Absence of evidence is evidence of absence.
Very often stuff like this happens:
Somebody says "Kim, you are mistaken!", but no valid reasons are given.
Somebody says "God exists", but no valid reasons are given.
Somebody says "People are healed!", but there are no valid healings.
In all these cases, it is correct to become more certain that whatever
it is that is said, is wrong. The lack of evidence confirms that the
saying is wrong.
Many people have an intuitive understanding that this is valid. Many
know that it is valid through experience. Many believe it is pure
nonsense. A few know why it is valid.
I will below give an overview over a proof for the validity of
arguments like this, with Bayesian statistics. (Jump over it if you
Suppose that A <- B
The probability of event A is P(A)
One observes lack of B, that is !B
What is now the probability of A now that we know that B lacks? P( A | !B )
The usual is that P( A | !B ) = P( A & !B ) / ( P( A & !B ) + P( !A & !B ) )
Since A <- B, then P( !A & B ) = 0
which again means that P( !A & !B ) = P(!A) - P( !A & B ) = P(!A) - 0
This results in
P( A | !B ) = P( A & !B ) / ( P( A & !B ) + P(!A) )
( P( A & B ) + P( A & !B ) ) / ( P( A & B ) + P( A & !B ) + P(!A) ) = P(A)
( "</=" is "less or equal" )
The conclusion is:
P( A | !B ) </= P(A)
If one in addition assumes that P(B) > 0, then one gets
P( A | !B ) < P(A)
You who jumped over the math can start reading again here.
Ergo, the conclusion is that every time one do not se it,
then it is more likely to be untrue.
So every time somebody claims that people can levitate, but one do not
see any levitating people, then one shall increase once confidence
that people do not levitate.
And every time one do not see signs of small green men living in the
radiator, then one shall be surer that they do not exist.
And every time one do not see valid evidence of Gods existence,
one shall become surer that God do not exist.
Simply because this is the right way to think, just like 2+2=4.
This is the reason for why people with claims should justify their
cleims themselves. Because if one claims something without evidence,
that is evidence of being wrong.