Is carbon dating accurate?

Question

If so, then why do scientists date fossils by the rocks nearby, but date rocks by the fossils nearby?? Isn't this "circular reasoning"?

Answer 1

No. The only way of confirming its accuracy is to date objects that we already know how old they are. These fall into the scope of the last 5000 years, a period which they already say is less accurate than when measuring older objects. Scientists always seem to be arguing about the age of things regardless of what the carbon dating says.

Answer 2

Carbon dating isn't used on fossils, it's used on organic remains under 50,000 yrs old, other radioisotopes are used for fossils.

They don't just pick up random stones, they get the 'rocks' by taking samples from the same layer the fossil is embedded in. They don't date stones by looking at nearby fossils. Certain well documented fossils indicate the rock probably comes from a bracketed time period, but you can't always find a well documented species in the same stratum with a less well documented species.

Dates aren't determined by just one one method. Scientific dating requires multiple lines of confirmation, not just a rough guess.

No it isn't circular reasoning.

Circular reasoning is when you try and restate your premise and try and pass it off as proving your premise.

http://www.nizkor.org/features/fallacies/begging-the-question.html
here's an example from the site:

Bill: "God must exist."
Jill: "How do you know."
Bill: "Because the Bible says so."
Jill: "Why should I believe the Bible?"
Bill: "Because the Bible was written by God."

Answer 3

the short answer to the question "is carbon dating accurate?" is yes, sort of - depending on the situation...and sometimes, no

the first problem is that you have either misasked your question, asked the wrong question, or you don't understand the differences between carbon dating and the other radiometric dating methods

it is the other radiodating methods that date the rocks nearby primarily (ie, U-Pb, Sr-Sr, Sr-Rb, etc)

i am assuming that you really meant to ask about radiometric dating rather than carbon dating specifically...but don't worry, this is a very common mistake; many people, maybe even most people refer to radiometric dating as a whole as carbon dating

the clarification or subquestion following your main question is the part that confuses things; by that i mean that what you say following is true but only applies to other radiodating methods, not 14C

14C can only be used on biological materials (ie, plants, animals) and measures the amount/ratio of 14C that has decayed into 12C/13C

as long as the organism is interacting ("living" we can discuss different definitions of "living" another time) with the atmosphere (respiration/transpiration) then it is (in the present) cycling through its system a certain ratio of C14-C13/C12

14C has a halflife of ~5340yrs + or - 40-60yrs...when the organism "dies" (or ceases to interact with the atmosphere as noted above) the cycling process ceases and the 14C radiocarbon clock begins to tick

so in this regard 14C is different from the other radiodating methods in that it only deals with organic material

fossils on the other hand, are technically rocks (ie, the organic material has been replaced by mineral material although it has retained its original shape, form, and sometimes in very intricate detail) so there is no biological material (at least in any "fossilized" portion) left to date via carbon dating

if you meant to ask, "is radiometric dating accurate?" the answer is a resounding NO, at least not with any measurable consistency (we can go there another time) and it is certainly not independent

but to go on...

actually, contrary to someone above that opined that 14C dating was less accurate in the last 5000yrs, it is more accurate for about the last 4000yrs and less so for longer ages

there are a number of problems with all radiometric dating methods

one of the biggest problems is the initial assumptions...

problem numero uno -- uniformitarianism (the cornerstone of radiometric dating techniques) - the concept that processes have always occurred at the same rate that they are occuring today; unfortunately, this mixes observational science and historical science (observational/operational science is what we can see and measure in the present -- historical science is that which we did not observe in the past and about which we must make certain assumptions -- sadly, many scientists forget that there is a difference and most non-science folks are not even aware that there is a difference or that the difference should be considered)

stated another way, uniformitarianism is often thought of as "the present is the key to the past" -- we observe the rates at which processes occur today and extrapolate those same rates into the unobservable (or indirectly observable) past

this is more easily controlled in terms of the recent past, but somewhere back there in time (probably not far, more in a minute), a lot of carbon was removed from the cycle; today we find a seam layer that is in some cases miles thick of carbon buried in the so-called "geologic column" (called the "carboniferous"); probably resulting from a worldwide flood that raked huge amounts of plant and animal material from the face of the planet and buried it...rapidly, which is why we even have most fossils at all

fossils are virtually always associated with water deposition and can only form if covered RAPIDLY (not slowly, slowly over millions of years :-)

gradualistic processes in regard to fossil formation are sublimely ridiculous

another problem or assumption with radiometric dating is the original "mother/daughter" elemental composition (and this is a much bigger problem with the "long-age" dating methods and less so with 14C (carbon dating can only be done to about 50,000yrs, maybe 100,000 or a little more; the half life is just too short and the original amount/ratio of 14C too small so that there wouldn't be any measurable amounts of 14C left after that period of time...the times mentioned above are maximums not minimums, and that's important for reasons that we can also discuss another time)

the assumption is that the ratios of the mother element (the radioactive isotope) and the daughter element (the degraded form of the radioisotope) are known

in other words, there could not be any non-radiogenic lead in U-Pb system or that all of the lead was radiogenic (decayed from radioactive uranium); which is clearly not necessarily the case because we have documented non-radiogenic lead (naturally occuring lead that is not the result of uranium decay)

in this particular scenario we are not discussing carbon dating so much as the other radiometric isotopes such as uranium (mother element) and radiodecayed lead (daughter element)

there are more issues, at least 7 axioms (unprovable assumptions) involved in radiometric dating

in regard to radiometric dating other than carbon dating, where they don't date the fossils but rather the rocks in the same stratum, you are quite right...it is circular reasoning

they already know what date they are looking for (and by the way, they send that info to the lab along with the specimen(s)), the guys in the lab also have a background in geology, and have thus been instilled with the preconception of the "geologic column" and know what date they should be looking for

dates that don't agree with what they are expecting are relegated to the "anomolous"/"contaminated" file and are either not reported at all or relegated to footnotes (and far more often they are discarded)

so if they only report the dates that agree with their preconceived geologic column, with everything they were indoctrinated with by their uniformitarian, gradualistic, lyellian, evolutionary professors, then its amazing...the dates and the assumed dates agree :-)

in regard to carbon dating, it is generally more accurate back to about 4-5000yrs ago, and less so thereafter

and we can talk about the false radiocarbon dates that have been submitted over the years, that have now been exposed, and by which many other radiocarbon dates were gauged...another time :-)

Answer 4

Carbon 14 dating is quite accurate.

Answer 5

Very accurate.
Scientists normally do not want to take samples from fossils and damage them.

Answer 6

Carbon dating seems to be low; that is, things are much older than they imagine