Circular Reasoning in Fossil Dating?

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I found this gem on Wikipedia:

The occurrence of species of animal that became extinct at ~1.5 Ma indicate the deposit is not younger than 1.5 Ma.

This isn’t science, logic, or reasoning. This is mythology. Just make up a date, pronounce species to be dead after such a date, and voila! You’ve got ancient fossils everywhere.

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7 Responses to “Circular Reasoning in Fossil Dating?”

  1. Tensor Says:

    Try reading it again:

    The fossil was dated using a combination of palaeomagnetism and uranium-lead (U-Pb) dating which showed that the fossils are not older than ~2.0 Ma. The occurrence of species of animal that became extinct at ~1.5 Ma indicate the deposit is not younger than 1.5 Ma. The sediments have a ‘normal’ magnetic polarity and the only major period between 2.0 and 1.5 Ma when this occurred is the Olduvai sub-Chron between 1.95 and 1.78 Ma.[5] As such, the fossils were originally dated to ~1.95 Ma. Recent dating of a capping flowstone illustrated this was not possible and the normal magnetic polarity sediments have since been correlated to the 3000 year long Pre-Olduvai event at ~1.977 Ma.

    So, to which of those many methods do you object, and why? Please show your work, or no credit.

    • Jonathan Gardner Says:

      I object to the circular reasoning part. The statements says that the fossil cannot be younger than 1.5 Ma because the fossil is of a species that died out 1.5 Ma. What kind of reasoning is that?

      Since you are not going to respond to this critical flaw, I will add another challenge. How do we tell the age of layers of rock: by the fossils we find in them? How do we find the age of the fossils: by the layers of rock they are in? Here is another fatal flaw in these so-called scientist’s reasoning. Simple logic that overthrows their arguments completely.

      • demokid Says:

        I object to the circular reasoning part. The statements says that the fossil cannot be younger than 1.5 Ma because the fossil is of a species that died out 1.5 Ma. What kind of reasoning is that?

        If you can’t handle basic reading comprehension, don’t try to argue. This is stating that the strata that the fossil was found in had OTHER fossils of species that were extinct by 1.5 Ma, proven through other methods.

        This is the problem with people that falsely believe that the Earth is 6000 years old. Thinking that small misinterpretations somehow upend a consistently defended theory in science, one that explains observations far better than a strict religious interpretation, is laughable and goes against all rules of logic and evidence.

      • Jonathan Gardner Says:

        Rather than insult my reading ability, why don’t you show me how you’ve avoided the circular reasoning? You’ve just made things worse by muddying the waters.

        So what if the strata the fossils were found were inhabited by species which went extinct 1.5 Ma ago. How do we know this? What if we found fossils that were obviously not from 1.5 Ma in that layer: do we need to redefine what we thought was correct about the layer, or do we just define it as older than 1.5 Ma because that’s what we said it should be?

        And this isn’t a small thing. They’re trying to put bounds on the age of the fossil, and they can’t do it. They have a very fuzzy bound in one direction, based on assumptions that simply can’t be proven about the initial state of radioactive material in the sample, as well as assumptions about radioactive decay that may not be true (IE, it may not be constant over time), and they have another bound on the other end, based on circular reasoning.

        I’ve pointed out an obvious flaw in their reasoning, something that even a child could pick up if they looked closely at it.

  2. tensor Says:

    Since you are not going to respond to this critical flaw…

    The evidence provided by the other fossils is in no way “critical” to the dating of the find in question, as the entire paragraph attests. The dating was made via chemistry (“uranium-lead (U-Pb) dating”), geology (“dating of a capping flowstone”), and geophysics (“normal magnetic polarity sediments”); the presence of other fossils was merely confirming information. It was not the basis for the dating. and therefore could not have been in any sense “critical”.

    Furthermore, the “flaw” here is entirely in your reading comprehension, as demo kid pointed out. You took this sentence:

    The occurrence of species of animal that became extinct at ~1.5 Ma indicate the deposit is not younger than 1.5 Ma.

    And turned it into this:

    The statements says that the fossil cannot be younger than 1.5 Ma because the fossil is of a species that died out 1.5 Ma.

    Not only did the original sentence clearly refer to the entire ‘deposit’, NOT to a single ‘fossil’, but that this deposit contained plural remains (‘species’)! This would have told any competent reader that the sentence must be referring to multiple finds in the same layer.

    …I will add another challenge. How do we tell the age of layers of rock: by the fossils we find in them?

    Since you have not yet understood the very paragraph from which you selectively quoted, I reiterate my original challenge: please read the paragraph again. In this case, the answers are chemistry, geology, and geophysics.

    … why don’t you show me how you’ve avoided the circular reasoning? You’ve just made things worse by muddying the waters.

    He showed that you completely misunderstood the very sentence you had quoted. The only circular reasoning to avoid here is your own.

    So what if the strata the fossils were found were inhabited by species which went extinct 1.5 Ma ago.

    So, it is a detail which confirms the chemistry, geology, and geophysics used to make the original dating. You’re taking a confirming detail and pretending it’s the opposite of what is.

    They’re trying to put bounds on the age of the fossil, and they can’t do it.

    The geophysics put exceptionally tight bounds upon it:

    … the normal magnetic polarity sediments have since been correlated to the 3000 year long Pre-Olduvai event at ~1.977 Ma.

    On the time-scales in question, a mere 3,000 years is very small.

    … as well as assumptions about radioactive decay that may not be true (IE, it may not be constant over time),

    Please provide evidence of non-linear rates in radioactive decay, especially of the elements in question.

    What if we found fossils that were obviously not from 1.5 Ma in that layer…

    What if there were flying pigs? Then we’d have to explain porcine aviation. But we have no reliable evidence for flying pigs, and therefore we don’t bother worrying about the “issue” of porcine aviation, because it does not exist.

    • Jonathan Gardner Says:

      You have yet to reply to the central idea.

      You said that the statement refers to the deposit, and alongside the fossil were other fossils of species which did not live past 1.5 Ma ago. Why? Because it is.

      You’re only confusing the matter by bringing new things in. Please don’t do that. Address the central concern, or cede the point.

      Why is it perfectly valid to assume that the fossils in a layer are not younger than a certain age? Is it simply because we have defined them to be extinct after a certain age? What if those fossils in those layers are actually younger?

      Also, RE the rate of decay over time: When you reason with physics, you have to state, clearly, your assumptions. We generally assume, for instance, that the speed of light is constant, meaning it doesn’t change, over space or time. This may not be a valid assumption, even though it seems perfectly reasonable. (It really isn’t “reasonable”, since it’s an assumption, and assumptions aren’t based on reason or logic.) We can only observe with any degree of accuracy around our space and time, and so we can say, somewhat confidently, that it holds true immediately around us. Some cosmological explanations have the speed of light changing over space and/or time.

      We also assume that nuclear decay rates do not change over time. However, there are hints that this may not be so. http://phys.org/news202456660.html I don’t know of any theory which predicts variable rates of decay, but we have some observations that suggest just that. If so, this means all the math involving the age of the earth based on nuclear decay may be wrong, possibly by several orders of magnitude. (Who knows? Maybe 6,000 could still be correct? Show me a person who is absolutely confident, and I’ll show you why they have no reason to be so confident.)

      When you reason logically, you can attack the assumptions or the reasoning if you want to overthrow the conclusion. Please be more conscientious about that.

      Also, observations that contradict reasoning mean that the reasoning is wrong. That’s what makes a Physicist a Physicist and not a Mathematician. Mathematicians are bold enough to say the observation was wrong. My God is reality, not human reason.

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