Myths Dressed as Science
.....Four basic assumptions are necessary to use any radioisotope dating process as a reliable clock:
(1) The system of which the rock samples are a part must be a closed system. This is an increasingly bad assumption with the increasing age of the system.
(2) Decay rates of the isotopes used as clocks must remain constant over time. Again, this assumption becomes more tenuous with the increasing age of the system.
(3) The initial or primordial concentrations of parent and daughter in the system must be accurately known.
(4) For any system ages of long duration, it must be assumed that enough time has passed for measurable levels of the radioactive daughter to have been produced.
All four of these assumptions must hold fast without exception—any exception invalidates the dating method. It is doubtful that any one of these assumptions can be rigorously satisfied over 3.67 million years, much less all four. But the particular dating method used to date Little Foot added one more dubious assumption, i.e.:
(5) The production rates for the cosmogenic radionuclides have remained constant over millions of years.
Since the interstellar radiation incident on the earth's atmosphere varies with the seasons, with weather, with solar activity, with galactic activity, and with variations in the earth's magnetic field, it is extremely unreasonable to expect constant production rates for any of these radioisotopes over the vast amounts of time claimed. To suggest that all five assumptions can be strictly maintained for over three million years is completely untenable.
Why would any scientist publish something as fact when it rests on such a shaky foundation? There are probably many superficial reasons, but it appears the fundamental reason is that these "scientists" are attempting, whether consciously or unconsciously, to indoctrinate the public rather than educate them.
http://www.icr.org/article/myths-dressed-science/