I was never comfortable with the pat answers that denied conversation (and thus relationship), and I now am realizing how many things we can't know with complete certainty. (nakedpastor.com)
Female mammals are capable of producing far fewer off - spring, but have almost complete certainty about which are theirs. (religion-online.org)
They announced that although the climate system was so complex that scientists would never reach complete certainty, it was much more likely than not that our civilization faced severe global warming. (scientificamerican.com)