more on this theme
|
more from this text
Single Idea 5736
[filed under theme 7. Existence / D. Theories of Reality / 8. Facts / a. Facts
]
Full Idea
Some philosophers say that modal facts cannot be expressed either by name/predicate language, or by first-order predicate calculus, or even by second-order logic.
Clarification
'Modal' facts concern possibility and necessity
Gist of Idea
No sort of plain language or levels of logic can express modal facts properly
Source
Joseph Melia (Modality [2003], Ch.2)
Book Ref
Melia,Joseph: 'Modality' [Acumen 2003], p.21
A Reaction
If 'possible' were a predicate, none of this paraphernalia would be needed. If possible worlds are accepted, then the quantifiers of first-order predicate calculus will do the job. If neither of these will do, there seems to be a problem.
The
17 ideas
from Joseph Melia
|
5732
|
'De re' modality is about things themselves, 'de dicto' modality is about propositions
[Melia]
|
|
5734
|
Possible worlds make it possible to define necessity and counterfactuals without new primitives
[Melia]
|
|
5742
|
In possible worlds semantics the modal operators are treated as quantifiers
[Melia]
|
|
5743
|
If possible worlds semantics is not realist about possible worlds, logic becomes merely formal
[Melia]
|
|
5738
|
We may be sure that P is necessary, but is it necessarily necessary?
[Melia]
|
|
5739
|
Sometimes we want to specify in what ways a thing is possible
[Melia]
|
|
5737
|
Predicate logic has connectives, quantifiers, variables, predicates, equality, names and brackets
[Melia]
|
|
5740
|
Second-order logic needs second-order variables and quantification into predicate position
[Melia]
|
|
5741
|
If every model that makes premises true also makes conclusion true, the argument is valid
[Melia]
|
|
5736
|
No sort of plain language or levels of logic can express modal facts properly
[Melia]
|
|
5735
|
Maybe names and predicates can capture any fact
[Melia]
|
|
5744
|
First-order predicate calculus is extensional logic, but quantified modal logic is intensional (hence dubious)
[Melia]
|
|
5746
|
The Identity of Indiscernibles is contentious for qualities, and trivial for non-qualities
[Melia]
|
|
5748
|
We accept unverifiable propositions because of simplicity, utility, explanation and plausibility
[Melia]
|
|
5749
|
Possible worlds could be real as mathematics, propositions, properties, or like books
[Melia]
|
|
5750
|
Consistency is modal, saying propositions are consistent if they could be true together
[Melia]
|
|
5751
|
The truth of propositions at possible worlds are implied by the world, just as in books
[Melia]
|