[bobdsmith]

Yes I think there definitely is meaningful distinction between natural and artificial. The origins of a car would be artificial imo. I would disagree with anyone who describes a car's origins as natural.

[inquest]

So I'll come up with a more plausible example, then. Say we find something that looks like an artifact on Mars, or a tantalizingly artificial-looking radio signal through SETI. Could science, through elimination of possibilities, at least be able to demonstrate a high probability that what it discovered is indeed artificial?

[Louis Foxwell]

I would disagree with anyone who describes a car's origins as natural.

Then an ant hill is not natural?