48 ideas
22270 | Frege changed philosophy by extending logic's ability to check the grounds of thinking [Potter on Frege] |
8939 | We should not describe human laws of thought, but how to correctly track truth [Frege, by Fisher] |
4971 | I don't use 'subject' and 'predicate' in my way of representing a judgement [Frege] |
17745 | For Frege, 'All A's are B's' means that the concept A implies the concept B [Frege, by Walicki] |
9672 | Free logic is one of the few first-order non-classical logics [Priest,G] |
9697 | X1 x X2 x X3... x Xn indicates the 'cartesian product' of those sets [Priest,G] |
9685 | <a,b&62; is a set whose members occur in the order shown [Priest,G] |
9675 | a ∈ X says a is an object in set X; a ∉ X says a is not in X [Priest,G] |
9674 | {x; A(x)} is a set of objects satisfying the condition A(x) [Priest,G] |
9673 | {a1, a2, ...an} indicates that a set comprising just those objects [Priest,G] |
9677 | Φ indicates the empty set, which has no members [Priest,G] |
9676 | {a} is the 'singleton' set of a (not the object a itself) [Priest,G] |
9679 | X⊂Y means set X is a 'proper subset' of set Y [Priest,G] |
9678 | X⊆Y means set X is a 'subset' of set Y [Priest,G] |
9681 | X = Y means the set X equals the set Y [Priest,G] |
9683 | X ∩ Y indicates the 'intersection' of sets X and Y, the objects which are in both sets [Priest,G] |
9682 | X∪Y indicates the 'union' of all the things in sets X and Y [Priest,G] |
9684 | Y - X is the 'relative complement' of X with respect to Y; the things in Y that are not in X [Priest,G] |
9694 | The 'relative complement' is things in the second set not in the first [Priest,G] |
9693 | The 'intersection' of two sets is a set of the things that are in both sets [Priest,G] |
9692 | The 'union' of two sets is a set containing all the things in either of the sets [Priest,G] |
9698 | The 'induction clause' says complex formulas retain the properties of their basic formulas [Priest,G] |
9688 | A 'singleton' is a set with only one member [Priest,G] |
9687 | A 'member' of a set is one of the objects in the set [Priest,G] |
9695 | An 'ordered pair' (or ordered n-tuple) is a set with its members in a particular order [Priest,G] |
9696 | A 'cartesian product' of sets is the set of all the n-tuples with one member in each of the sets [Priest,G] |
9686 | A 'set' is a collection of objects [Priest,G] |
9689 | The 'empty set' or 'null set' has no members [Priest,G] |
9690 | A set is a 'subset' of another set if all of its members are in that set [Priest,G] |
9691 | A 'proper subset' is smaller than the containing set [Priest,G] |
9680 | The empty set Φ is a subset of every set (including itself) [Priest,G] |
7728 | Frege has a judgement stroke (vertical, asserting or judging) and a content stroke (horizontal, expressing) [Frege, by Weiner] |
16881 | The laws of logic are boundless, so we want the few whose power contains the others [Frege] |
7622 | In 1879 Frege developed second order logic [Frege, by Putnam] |
7729 | Frege replaced Aristotle's subject/predicate form with function/argument form [Frege, by Weiner] |
9950 | A quantifier is a second-level predicate (which explains how it contributes to truth-conditions) [Frege, by George/Velleman] |
9991 | For Frege the variable ranges over all objects [Frege, by Tait] |
10536 | Frege's domain for variables is all objects, but modern interpretations first fix the domain [Dummett on Frege] |
7730 | Frege introduced quantifiers for generality [Frege, by Weiner] |
7742 | Frege reduced most quantifiers to 'everything' combined with 'not' [Frege, by McCullogh] |
13824 | Proof theory began with Frege's definition of derivability [Frege, by Prawitz] |
13609 | Frege produced axioms for logic, though that does not now seem the natural basis for logic [Frege, by Kaplan] |
17855 | It may be possible to define induction in terms of the ancestral relation [Frege, by Wright,C] |
10607 | Frege's logic has a hierarchy of object, property, property-of-property etc. [Frege, by Smith,P] |
11008 | Existence is not a first-order property, but the instantiation of a property [Frege, by Read] |
1556 | By nature people are close to one another, but culture drives them apart [Hippias] |
22280 | Frege's account was top-down and decompositional, not bottom-up and compositional [Frege, by Potter] |
7741 | The predicate 'exists' is actually a natural language expression for a quantifier [Frege, by Weiner] |