...I do suppose I can reasonably understand why some people might not think the idea that all current life evolved from a common ancestor should be regarded as a fact though. We obviously couldn't have directly observed that.
Just like we haven't directly observed nuclear fusion reactions occurring in the sun's core, or that the earth's core is composed of nickel and iron. Yet both of these things are considered
facts.
We may consider something to be a fact if the overwhelming abundance of evidence suggests that it is inconceivable that it is not a fact.
Speaking personally, I find few things more awesome than contemplating this vast and majestic process of evolution, the ebb and flow of successive biotas through geological time. Creationists and others who cannot for ideological or religious reasons accept the fact of evolution miss out a great deal, and are left with a claustrophobic little universe in which nothing happens and nothing changes.
--
M. Alan Kazlev