14C Calibration and Correlations

An assertion is not an argument, and verifying one thing by reference to another thing is not circular reasoning.

As for the conservapedia article, the claim of "circular reasoning" in it is supported (and I use the term loosely) by a statement in an article by a creationist which is supported by nothing.

Now, back in the real world, the guys who came up with carbon dating verified its accuracy by reference to objects the dating of which did not depend in the least on carbon ratios:

(See Arnold and Libby, "Age determinations by radiocarbon content: Checks with samples of known age", Science, 1949.)

This is not circular reasoning. This is this thing called "the scientific method" that you may have heard of. It beats creationists making stuff up every time.

Well ... it is. This is one of the first things that was checked --- by the Curies, whom I presume you've heard of --- right back when radioactive isotopes were first discovered. They looked to see if the decay rate was affected by any environmental influences such as temperature or pressure. They drew a blank.

Throwing the sample into a nuclear reactor might skew your results, I guess ...

Besides which, we can check radiocarbon dating against dendrochronology and the formation of varves in proglacial lakes. In order for radiocarbon dating to be wrong, they'd have to be wrong too, which would mean that three totally unrelated processes would have had to go wrong in lock-step with one another.