experimentation and observation (both directly and indirectly) on a small scale Well, measurements that show the earth is about 4.5 billion years old and the Universe about 14 billion years old do not seem to me "small-scale".
One of the many beauties of evolution is that it incoporates a vast age that is fully supported by physics and astronomy and geology in many converging lines of evidence.
But can you prove via your criteria (direct experimentation/observation) that Caesar or Jesus actually existed?
I don't throw the words "inference" and "proof" around so lightly. It is observations on a small scale that lead some scientists to make inferences on a wider scale regarding the age of the earth. I do not count the proposition of a 4.5 billion year old earth as unreasonable or preposterous. It cannot be from direct observation and experience that this figure is proposed. I certainly see no reason to accept this figure as the only one allowed by law in public schools, and would posit that most people accept this figure, like they accept a heliocentric solar system, not by experience but on the basis of testimony from others.
My faith in the historic existence of Caesar (whichever one you might suggest) and Jesus depends upon the testimony of others outside myself and not by direct observation and experience.
Must run off to a gig. Thanks for the correspondence.