed to achieve it [James] |
| 22657 | All good philosophers start from a dumb conviction about which truths can be revealed [James] |
| 22647 | A complete system is just a classification of the whole world's ingredients [James] |
| 14092 | Philosophers are often too fussy about words, dismissing perfectly useful ordinary terms [Rosen] |
| 22648 | A single explanation must have a single point of view [James] |
| 22642 | Man has an intense natural interest in the consistency of his own thinking [James] |
| 22644 | Our greatest pleasure is the economy of reducing chaotic facts to one single fact [James] |
| 14100 | Figuring in the definition of a thing doesn't make it a part of that thing [Rosen] |
| 6710 | You can only define a statement that something is 'true' by referring to its functional possibilities [James] |
| 18986 | Truth is just a name for verification-processes [James] |
| 18983 | In many cases there is no obvious way in which ideas can agree with their object [James] |
| 18972 | Ideas are true in so far as they co-ordinate our experiences [James] |
| 18973 | New opinions count as 'true' if they are assimilated to an individual's current beliefs [James] |
| 18984 | True ideas are those we can assimilate, validate, corroborate and verify (and false otherwise) [James] |
| 22305 | If the hypothesis of God is widely successful, it is true [James] |
| 10073 | There cannot be a set theory which is complete [Smith,P] |
| 18851 | Pairing (with Extensionality) guarantees an infinity of sets, just from a single element [Rosen] |
| 10616 | Second-order arithmetic can prove new sentences of first-order [Smith,P] |
| 10076 | The 'range' of a function is the set of elements in the output set created by the function [Smith,P] |
| 10605 | Two functions are the same if they have the same extension [Smith,P] |
| 10075 | A 'partial function' maps only some elements to another set [Smith,P] |
| 10074 | A 'total function' maps every element to one element in another set [Smith,P] |
| 10612 | An argument is a 'fixed point' for a function if it is mapped back to itself [Smith,P] |
| 10615 | The Comprehension Schema says there is a property only had by things satisfying a condition [Smith,P] |
| 10595 | A 'theorem' of a theory is a sentence derived from the axioms using the proof system [Smith,P] |
| 10602 | A 'natural deduction system' has no axioms but many rules [Smith,P] |
| 10613 | No nice theory can define truth for its own language [Smith,P] |
| 10078 | An 'injective' ('one-to-one') function creates a distinct output element from each original [Smith,P] |
| 10077 | A 'surjective' ('onto') function creates every element of the output set [Smith,P] |
| 10079 | A 'bijective' function has one-to-one correspondence in both directions [Smith,P] |
| 10070 | If everything that a theory proves is true, then it is 'sound' [Smith,P] |
| 10086 | Soundness is true axioms and a truth-preserving proof system [Smith,P] |
| 10596 | A theory is 'sound' iff every theorem is true (usually from true axioms and truth-preservation) [Smith,P] |
| 10598 | A theory is 'negation complete' if it proves all sentences or their negation [Smith,P] |
| 10597 | 'Complete' applies both to whole logics, and to theories within them [Smith,P] |
| 10069 | A theory is 'negation complete' if one of its sentences or its negation can always be proved [Smith,P] |
| 10609 | Two routes to Incompleteness: semantics of sound/expressible, or syntax of consistency/proof [Smith,P] |
| 10080 | 'Effective' means simple, unintuitive, independent, controlled, dumb, and terminating [Smith,P] |
| 10087 | A theory is 'decidable' if all of its sentences could be mechanically proved [Smith,P] |
| 10088 | Any consistent, axiomatized, negation-complete formal theory is decidable [Smith,P] |
| 10081 | A set is 'enumerable' is all of its elements can result from a natural number function [Smith,P] |
| 10083 | A set is 'effectively enumerable' if a computer could eventually list every member [Smith,P] |
| 10084 | A finite set of finitely specifiable objects is always effectively enumerable (e.g. primes) [Smith,P] |
| 10085 | The set of ordered pairs of natural numbers <i,j> is effectively enumerable [Smith,P] |
| 10601 | The thorems of a nice arithmetic can be enumerated, but not the truths (so they're diffferent) [Smith,P] |
| 10600 | Being 'expressible' depends on language; being 'capture/represented' depends on axioms and proof system [Smith,P] |
| 14096 | Explanations fail to be monotonic [Rosen] |
| 10599 | For primes we write (x not= 1 ∧ ∀u∀v(u x v = x → (u = 1 ∨ v = 1))) [Smith,P] |
| 10610 | The reals contain the naturals, but the theory of reals doesn't contain the theory of naturals [Smith,P] |
| 10619 | The truths of arithmetic are just true equations and their universally quantified versions [Smith,P] |
| 10608 | The number of Fs is the 'successor' of the Gs if there is a single F that isn't G [Smith,P] |
| 10618 | All numbers are related to zero by the ancestral of the successor relation [Smith,P] |
| 10849 | Baby arithmetic covers addition and multiplication, but no general facts about numbers [Smith,P] |
| 10850 | Baby Arithmetic is complete, but not very expressive [Smith,P] |
| 10851 | Robinson Arithmetic 'Q' has basic axioms, quantifiers and first-order logic [Smith,P] |
| 10852 | Robinson Arithmetic (Q) is not negation complete [Smith,P] |
| 10068 | Natural numbers have zero, unique successors, unending, no circling back, and no strays [Smith,P] |
| 10603 | The logic of arithmetic must quantify over properties of numbers to handle induction [Smith,P] |
| 10848 | Multiplication only generates incompleteness if combined with addition and successor [Smith,P] |
| 10604 | Incompleteness results in arithmetic from combining addition and successor with multiplication [Smith,P] |
| 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] |
| 22641 | Realities just are, and beliefs are true of them [James] |
| 22649 | Classification can only ever be for a particular purpose [James] |
| 10617 | The 'ancestral' of a relation is a new relation which creates a long chain of the original relation [Smith,P] |
| 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] |
| 18987 | A 'thing' is simply carved out of reality for human purposes [James] |
| 18981 | 'Substance' is just a word for groupings and structures in experience [James] |
| 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] |
| 18974 | Truth is a species of good, being whatever proves itself good in the way of belief [James] |
| 18989 | Pragmatism accepts any hypothesis which has useful consequences [James] |
| 22640 | We find satisfaction in consistency of all of our beliefs, perceptions and mental connections [James] |
| 22655 | Scientific genius extracts more than other people from the same evidence [James] |
| 22658 | Experimenters assume the theory is true, and stick to it as long as result don't disappoint [James] |
| 18971 | Theories are practical tools for progress, not answers to enigmas [James] |
| 18985 | True thoughts are just valuable instruments of action [James] |
| 18982 | Pragmatism says all theories are instrumental - that is, mental modes of adaptation to reality [James] |
| 22654 | We can't know if the laws of nature are stable, but we must postulate it or assume it [James] |
| 22656 | Trying to assess probabilities by mere calculation is absurd and impossible [James] |
| 22646 | We have a passion for knowing the parts of something, rather than the whole [James] |
| 22652 | The mind has evolved entirely for practical interests, seen in our reflex actions [James] |
| 22651 | Dogs' curiosity only concerns what will happen next [James] |
| 9286 | Consciousness is not a stuff, but is explained by the relations between experiences [James] |
| 9285 | 'Consciousness' is a nonentity, a mere echo of the disappearing 'soul' [James] |
| 23981 | Rage is inconceivable without bodily responses; so there are no disembodied emotions [James] |
| 22650 | How can the ground of rationality be itself rational? [James] |
| 22643 | It seems that we feel rational when we detect no irrationality [James] |
| 18975 | We return to experience with concepts, where they show us differences [James] |
| 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] |
| 14099 | 'Bachelor' consists in or reduces to 'unmarried' male, but not the other way around [Rosen] |
| 22660 | Evolution suggests prevailing or survival as a new criterion of right and wrong [James] |
| 6570 | Imagine millions made happy on condition that one person suffers endless lonely torture [James] |
| 22645 | Understanding by means of causes is useless if they are not reduced to a minimum number [James] |
| 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] |
| 18980 | If there is a 'greatest knower', it doesn't follow that they know absolutely everything [James] |
| 18978 | It is hard to grasp a cosmic mind which produces such a mixture of goods and evils [James] |
| 18991 | If the God hypothesis works well, then it is true [James] |
| 18977 | The wonderful design of a woodpecker looks diabolical to its victims [James] |
| 18979 | Things with parts always have some structure, so they always appear to be designed [James] |
| 18976 | Private experience is the main evidence for God [James] |
| 22653 | Early Christianity says God recognises the neglected weak and tender impulses [James] |
| 18990 | Nirvana means safety from sense experience, and hindus and buddhists are just afraid of life [James] |