29 ideas
| 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] |
| 17750 | The first clear proof of the consistency of the first order predicate logic was in 1928 [Hilbert/Ackermann, by Walicki] |
| 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] |
| 13852 | Axioms are ω-incomplete if the instances are all derivable, but the universal quantification isn't [Engelbretsen/Sayward] |
| 16050 | The goodness of a picture supervenes on the picture; duplicates must be equally good [Hare] |
| 2705 | How can intuitionists distinguish universal convictions from local cultural ones? [Hare] |
| 2712 | You can't use intuitions to decide which intuitions you should cultivate [Hare] |
| 2706 | Emotivists mistakenly think all disagreements are about facts, and so there are no moral reasons [Hare] |
| 2708 | An 'ought' statement implies universal application [Hare] |
| 2704 | If morality is just a natural or intuitive description, that leads to relativism [Hare] |
| 2855 | In primary evaluative words like 'ought' prescription is constant but description can vary [Hare, by Hooker,B] |
| 22331 | Moral statements are imperatives rather than the avowals of emotion - but universalisable [Hare, by Glock] |
| 22484 | Universalised prescriptivism could be seen as implying utilitarianism [Hare, by Foot] |
| 4125 | Hare says I acquire an agglomeration of preferences by role-reversal, leading to utilitarianism [Hare, by Williams,B] |
| 4126 | If we have to want the preferences of the many, we have to abandon our own deeply-held views [Williams,B on Hare] |
| 4127 | If morality is to be built on identification with the preferences of others, I must agree with their errors [Williams,B on Hare] |
| 22483 | A judgement is presciptive if we expect it to be acted on [Hare] |
| 2703 | Descriptivism say ethical meaning is just truth-conditions; prescriptivism adds an evaluation [Hare] |
| 2707 | If there can be contradictory prescriptions, then reasoning must be involved [Hare] |
| 2709 | Prescriptivism sees 'ought' statements as imperatives which are universalisable [Hare] |
| 2711 | Prescriptivism implies a commitment, but descriptivism doesn't [Hare] |
| 4360 | By far the easiest way of seeming upright is to be upright [Hare] |
| 2710 | Moral judgements must invoke some sort of principle [Hare] |
| 6449 | The categorical imperative leads to utilitarianism [Hare, by Nagel] |