35 ideas
| 14052 | Begin philosophy when you are young, and keep going when you are old [Epicurus] |
| 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] |
| 10893 | Γ |= φ for sentences if φ is true when all of Γ is true [Zalabardo] |
| 10899 | Γ |= φ if φ is true when all of Γ is true, for all structures and interpretations [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] |
| 10895 | 'Logically true' (|= φ) is true for every truth-assignment [Zalabardo] |
| 10900 | Logically true sentences are true in all structures [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] |
| 10891 | If a set is defined by induction, then proof by induction can be applied to it [Zalabardo] |
| 14062 | Sooner follow mythology, than accept the 'fate' of natural philosophers [Epicurus] |
| 1837 | We should not refer things to irresponsible necessity, but either to fortune or to our own will [Epicurus] |
| 1836 | Prudence is more valuable than philosophy, because it avoids confusions of the soul [Epicurus] |
| 14061 | Our own choices are autonomous, and the basis for praise and blame [Epicurus] |
| 14055 | The wisdom that produces a good life also produces a good death [Epicurus] |
| 14054 | Fearing death is absurd, because we are not present when it occurs [Epicurus] |
| 14053 | It is absurd to fear the pain of death when you are not even facing it [Epicurus] |
| 1833 | Pleasure is the first good in life [Epicurus] |
| 14058 | Pleasure is the goal, but as lack of pain and calm mind, not as depraved or greedy pleasure [Epicurus] |
| 14057 | All pleasures are good, but it is not always right to choose them [Epicurus] |
| 22457 | If the aim is good outcomes, why are killings worse than deaths? [Scheffler, by Foot] |
| 14063 | Sooner a good decision going wrong, than a bad one turning out for the good [Epicurus] |
| 14059 | The best life is not sensuality, but rational choice and healthy opinion [Epicurus] |
| 1835 | True pleasure is not debauchery, but freedom from physical and mental pain [Epicurus] |
| 14056 | We only need pleasure when we have the pain of desire [Epicurus] |
| 14060 | Prudence is the greatest good, and more valuable than philosophy, because it produces virtue [Epicurus] |