[FOM] A minor issue in modal logic

Richard Heck rgheck at brown.edu
Wed Jul 7 17:11:27 EDT 2010

On 07/07/2010 04:52 PM, laureano luna wrote:
> Richard Heck also wrote:
> "What is more important is to distinguish (in this notation) "Np[a]" from
> "N(p[a])". I.e.
>       It is true at a that it is necessary that p
> from
>       It is necessary that p is true at a.
> The former trivially entails Np, if a is actual; I took the question to
> concern the latter, which does not entail Np."
> I think your reading is less straightforward. The original wording is:
> ""Np[a]" means "p is necessarily true in the actual world"".
> I take it that 'necessarily true' and 'necessary' are synonymous.
Of course. But it's matter of
     p is, necessarily, true-in-the-actual-world
     p is necessarily-true (in the actual world)
The latter, as you say, is essentially redundant and makes the question 
being asked trivial (or even confused). The former leads to interesting 
questions about the logic of actually and, as I read the original post, 
about the argument being considered.


Richard G Heck Jr
Romeo Elton Professor of Natural Theology
Brown University

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