44 ideas
| 23250 | Desired responsible actions result either from rational or from irrational desire [Aristotle] |
| 5847 | It is the role of dialectic to survey syllogisms [Aristotle] |
| 5784 | In its primary and formal sense, 'true' applies to propositions, not beliefs [Russell] |
| 5777 | The truth or falsehood of a belief depends upon a fact to which the belief 'refers' [Russell] |
| 5783 | Propositions of existence, generalities, disjunctions and hypotheticals make correspondence tricky [Russell] |
| 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] |
| 10894 | A sentence-set is 'satisfiable' if at least one truth-assignment makes them all true [Zalabardo] |
| 10901 | Some formulas are 'satisfiable' if there is a structure and interpretation that makes them 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] |
| 5780 | The three questions about belief are its contents, its success, and its character [Russell] |
| 5862 | A single counterexample is enough to prove that a truth is not necessary [Aristotle] |
| 5854 | Nobody fears a disease which nobody has yet caught [Aristotle] |
| 5778 | If we object to all data which is 'introspective' we will cease to believe in toothaches [Russell] |
| 5779 | There are distinct sets of psychological and physical causal laws [Russell] |
| 5781 | Our important beliefs all, if put into words, take the form of propositions [Russell] |
| 5782 | A proposition expressed in words is a 'word-proposition', and one of images an 'image-proposition' [Russell] |
| 5776 | A proposition is what we believe when we believe truly or falsely [Russell] |
| 5849 | Rhetoric is a political offshoot of dialectic and ethics [Aristotle] |
| 5851 | Pentathletes look the most beautiful, because they combine speed and strength [Aristotle] |
| 5858 | Men are physically prime at thirty-five, and mentally prime at forty-nine [Aristotle] |
| 5855 | We all feel universal right and wrong, independent of any community or contracts [Aristotle] |
| 5850 | Happiness is composed of a catalogue of internal and external benefits [Aristotle] |
| 5856 | Self-interest is a relative good, but nobility an absolute good [Aristotle] |
| 5853 | The best virtues are the most useful to others [Aristotle] |
| 5848 | All good things can be misused, except virtue [Aristotle] |
| 5857 | The young feel pity from philanthropy, but the old from self-concern [Aristotle] |
| 5859 | Rich people are mindlessly happy [Aristotle] |
| 5852 | The four constitutions are democracy (freedom), oligarchy (wealth), aristocracy (custom), tyranny (security) [Aristotle] |
| 1660 | It is noble to avenge oneself on one's enemies, and not come to terms with them [Aristotle] |
| 5861 | People assume events cause what follows them [Aristotle] |