Recently, I came across the very relevant statement in a paper I was reading:
“Ignorance cannot support a knowledge claim of any sort except perhaps for the trivial claim that we simply do not know.”
I think this is something we should keep in the front of our minds when we consider those creationist and religious apologetics arguments justifying anti-science positions. You know, Bill Dembski‘s “design filter” – “if we cant show something is caused by chance, or by laws of nature, then it must be intelligently designed.” Or Michael Behe‘s “irreducible complexity” argument. Or the “cosmological” argument, the “fine tuning” argument, etc., etc.
If we don’t have evidence we should be happy to say: “I don’t know.” And, ideally follow that with: “Let’s find out.”
To use lack of information to support a knowledge claim is just not logical.
By the way – the paper is by Carol E. Cleland & Shelley Copley (2005). “The Possibility of Alternative Microbial Life on Earth,” International Journal of Astrobiology 4, pp. 165-173. It discusses the possibility that life may have originated on earth more than once and these forms may be basically different. Peter Ward, in his book Life as We Do Not Know It also discusses this possibility.
It’s intriguing. Maybe we will discover “alien” life on earth before we discover extra-terrestrial life.