more on this theme     |     more from this thinker


Single Idea 10283

[filed under theme 5. Theory of Logic / I. Semantics of Logic / 1. Semantics of Logic ]

Full Idea

To have a truth-value, a first-order formula needs an 'interpretation' (I) of its constants, and a 'valuation' (ν) of its variables. Something in the world is attached to the constants; objects are attached to variables.

Gist of Idea

A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables

Source

Wilfrid Hodges (First-Order Logic [2001], 1.3)

Book Ref

'Blackwell Guide to Philosophical Logic', ed/tr. Goble,Lou [Blackwell 2001], p.13


The 8 ideas from 'First-Order Logic'

Logic is the study of sound argument, or of certain artificial languages (or applying the latter to the former) [Hodges,W]
Down Löwenheim-Skolem: if a countable language has a consistent theory, that has a countable model [Hodges,W]
Up Löwenheim-Skolem: if infinite models, then arbitrarily large models [Hodges,W]
If a first-order theory entails a sentence, there is a finite subset of the theory which entails it [Hodges,W]
A formula needs an 'interpretation' of its constants, and a 'valuation' of its variables [Hodges,W]
There are three different standard presentations of semantics [Hodges,W]
I |= φ means that the formula φ is true in the interpretation I [Hodges,W]
A 'set' is a mathematically well-behaved class [Hodges,W]