49 ideas
354 | Wisdom makes virtue and true goodness possible [Plato] |
370 | Philosophy is a purification of the soul ready for the afterlife [Plato] |
350 | In investigation the body leads us astray, but the soul gets a clear view of the facts [Plato] |
362 | The greatest misfortune for a person is to develop a dislike for argument [Plato] |
10888 | Sets can be defined by 'enumeration', or by 'abstraction' (based on a property) [Zalabardo] |
10889 | The 'Cartesian Product' of two sets relates them by pairing every element with every element [Zalabardo] |
10890 | A 'partial ordering' is reflexive, antisymmetric and transitive [Zalabardo] |
10886 | Determinacy: an object is either in a set, or it isn't [Zalabardo] |
10887 | Specification: Determinate totals of objects always make a set [Zalabardo] |
10897 | A first-order 'sentence' is a formula with no free variables [Zalabardo] |
10899 | Γ |= φ if φ is true when all of Γ is true, for all structures and interpretations [Zalabardo] |
10893 | Γ |= φ for sentences if φ is true when all of Γ is true [Zalabardo] |
10896 | Propositional logic just needs ¬, and one of ∧, ∨ and → [Zalabardo] |
10898 | The semantics shows how truth values depend on instantiations of properties and relations [Zalabardo] |
10902 | We can do semantics by looking at given propositions, or by building new ones [Zalabardo] |
10892 | We make a truth assignment to T and F, which may be true and false, but merely differ from one another [Zalabardo] |
10900 | Logically true sentences are true in all structures [Zalabardo] |
10895 | 'Logically true' (|= φ) is true for every truth-assignment [Zalabardo] |
10901 | Some formulas are 'satisfiable' if there is a structure and interpretation that makes them true [Zalabardo] |
10894 | A sentence-set is 'satisfiable' if at least one truth-assignment makes them all true [Zalabardo] |
10903 | A structure models a sentence if it is true in the model, and a set of sentences if they are all true in the model [Zalabardo] |
13155 | If you add one to one, which one becomes two, or do they both become two? [Plato] |
10891 | If a set is defined by induction, then proof by induction can be applied to it [Zalabardo] |
21347 | If Simmias is taller than Socrates, that isn't a feature that is just in Simmias [Plato] |
360 | We must have a prior knowledge of equality, if we see 'equal' things and realise they fall short of it [Plato] |
1 | There is only one source for all beauty [Plato] |
368 | Other things are named after the Forms because they participate in them [Plato] |
16516 | The ship which Theseus took to Crete is now sent to Delos crowned with flowers [Plato] |
359 | If we feel the inadequacy of a resemblance, we must recollect the original [Plato] |
357 | People are obviously recollecting when they react to a geometrical diagram [Plato] |
9343 | To achieve pure knowledge, we must get rid of the body and contemplate things with the soul [Plato] |
15859 | To investigate the causes of things, study what is best for them [Plato] |
13154 | Do we think and experience with blood, air or fire, or could it be our brain? [Plato] |
364 | One soul can't be more or less of a soul than another [Plato] |
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] |
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] |
2711 | Prescriptivism implies a commitment, but descriptivism doesn't [Hare] |
2709 | Prescriptivism sees 'ought' statements as imperatives which are universalisable [Hare] |
361 | It is a mistake to think that the most violent pleasure or pain is therefore the truest reality [Plato] |
351 | War aims at the acquisition of wealth, because we are enslaved to the body [Plato] |
2710 | Moral judgements must invoke some sort of principle [Hare] |
13156 | Fancy being unable to distinguish a cause from its necessary background conditions! [Plato] |
369 | If the Earth is spherical and in the centre, it is kept in place by universal symmetry, not by force [Plato] |
363 | Whether the soul pre-exists our body depends on whether it contains the ultimate standard of reality [Plato] |