Dr. Hovind (G5): The assumed age of a sample will dictate which radiometric dating method is used. One method will only give results for a young age; another will only give results for a very old age. Thus, the assumed age of a sample dictates the method which, in turn, gives the assumed age!
G5. That seems to be the substance of Dr. Hovind's complaint, a complaint that has been made by other creationists.
Are we to believe that the world's leading geologists cannot recognize an elementary case of circular reasoning? Is that the real explanation behind their choice of isotopes in radiometric dating? Of course not! Those creationists arguing thus have been grievously blinded by their religious prejudice, against which a Ph.D. is no defense.
The problem lies with Dr. Hovind and many other creationists who haven't the foggiest idea how radiometric dating works! They are the last people who should be criticizing it. The explanation is so easy that quotations from specialists won't even be necessary.
If you test an old sample with a radiometric method geared to young samples, you will find that all the "parent" radioactive atoms have decayed. Your conclusion will be that the sample has a minimum age which corresponds to the smallest amount of the "parent" nuclide you can detect. You would not conclude that the sample was much younger.
If you test a young sample with a radiometric method geared to old samples, you will find that none of the "parent" radioactive atoms have decayed. Your conclusion will be that the sample has a maximum age which corresponds to the smallest amount of the "daughter" nuclide which you can detect. You would not conclude that the sample was much older.
The realities of the laboratory, of course, mean that there are no sharp cut-off points. Instead, there will be ranges, and at the extremes the results can only give a rough maximum or minimum age. Dates landing in that zone would be considered unreliable.
It's a little like weighing a flea on a scale used to weigh trucks or weighing a brick on a scale designed to weigh envelopes. If the brick depresses the scales all the way to the highest mark, you conclude that the brick weighs at least that much. If the flea doesn't depress the scales at the truck stop, you conclude that it weighs less than a weight which barely moves those scales.
Consequently, the choice of scales will not dictate the result. Of course, if the truck scale isn't perfectly calibrated, you might get a 50-pound flea! Similarly, the envelope scale would indicate that the brick only weighs a few ounces. However, no one who is familiar with such scales would take those readings too seriously. A similar situation holds for radiometric dating. Readings falling in the minimum or maximum zones are not taken too seriously. Thus, there is no problem.
Was that so difficult?