From: pjnelson@uxa.cso.uiuc.edu (nelson peter j)
Subject: Re: Certainty, Sureness, Knowledge, Proof (Was:Re: Strong vs. Weak atheism
Organization: University of Illinois at Urbana
Date: Wed, 16 Dec 1992 23:51:50 GMT

>>This is how I decide, as an Objectivist...
>>
>>"Idea X is 'certain' if, in a given context of knowledge, the evidence
>>for X is _conclusive_.

>This sounds circular.  You could just as easily say,
>"idea X is conclusive if, in a given context, the evidence
>for X is certain".

Don't take things out of context! Besides, "certain" refers to an idea,
"conclusive" describes evidence. Blame the English language for having
so many words. :-)

>>In such a context, all the evidence supports X
>>and there is no evidence to support any alternative...

There is the definition of "conclusive" evidence, which in turn,
will show that idea X is "certain".

>Except for certain axiomatic systems, like geometry,
>this 100% vs 0% exclusivity rarely happens.

Do you want everything to be "certain"? :-)

>> "You cannot challenge a claim to certainty by means of an _arbitrary_ 
>>declaration of a counter-possibility,...you cannot manufacture 
>>possibilities without evidence..."
>>			   Leonard Peikoff (Ayn Rand's Intellectual Heir)
>>			   "The Philosophy of Objectivism" lecture series

>Sure you can.  Many scientific advances were, at one time,
>"possibilities without evidence".  The process of obtaining
>evidence, and refining and restricting the possibilities,
>is what scientific research does.

The phrase "arbitrary claims" refers to claims such as the existence of
"God" or "Invisible Pink Unicorns". It's simply saying that someone can't
invent (im)possibilities to prove a point. Trying to obtain *evidence*
to prove a point IS valid. 

>>Since there is no proof that God exists, I am certain that God does not exist.

>Using this idea, the statement, "since there is no proof that
>black holes exist, I am certain that black holes do not exist"
>would have been correct, until recently.  
>Black holes were theoretical constructs
>(ie., possibility without evidence) which were allowed and/or
>demanded by certain cosmological systems.  This "certainty"
>is overturned with better observations.

Exactly. The definition of "certainty" at the top of the post uses
the phrase "in a given context of knowledge". As I point out below,
knowledge is contextual. 

>Certainty is an emotion.  You have nicely described the conditions
>under which you feel certain.  Out christian buddies have other
>criteria for certainty, usually subjective experience or an
>appeal to tradition.  Neither experience of certainty says
>anything about the existence of God.

In my definition, "certainty" is an objective conclusion based on
the evidence presented to me. It was NOT defined as an emotion.

>>PS: "I 'know' that God does not exist" implies that, based on my current
>>    knowledge, God does not exist. Knowledge is contextual, and could
>>    change based on future evidence.

>True.  However, I've found that feelings of certainty result in
>a tendency to overlook or distort new evidence.  This is why
>I don't bother with it.  One aspect of "maturity"
>and "wisdom" is the ability to function and prosper in the
>face of continual uncertainty and ambiguity.

I agree, but my original posting was an attempt to dispell the common
belief that being "certain" or claiming to "know" are absolutes.
Man is not omnipotent, but he can "know" and be "certain".

>>    People who claim "to know" is an
>>    absolute that will never change are apparantly Omnipotent.

>Nope, just certain.  :)

>>Peter J Nelson
>| Eric |         --- Keep "Saturn" in "Saturnalia" ---
Peter J Nelson
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