153 ideas
| 12997 | Analysis is the art of finding the middle term [Leibniz] |
| 22270 | Frege changed philosophy by extending logic's ability to check the grounds of thinking [Potter on Frege] |
| 13009 | A reason is a known truth which leads to assent to some further truth [Leibniz] |
| 12963 | Opposing reason is opposing truth, since reason is a chain of truths [Leibniz] |
| 19360 | General principles, even if unconscious, are indispensable for thinking [Leibniz] |
| 8939 | We should not describe human laws of thought, but how to correctly track truth [Frege, by Fisher] |
| 12983 | A nominal definition is of the qualities, but the real definition is of the essential inner structure [Leibniz] |
| 12982 | One essence can be expressed by several definitions [Leibniz] |
| 12976 | If our ideas of a thing are imperfect, the thing can have several unconnected definitions [Leibniz] |
| 12984 | Real definitions, unlike nominal definitions, display possibilities [Leibniz] |
| 12980 | Genus and differentia might be swapped, and 'rational animal' become 'animable rational' [Leibniz] |
| 13000 | Truth is correspondence between mental propositions and what they are about [Leibniz] |
| 15879 | The Square of Opposition has two contradictory pairs, one contrary pair, and one sub-contrary pair [Harré] |
| 4971 | I don't use 'subject' and 'predicate' in my way of representing a judgement [Frege] |
| 17745 | For Frege, 'All A's are B's' means that the concept A implies the concept B [Frege, by Walicki] |
| 7728 | Frege has a judgement stroke (vertical, asserting or judging) and a content stroke (horizontal, expressing) [Frege, by Weiner] |
| 16881 | The laws of logic are boundless, so we want the few whose power contains the others [Frege] |
| 7622 | In 1879 Frege developed second order logic [Frege, by Putnam] |
| 12992 | Logic teaches us how to order and connect our thoughts [Leibniz] |
| 10056 | At bottom eternal truths are all conditional [Leibniz] |
| 7729 | Frege replaced Aristotle's subject/predicate form with function/argument form [Frege, by Weiner] |
| 12974 | People who can't apply names usually don't understand the thing to which it applies [Leibniz] |
| 9950 | A quantifier is a second-level predicate (which explains how it contributes to truth-conditions) [Frege, by George/Velleman] |
| 15891 | Traditional quantifiers combine ordinary language generality and ontology assumptions [Harré] |
| 9991 | For Frege the variable ranges over all objects [Frege, by Tait] |
| 10536 | Frege's domain for variables is all objects, but modern interpretations first fix the domain [Dummett on Frege] |
| 7730 | Frege introduced quantifiers for generality [Frege, by Weiner] |
| 7742 | Frege reduced most quantifiers to 'everything' combined with 'not' [Frege, by McCullogh] |
| 15878 | Some quantifiers, such as 'any', rule out any notion of order within their range [Harré] |
| 13824 | Proof theory began with Frege's definition of derivability [Frege, by Prawitz] |
| 13609 | Frege produced axioms for logic, though that does not now seem the natural basis for logic [Frege, by Kaplan] |
| 13002 | It is always good to reduce the number of axioms [Leibniz] |
| 13008 | Geometry, unlike sensation, lets us glimpse eternal truths and their necessity [Leibniz] |
| 12956 | Only whole numbers are multitudes of units [Leibniz] |
| 12937 | We shouldn't just accept Euclid's axioms, but try to demonstrate them [Leibniz] |
| 17855 | It may be possible to define induction in terms of the ancestral relation [Frege, by Wright,C] |
| 10607 | Frege's logic has a hierarchy of object, property, property-of-property etc. [Frege, by Smith,P] |
| 11008 | Existence is not a first-order property, but the instantiation of a property [Frege, by Read] |
| 12932 | The idea of being must come from our own existence [Leibniz] |
| 12966 | Objects of ideas can be divided into abstract and concrete, and then further subdivided [Leibniz] |
| 12993 | Have five categories - substance, quantity, quality, action/passion, relation - and their combinations [Leibniz] |
| 12989 | Our true divisions of nature match reality, but are probably incomplete [Leibniz] |
| 15874 | Scientific properties are not observed qualities, but the dispositions which create them [Harré] |
| 12959 | We discern active power from our minds, so mind must be involved in all active powers [Leibniz] |
| 12967 | I use the word 'entelechy' for a power, to include endeavour, as well as mere aptitude [Leibniz] |
| 12965 | All occurrence in the depth of a substance is spontaneous 'action' [Leibniz] |
| 12999 | Substances are primary powers; their ways of being are the derivative powers [Leibniz] |
| 5056 | Material or immaterial substances cannot be conceived without their essential activity [Leibniz] |
| 12969 | The active powers which are not essential to the substance are the 'real qualities' [Leibniz] |
| 12941 | There cannot be power without action; the power is a disposition to act [Leibniz] |
| 12990 | Real (non-logical) abstract terms are either essences or accidents [Leibniz] |
| 12939 | Wholly uniform things like space and numbers are mere abstractions [Leibniz] |
| 12979 | The only way we can determine individuals is by keeping hold of them [Leibniz] |
| 12971 | If two individuals could be indistinguishable, there could be no principle of individuation [Leibniz] |
| 13098 | We use things to distinguish places and times, not vice versa [Leibniz] |
| 13075 | No two things are quite the same, so there must be an internal principle of distinction [Leibniz] |
| 12953 | Fluidity is basic, and we divide into bodies according to our needs [Leibniz] |
| 12943 | Individuality is in the bond substance gives between past and future [Leibniz] |
| 11855 | Substances cannot be bare, but have activity as their essence [Leibniz] |
| 12970 | We can imagine two bodies interpenetrating, as two rays of light seem to [Leibniz] |
| 12986 | The essence of baldness is vague and imperfect [Leibniz] |
| 12968 | A 'substratum' is just a metaphor for whatever supports several predicates [Leibniz] |
| 12931 | Particular truths are just instances of general truths [Leibniz] |
| 12811 | We can't know individuals, or determine their exact individuality [Leibniz] |
| 12981 | Essence is just the possibility of a thing [Leibniz] |
| 5057 | If you fully understand a subject and its qualities, you see how the second derive from the first [Leibniz] |
| 12987 | For some sorts, a member of it is necessarily a member [Leibniz] |
| 12884 | The same whole ceases to exist if a part is lost [Leibniz] |
| 12975 | We have a distinct idea of gold, to define it, but not a perfect idea, to understand it [Leibniz] |
| 12805 | If two people apply a single term to different resemblances, they refer to two different things [Leibniz] |
| 12806 | Locke needs many instances to show a natural kind, but why not a single instance? [Leibniz, by Jolley] |
| 12972 | Bodies, like Theseus's ship, are only the same in appearance, and never strictly the same [Leibniz] |
| 5055 | No two things are totally identical [Leibniz] |
| 15884 | Laws of nature remain the same through any conditions, if the underlying mechanisms are unchanged [Harré] |
| 12978 | A perfect idea of an object shows that the object is possible [Leibniz] |
| 17079 | Proofs of necessity come from the understanding, where they have their source [Leibniz] |
| 12998 | Understanding grasps the agreements and disagreements of ideas [Leibniz] |
| 12960 | We understand things when they are distinct, and we can derive necessities from them [Leibniz] |
| 13006 | Certainty is where practical doubt is insane, or at least blameworthy [Leibniz] |
| 12996 | I know more than I think, since I know I think A then B then C [Leibniz] |
| 13003 | The Cogito doesn't prove existence, because 'I am thinking' already includes 'I am' [Leibniz] |
| 21253 | Descartes needs to demonstrate how other people can attain his clear and distinct conceptions [Leibniz] |
| 12933 | Arithmetic and geometry are implicitly innate, awaiting revelation [Leibniz] |
| 12991 | Children learn language fast, with little instruction and few definitions [Leibniz] |
| 12929 | All of our thoughts come from within the soul, and not from the senses [Leibniz] |
| 12940 | What is left of the 'blank page' if you remove the ideas? [Leibniz] |
| 19358 | Colour and pain must express the nature of their stimuli, without exact resemblance [Leibniz] |
| 12948 | A pain doesn't resemble the movement of a pin, but it resembles the bodily movement pins cause [Leibniz] |
| 13005 | Truth arises among sensations from grounding reasons and from regularities [Leibniz] |
| 12947 | We only believe in sensible things when reason helps the senses [Leibniz] |
| 4302 | You may experience a universal truth, but only reason can tell you that it is always true [Leibniz] |
| 12930 | The senses are confused, and necessities come from distinct intellectual ideas [Leibniz] |
| 13001 | Our sensation of green is a confused idea, like objects blurred by movement [Leibniz] |
| 12949 | Light takes time to reach us, so objects we see may now not exist [Leibniz] |
| 15880 | In physical sciences particular observations are ordered, but in biology only the classes are ordered [Harré] |
| 15869 | Reports of experiments eliminate the experimenter, and present results as the behaviour of nature [Harré] |
| 15881 | We can save laws from counter-instances by treating the latter as analytic definitions [Harré] |
| 15882 | Since there are three different dimensions for generalising laws, no one system of logic can cover them [Harré] |
| 5053 | The instances confirming a general truth are never enough to establish its necessity [Leibniz] |
| 15888 | The grue problem shows that natural kinds are central to science [Harré] |
| 15887 | 'Grue' introduces a new causal hypothesis - that emeralds can change colour [Harré] |
| 15889 | It is because ravens are birds that their species and their colour might be connected [Harré] |
| 15890 | Non-black non-ravens just aren't part of the presuppositions of 'all ravens are black' [Harré] |
| 15885 | The necessity of Newton's First Law derives from the nature of material things, not from a mechanism [Harré] |
| 12977 | We will only connect our various definitions of gold when we understand it more deeply [Leibniz] |
| 5054 | Animal thought is a shadow of reasoning, connecting sequences of images by imagination [Leibniz] |
| 12944 | It is a serious mistake to think that we are aware of all of our perceptions [Leibniz] |
| 12951 | Abstraction attends to the general, not the particular, and involves universal truths [Leibniz] |
| 15868 | Idealisation idealises all of a thing's properties, but abstraction leaves some of them out [Harré] |
| 19364 | Volition automatically endeavours to move towards what it sees as good (and away from bad) [Leibniz] |
| 12942 | Memory doesn't make identity; a man who relearned everything would still be the same man [Leibniz] |
| 12973 | We know our own identity by psychological continuity, even if there are some gaps [Leibniz] |
| 19368 | The will determines action, by what is seen as good, but it does not necessitate it [Leibniz] |
| 12935 | Every feeling is the perception of a truth [Leibniz] |
| 12938 | An idea is an independent inner object, which expresses the qualities of things [Leibniz] |
| 12945 | Thoughts correspond to sensations, but ideas are independent of thoughts [Leibniz] |
| 12950 | We must distinguish images from exact defined ideas [Leibniz] |
| 19357 | The idea of green seems simple, but it must be compounded of the ideas of blue and yellow [Leibniz] |
| 12995 | The name 'gold' means what we know of gold, and also further facts about it which only others know [Leibniz] |
| 12807 | The word 'gold' means a hidden constitution known to experts, and not just its appearances [Leibniz] |
| 22280 | Frege's account was top-down and decompositional, not bottom-up and compositional [Frege, by Potter] |
| 12946 | The idea of the will includes the understanding [Leibniz] |
| 12964 | If would be absurd not to disagree with someone's taste if it was a taste for poisons [Leibniz] |
| 12958 | Love is pleasure in the perfection, well-being or happiness of its object [Leibniz] |
| 12957 | The good is the virtuous, the pleasing, or the useful [Leibniz] |
| 12962 | Pleasure is a sense of perfection [Leibniz] |
| 12934 | We can't want everyone to have more than their share, so a further standard is needed [Leibniz] |
| 12936 | There are natural rewards and punishments, like illness after over-indulgence [Leibniz] |
| 15886 | Science rests on the principle that nature is a hierarchy of natural kinds [Harré] |
| 15864 | Classification is just as important as laws in natural science [Harré] |
| 15865 | Newton's First Law cannot be demonstrated experimentally, as that needs absence of external forces [Harré] |
| 15862 | Laws can come from data, from theory, from imagination and concepts, or from procedures [Harré] |
| 15870 | Are laws of nature about events, or types and universals, or dispositions, or all three? [Harré] |
| 15871 | Are laws about what has or might happen, or do they also cover all the possibilities? [Harré] |
| 15876 | Maybe laws of nature are just relations between properties? [Harré] |
| 15860 | We take it that only necessary happenings could be laws [Harré] |
| 15867 | Laws describe abstract idealisations, not the actual mess of nature [Harré] |
| 15872 | Must laws of nature be universal, or could they be local? [Harré] |
| 11856 | Qualities should be predictable from the nature of the subject [Leibniz] |
| 12994 | Gold has a real essence, unknown to us, which produces its properties [Leibniz] |
| 12808 | Part of our idea of gold is its real essence, which is not known to us in detail [Leibniz] |
| 15892 | Laws of nature state necessary connections of things, events and properties, based on models of mechanisms [Harré] |
| 15875 | In counterfactuals we keep substances constant, and imagine new situations for them [Harré] |
| 12985 | Maybe motion is definable as 'change of place' [Leibniz] |
| 12952 | Space is an order among actual and possible things [Leibniz] |
| 12955 | If there were duration without change, we could never establish its length [Leibniz] |
| 12954 | God's essence is the source of possibilities, and his will the source of existents [Leibniz] |
| 12988 | The universe contains everything possible for its perfect harmony [Leibniz] |
| 1414 | A perfection is a simple quality, which is positive and absolute, and has no limit [Leibniz] |
| 21252 | Perfections must have overlapping parts if their incompatibility is to be proved [Leibniz] |
| 19328 | Without the principle of sufficient reason, God's existence could not be demonstrated [Leibniz] |
| 7741 | The predicate 'exists' is actually a natural language expression for a quantifier [Frege, by Weiner] |
| 5058 | Animals have thought and sensation, and indestructible immaterial souls [Leibniz] |