27 ideas
10688 | 'Equivocation' is when terms do not mean the same thing in premises and conclusion [Beall/Restall] |
10147 | The Axiom of Choice is consistent with the other axioms of set theory [Feferman/Feferman] |
10148 | Axiom of Choice: a set exists which chooses just one element each of any set of sets [Feferman/Feferman] |
10149 | Platonist will accept the Axiom of Choice, but others want criteria of selection or definition [Feferman/Feferman] |
10150 | The Trichotomy Principle is equivalent to the Axiom of Choice [Feferman/Feferman] |
10146 | Cantor's theories needed the Axiom of Choice, but it has led to great controversy [Feferman/Feferman] |
10690 | Formal logic is invariant under permutations, or devoid of content, or gives the norms for thought [Beall/Restall] |
10691 | Logical consequence needs either proofs, or absence of counterexamples [Beall/Restall] |
10695 | Logical consequence is either necessary truth preservation, or preservation based on interpretation [Beall/Restall] |
10689 | A step is a 'material consequence' if we need contents as well as form [Beall/Restall] |
10696 | A 'logical truth' (or 'tautology', or 'theorem') follows from empty premises [Beall/Restall] |
10158 | A structure is a 'model' when the axioms are true. So which of the structures are models? [Feferman/Feferman] |
10162 | Tarski and Vaught established the equivalence relations between first-order structures [Feferman/Feferman] |
10693 | Models are mathematical structures which interpret the non-logical primitives [Beall/Restall] |
10159 | Löwenheim-Skolem Theorem, and Gödel's completeness of first-order logic, the earliest model theory [Feferman/Feferman] |
10160 | Löwenheim-Skolem says if the sentences are countable, so is the model [Feferman/Feferman] |
10161 | If a sentence holds in every model of a theory, then it is logically derivable from the theory [Feferman/Feferman] |
10156 | 'Recursion theory' concerns what can be solved by computing machines [Feferman/Feferman] |
10155 | Both Principia Mathematica and Peano Arithmetic are undecidable [Feferman/Feferman] |
10692 | Hilbert proofs have simple rules and complex axioms, and natural deduction is the opposite [Beall/Restall] |
14664 | Necessary beings (numbers, properties, sets, propositions, states of affairs, God) exist in all possible worlds [Plantinga] |
14666 | Socrates is a contingent being, but his essence is not; without Socrates, his essence is unexemplified [Plantinga] |
14662 | Possible worlds clarify possibility, propositions, properties, sets, counterfacts, time, determinism etc. [Plantinga] |
16472 | Plantinga's actualism is nominal, because he fills actuality with possibilia [Stalnaker on Plantinga] |
16469 | Plantinga has domains of sets of essences, variables denoting essences, and predicates as functions [Plantinga, by Stalnaker] |
16470 | Plantinga's essences have their own properties - so will have essences, giving a hierarchy [Stalnaker on Plantinga] |
14663 | Are propositions and states of affairs two separate things, or only one? I incline to say one [Plantinga] |