Combining Philosophers

Ideas for Eubulides, Geoffrey Hellman and Stewart Shapiro

expand these ideas     |    start again     |     choose another area for these philosophers

display all the ideas for this combination of philosophers


16 ideas

5. Theory of Logic / J. Model Theory in Logic / 1. Logical Models
Semantics for models uses set-theory [Shapiro]
The central notion of model theory is the relation of 'satisfaction' [Shapiro]
Model theory deals with relations, reference and extensions [Shapiro]
5. Theory of Logic / J. Model Theory in Logic / 2. Isomorphisms
Categoricity can't be reached in a first-order language [Shapiro]
Theory ontology is never complete, but is only determined 'up to isomorphism' [Shapiro]
The set-theoretical hierarchy contains as many isomorphism types as possible [Shapiro]
An axiomatization is 'categorical' if its models are isomorphic, so there is really only one interpretation [Shapiro]
5. Theory of Logic / J. Model Theory in Logic / 3. Löwenheim-Skolem Theorems
Up Löwenheim-Skolem: if natural numbers satisfy wffs, then an infinite domain satisfies them [Shapiro]
The Löwenheim-Skolem Theorems fail for second-order languages with standard semantics [Shapiro]
Downward Löwenheim-Skolem: each satisfiable countable set always has countable models [Shapiro]
Upward Löwenheim-Skolem: each infinite model has infinite models of all sizes [Shapiro]
The Löwenheim-Skolem theorem seems to be a defect of first-order logic [Shapiro]
The Löwenheim-Skolem theorems show an explosion of infinite models, so 1st-order is useless for infinity [Shapiro]
Substitutional semantics only has countably many terms, so Upward Löwenheim-Skolem trivially fails [Shapiro]
Downward Löwenheim-Skolem: if there's an infinite model, there is a countable model [Shapiro]
Any theory with an infinite model has a model of every infinite cardinality [Shapiro]