Monday, March 12, 2012

Stromboli and flying horses

I replied to this Maverick post, but will copy it here as well.  Maverick says that the following argument is valid but not sound:

Pegasus exists.
Pegasus is a flying horse.
A flying horse exists.

And he claims that the first premise [Pegasus exists], though false, is needed for the argument to be valid. Do I agree?  Certainly not. On my view, which is not a standard view, 'Pegasus is a flying horse' has two meanings, a literal and a non-literal. The literal meaning is such that its truth implies that something is a flying horse. I also hold the Brentano-Quine view that 'something' is always 'existing something'. Thus the argument is valid with the second premise alone. "Pegasus is a flying horse" is equivalent (literally understood) to "Something is Pegasus and it is a flying horse" which implies "something is a flying horse" without the help of the first existential premise.  Literally understood, "A is B" is always existential. 

The second meaning, the non-literal one, is 'In Greek mythology, Pegasus is a flying horse', which means the same as 'Greek mythology says that Pegasus is a flying horse'. This is not existential, at least in respect of the that-clause.  It can be true that I say that some horses fly, even though it is false that any horse flies (as far as I know).  Thus, on this non-literal interpretation, Bill's argument is not valid, for it really reads:

Pegasus exists.
Greek mythology says that Pegasus is a flying horse
A flying horse exists.

which is not valid. At most, it would imply 'some [existing] creature is said by Greek mythology to be a flying horse'.

This is not a standard view, of course. The standard view would be that 'Pegasus' is meaningless because it fails to refer. Therefore Bill's argument is invalid anyway.


David Brightly said...

Ed, in your final comment at BV's you say

>> 2. something is an island volcano. Therefore an island volcano exists

is valid only on the Brentano ('Quine') interpretation of 'exists'. <<

This seems to say that one could reject Brentano-Quine and hold that something is an island volcano could be true yet an island volcano exists be false. This stretches my understanding of something is a ... and a ... exists. Can you elaborate?

Edward Ockham said...


1. "Something is a nonexistent island volcano, therefore some island volcano exists"

is no more valid than

2. "Something is a nonwhite island volcano, therefore some island volcano is white"

David Brightly said...

Sorry Ed, but you have lost me completely. Two objections:

a) 'something is a nonexistent island volcano' is false (nothing is a nonexistent anything), 'some island volcano exists' is true, so interpreting 'therefore' as implication at least makes (1) true.

b) the analogy between (1) and (2) requires that 'exists' be seen as an ordinary predicate. Is this one of your presuppositions?

Do you perhaps see 'something' ranging over terms rather than objects?

To convince me that 'something' and 'exists' can come apart you'll have to give me a possible world in which 'something is an island volcano' is true yet 'an island volcano exists' is false. That's a reasonable request, surely?

Edward Ockham said...

The problem is that I don't think they can come apart. I am playing Devil's advocate to a theory that doesn't make much sense to me. Where is Bill when you need him?