From: Brian Holtz [brian@holtz.org]
Sent: Tuesday, February 19, 2002 11:10 AM
To: alt.atheism.moderated
Subject: Re: Are irrational numbers supernatural?

"Paul Holbach" <heir-of-holbach@freenet.de> wrote 

> > You seem to be confusing two different senses of 'knowable': 
> > 1) recognizable/definable, and 2) known to be existent.
> > There are many things we know that we cannot know. [..]
> > I know that I cannot know about any event whose light
> > cone I am not in. [..]
> 
> There are three types of knowledge:
> 1) Knowledge of particular/individual objects: knowledge of "things".
> 2) Knowledge of universals/names: knowledge of concepts/words   
> (linguistic competence)
> 3) Knowledge of  truths/facts: propositional knowledge.

These are indeed three different kinds of knowables 
(i.e. objects of knowledge), but I still don't know precisely
what you mean by "unknowable".

> Is there an X that makes "X is unknowable" a true proposition?
> regarding 1) No!

I agree that "X is not definable" cannot be true for any 
proper name X, since to be a name is to have an (intensional 
or extensional) definition.

I do not agree that "X cannot be known to exist" is false
for any proper name X, since it would be true for
the proper name of anything we know does not exist. If
we know "Sherlock Holmes does not exist", then it is true
that "Sherlock Holmes cannot be known to exist".

I do not agree that "X is not recognizable" cannot be true for
any proper name X.

> regarding 2) No! In order for any concept to be a concept at all,
> there must be a linguistic community sharing a semantic code that
> (pre-)defines its scope of meaning. So concepts are always knowable.

I agree that "X is not definable" cannot be true for any concept X.

I do not agree that "X cannot be known to exist" is false for
any concept X. One example is my hypothetical Santa Claus who
covers his tracks to make everyone think he is a childrens' myth.

I do not agree that "X is not recognizable" cannot be true
for any concept X.

> regarding 3) Yes!

Right, as my examples demonstrated.

> eg (X="that there are more than the four dimensions of spacetime" is
> unknowable) is true!

String theorists would disagree. 

> (X="that I cannot know about any event whose light cone I am not in"
> is unknowable) is false

I didn't say it wasn't.

-- 
brian@holtz.org
http://humanknowledge.net