71 ideas
19579 | The history of philosophy is just experiments in how to do philosophy [Novalis] |
19583 | Philosophy only begins when it studies itself [Novalis] |
22026 | Philosophy is homesickness - the urge to be at home everywhere [Novalis] |
19588 | The highest aim of philosophy is to combine all philosophies into a unity [Novalis] |
19598 | Philosophy relies on our whole system of learning, and can thus never be complete [Novalis] |
19586 | Philosophers feed on problems, hoping they are digestible, and spiced with paradox [Novalis] |
19587 | Philosophy aims to produce a priori an absolute and artistic world system [Novalis] |
19574 | If man sacrifices truth he sacrifices himself, by acting against his own convictions [Novalis] |
19571 | Delusion and truth differ in their life functions [Novalis] |
9724 | Until the 1960s the only semantics was truth-tables [Enderton] |
9703 | 'dom R' indicates the 'domain' of objects having a relation [Enderton] |
9704 | 'ran R' indicates the 'range' of objects being related to [Enderton] |
9705 | 'fld R' indicates the 'field' of all objects in the relation [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] |
13201 | ∈ says the whole set is in the other; ⊆ says the members of the subset are in the other [Enderton] |
9711 | A relation is 'reflexive' on a set if every member bears the relation to itself [Enderton] |
13204 | The 'ordered pair' <x,y> is defined to be {{x}, {x,y}} [Enderton] |
13206 | A 'linear or total ordering' must be transitive and satisfy trichotomy [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] |
9713 | A relation is 'transitive' if it can be carried over from two ordered pairs to a third [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] |
9712 | A relation is 'symmetric' on a set if every ordered pair has the relation in both directions [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] |
13200 | Note that {Φ} =/= Φ, because Φ ∈ {Φ} but Φ ∉ Φ [Enderton] |
13199 | The empty set may look pointless, but many sets can be constructed from it [Enderton] |
13203 | The singleton is defined using the pairing axiom (as {x,x}) [Enderton] |
9716 | We 'partition' a set into distinct subsets, according to each relation on its objects [Enderton] |
9715 | An 'equivalence relation' is a reflexive, symmetric and transitive binary relation [Enderton] |
13202 | Fraenkel added Replacement, to give a theory of ordinal numbers [Enderton] |
13205 | We can only define functions if Choice tells us which items are involved [Enderton] |
9722 | Inference not from content, but from the fact that it was said, is 'conversational implicature' [Enderton] |
19597 | Logic (the theory of relations) should be applied to mathematics [Novalis] |
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] |
19581 | A problem is a solid mass, which the mind must break up [Novalis] |
19584 | Whoever first counted to two must have seen the possibility of infinite counting [Novalis] |
22025 | Novalis thought self-consciousness cannot disclose 'being', because we are temporal creatures [Novalis, by Pinkard] |
19575 | Refinement of senses increasingly distinguishes individuals [Novalis] |
9723 | Sentences with 'if' are only conditionals if they can read as A-implies-B [Enderton] |
22067 | Poetry is true idealism, and the self-consciousness of the universe [Novalis] |
19572 | Experiences tests reason, and reason tests experience [Novalis] |
19590 | Empiricists are passive thinkers, given their philosophy by the external world and fate [Novalis] |
19594 | General statements about nature are not valid [Novalis] |
19591 | Desire for perfection is an illness, if it turns against what is imperfect [Novalis] |
19596 | The whole body is involved in the formation of thoughts [Novalis] |
19573 | The seat of the soul is where our inner and outer worlds interpenetrate [Novalis] |
19577 | Everything is a chaotic unity, then we abstract, then we reunify the world into a free alliance [Novalis] |
19585 | Every person has his own language [Novalis] |
19578 | Only self-illuminated perfect individuals are beautiful [Novalis] |
19582 | Morality and philosophy are mutually dependent [Novalis] |
22027 | Life isn't given to us like a novel - we write the novel [Novalis] |
19589 | The whole point of a monarch is that we accept them as a higher-born, ideal person [Novalis] |
23053 | The great interest of the human race is cordial unity and unlimited mutual aid [Owen] |
19580 | If the pupil really yearns for the truth, they only need a hint [Novalis] |
19593 | Persons are shaped by a life history; splendid persons are shaped by world history [Novalis] |
19595 | Nature is a whole, and its individual parts cannot be wholly understood [Novalis] |
19592 | The basic relations of nature are musical [Novalis] |
19576 | Religion needs an intermediary, because none of us can connect directly to a godhead [Novalis] |