49 ideas
| 9724 | Until the 1960s the only semantics was truth-tables [Enderton] |
| 9703 | 'dom R' indicates the 'domain' of objects having a relation [Enderton] |
| 9705 | 'fld R' indicates the 'field' of all objects in the relation [Enderton] |
| 9704 | 'ran R' indicates the 'range' of objects being related to [Enderton] |
| 9710 | We write F:A→B to indicate that A maps into B (the output of F on A is in B) [Enderton] |
| 9707 | 'F(x)' is the unique value which F assumes for a value of x [Enderton] |
| 9712 | A relation is 'symmetric' on a set if every ordered pair has the relation in both directions [Enderton] |
| 9713 | A relation is 'transitive' if it can be carried over from two ordered pairs to a third [Enderton] |
| 9699 | The 'powerset' of a set is all the subsets of a given set [Enderton] |
| 9700 | Two sets are 'disjoint' iff their intersection is empty [Enderton] |
| 9702 | A 'domain' of a relation is the set of members of ordered pairs in the relation [Enderton] |
| 9701 | A 'relation' is a set of ordered pairs [Enderton] |
| 9706 | A 'function' is a relation in which each object is related to just one other object [Enderton] |
| 9708 | A function 'maps A into B' if the relating things are set A, and the things related to are all in B [Enderton] |
| 9709 | A function 'maps A onto B' if the relating things are set A, and the things related to are set B [Enderton] |
| 9711 | A relation is 'reflexive' on a set if every member bears the relation to itself [Enderton] |
| 9714 | A relation satisfies 'trichotomy' if all pairs are either relations, or contain identical objects [Enderton] |
| 9717 | A set is 'dominated' by another if a one-to-one function maps the first set into a subset of the second [Enderton] |
| 9715 | An 'equivalence relation' is a reflexive, symmetric and transitive binary relation [Enderton] |
| 9716 | We 'partition' a set into distinct subsets, according to each relation on its objects [Enderton] |
| 9722 | Inference not from content, but from the fact that it was said, is 'conversational implicature' [Enderton] |
| 9718 | Validity is either semantic (what preserves truth), or proof-theoretic (following procedures) [Enderton] |
| 9721 | A logical truth or tautology is a logical consequence of the empty set [Enderton] |
| 9994 | A truth assignment to the components of a wff 'satisfy' it if the wff is then True [Enderton] |
| 9719 | A proof theory is 'sound' if its valid inferences entail semantic validity [Enderton] |
| 9720 | A proof theory is 'complete' if semantically valid inferences entail proof-theoretic validity [Enderton] |
| 9995 | Proof in finite subsets is sufficient for proof in an infinite set [Enderton] |
| 9996 | Expressions are 'decidable' if inclusion in them (or not) can be proved [Enderton] |
| 9997 | For a reasonable language, the set of valid wff's can always be enumerated [Enderton] |
| 9723 | Sentences with 'if' are only conditionals if they can read as A-implies-B [Enderton] |
| 3847 | Man is nothing else but the sum of his actions [Sartre] |
| 3846 | Man IS freedom [Sartre] |
| 3843 | There is no human nature [Sartre] |
| 20762 | There are no values to justify us, and no excuses [Sartre] |
| 3852 | If values depend on us, freedom is the foundation of all values [Sartre] |
| 5049 | Intelligent pleasure is the perception of beauty, order and perfection [Leibniz] |
| 20764 | In becoming what we want to be we create what we think man ought to be [Sartre] |
| 3848 | Cowards are responsible for their cowardice [Sartre] |
| 20763 | When my personal freedom becomes involved, I must want freedom for everyone else [Sartre] |
| 22229 | Existentialists says that cowards and heroes make themselves [Sartre] |
| 3842 | Existence before essence (or begin with the subjective) [Sartre] |
| 6868 | 'Existence precedes essence' means we have no pre-existing self, but create it through existence [Sartre, by Le Poidevin] |
| 3844 | Existentialism says man is whatever he makes of himself [Sartre] |
| 20754 | It is dishonest to offer passions as an excuse [Sartre] |
| 6571 | When a man must choose between his mother and the Resistance, no theory can help [Sartre, by Fogelin] |
| 3851 | If I do not choose, that is still a choice [Sartre] |
| 5048 | Perfection is simply quantity of reality [Leibniz] |
| 3845 | Without God there is no intelligibility or value [Sartre] |
| 5050 | Evil serves a greater good, and pain is necessary for higher pleasure [Leibniz] |