The Laws of Thought

aren’t.

They are perfectly valid rules of reasoning, of course.  Wikipedia cites Aristotle: :

  • The law of identity: “that every thing is the same with itself and different from another”: A is A and not ~A.
  • The Law of Non-contradiction: that “one cannot say of something that it is and that it is not in the same respect and at the same time”
  • Law of Excluded Middle: “But on the other hand there cannot be an intermediate between contradictories, but of one subject we must either affirm or deny any one predicate.”

And of course they work just fine for binary, true-or-false, statements, which is why Boolean logic is so powerful.

But I suggest they are not Laws of Thought.

As far as I can see (and I’m neither a philosopher nor a logician)  they don’t work at all well for probabilistic statements:

  • A thing can be both possibly A but also possibly not-A.
  • A thing can be possibly something, and possibly not something, in the same respect and in the same time.
  • And most importantly, a proposition can be possibly true AND its negation can be also possibly true.

Jacob Cohen in his great paper, The Earth is Round (p<.05) writes:

The following syllogism is sensible and also the formally correct modus tollens:

  • If a person is a Martian, then he is not a member of Congress
  • This person is a member of Congress
  • Therefore, he is not a Martian.

Sounds reasonable, no?  This nes syllogism is not sensible because the major premise is wrong, but the reasoning is as before and still a formally correct modus tollens:

  • If a person is an American, then he is not a member of Congress. (WRONG!)
  • This person is a member of Congress
  • Therefore, he is not an American.

If the major premise is made sensible by making it probabilistic, not absolute, the syllogism becomes formally incorrect and leads to a conclusion that is not sensible:

  • If a person is an American, then he is probably not a member of Congress (TRUE, RIGHT?)
  • This person is a member of Congress.
  • Therefore, he is probably not an American.

All this doesn’t mean that the so-called Laws of Thought are false, but that they aren’t Laws of Thought, because, I submit, thinking is fundamentally probabilistic, and probably (heh), specifically, Bayesian.  The so-called Laws of Thought are a special case of human reasoning applicable when we are dealing with certainties.as we can be, if we define our axioms ab initio, and per arguendo. But in day-to-day reasoning, nothing is certain, and we behave like scientists (at best) or like politicians (at worst) making the best fitting models we can to the data available, and conducting on-line error-minimising optimisation processes in coming to provisional (if we are lucky) decisions or least-risky decisions (if we have to act earlier before we have access to all the data we’d ideally like).

And I suspect that this is why Barry et al at Uncommon Descent have such a Thing about the three classical Laws of Thought.  ID, as she is spoke, is not scientific, although sometimes mathematical, and frequently theological.  Which is not to say ID couldn’t be scientific – it could.  But to be so, its practitioners would have to understand the probabilistic nature of scientific reasoning, and the provisional nature of its conclusions, and for all the ID words that have been written about probability, ID proponents do not, in my experience, fundamentally understand what probabilities are probabilities of, and what information is required to calculate them (even though they define probabilities as bits of information).

I suggest they need to get outside the binary “Laws of Thought”, and start to understand probabilistic Thinking.  Which will also lead to a greater understanding of Intelligence, and thus of Design, but does require dropping the notion that any proposition must be either True or False.

74 thoughts on “The Laws of Thought

  1. The logic is that evolution requires (and predicts) specific geological findings.

    It’s a bit like saying that the bullet found in a victim must match the gun claimed as the murder weapon.

    Logic?

  2. Lizzie: Robert, there are gazillion data points: geological, biological, astronomical, cosmological, subatomicological, you name it.

    What gives us so much confidence about the age of the earth is that these data points collectively give us converging and consilient evidence.To insist that the earth is only a few thousand years old in the teeth of such evidence is to put faith over evidence.Which is your prerogative.But there is no “logical flaw”.

    Nor, to bring us back on track, there a “logical flaw” in inferring from the overwhelming evidence that minds and brains are intimately connected that they way we think is a function of the way our brains work.The brain is not simply a “memory store” for the use of the mind.Indeed I’d question the concept of the brain being a “memory store” at all.

    The memory thing is another thing.
    The logical flaw here I’m stressing is the use of geology to say one has biological evidence for descent and process.
    this is , I say, a logical flaw that dominates evolutionary thinking. and critics of evolution also especially ID confederates.
    Evolutionists proclaim there is this biological evidence for evolution in fossils , genetics, etc YET there is no bio evidence UNLESS the geological evidence is accurate.
    So i cry NOT FAIR and NOT LOGICAL.
    There is a logical flaw here and i think its classic case of a intellectual optical illusion.
    It shows people sincerely see lines of logic where its not.

  3. See my post above. It’s about entailments and confirmation of expectations.

  4. As has been pointed out by many, even if fossilization didn’t happen and geology were entirely irrelevant (except for establishing an overall time frame), the evidence for evolution would still be overwhelming.

    The fossil evidence is a nice convenient illustration that the process DID happen over eons of time, and gives us interesting details about the history of life on earth, but it’s not really required. Descent with modification, common ancestors, and the like are not based on anything geological, just as you say.

    Of course, the concepts of geology are not in dispute either, and do not rely on anything biological. These concepts are not “presumptions”, they are solidly-based theory. The small amount of overlap between geological and biological history isn’t used to establish either one, it’s just noteworthy that the observed overlaps happen to be consistent with both theories.

  5. Robert Byers
    I think i’m right here.

    Of course you do. However, as I told you already, there is loads of evidence for evolution that does not directly rely on geology, so your premise is wrong.

    Besides, using knowledge from another field is not illogical. If you think there is a “logical flaw” then tell me WHICH logical fallacy?

  6. petrushka:
    See my post above. It’s about entailments and confirmation of expectations.

    I don’t understand quite your point.
    I could say confirmation of expectation is what goes on in evolutionary claims that of biological evidence from fossils, genetics etc.

    If there is a logical flaw going on here then it would keep going on since its not obvious. everyone is logical and so a flaw is only discovered upon careful reflection.
    More reflection is needed here by one party.

  7. davehooke: Of course you do. However, as I told you already, there is loads of evidence for evolution that does not directly rely on geology, so your premise is wrong.

    Besides, using knowledge from another field is not illogical.If you think there is a “logical flaw” then tell me WHICH logical fallacy?

    I have been striving to explain it.
    ITS that a logical flaw is made because evolutionary biology presents AS BIOLOGICAL EVIDENCE conclusions from looking at biological data points and these conclusions only are true IF the geological facts are true.
    If the geology is not true neither is the biological evidence for evolution.
    So i say its not accurate to say fossils, genetics, etc are BIOLOGICAL evidence for evolution. Therefore evolution has no or less biological evidence based on scientific investigation.
    Whew!
    I can’t do it in numbers so its more obvious but a logical flaw has and is being down by evolutiondom. A big flaw.
    They must revoke evolution from being a biological theory and instead turn it into a hypothesis waiting for evidence.
    why am I wrong here!
    A thread about logic should be on the ball.

  8. You don’t know what a fallacy is, so I don’t really know why I asked.

    Do you agree with this:

    “It can only be true that Alice is six years old if the Earth is at least six years old.”

    In other words, is that statement true?

    (Let’s assume Alice is human and all humans so far have been born on Earth)

  9. davehooke:
    You don’t know what a fallacy is, so I don’t really know why I asked.

    Do you agree with this:

    I do kniw whar a fallacy is.
    Yes Alice could only be at most six if earth is just six.

    “It can only be true that Alice is six years old if the Earth is at least six years old.”

    In other words, is that statement true?

    (Let’s assume Alice is human and all humans so far have been born on Earth)

  10. Okay, so the reasoning about Alice’s age being reliant on a geological fact (the age of the Earth) is good logic. We say, it is valid.

    Now, Alice’s age is a fact about Alice, yes? Not a fact about geology.

    Although it can only be true if the geology is true (if the Earth is at least six years old), we can find out Alice’s age without doing any geology.

    Now, if the Earth was only four years old, there is STILL no logical flaw in the reasoning. “Alice can only be six years old if the Earth is at least six years old.” is STILL true. It will ALWAYS be true.

    The same, perfectly valid reasoning can be applied to the theory of evolution:

    “The theory of evolution can only be true if there is enough time for evolution to happen (i.e the Earth is quite old).”

    There is no logical flaw in this reasoning.

    Now what if we find evidence that Alice is six years old from her birth certificate, her mother’s testimony, the school year she is in, and a photograph of her as a baby at a 2007 election rally? The evidence does not rely on the geology. There is no logical flaw in using the evidence to find she is six years old.

    If we think the Earth is only five years old, but we have evidence that Alice is six, we have to try to reconcile these two things. All our facts must be consilient. Now, the fact that Alice is six years old (from the evidence) is itself some evidence that the Earth is at least six years old.

    In the same way, genetics is BIOLOGY but also provides evidence that the Earth is old.

    Each fact in science should agree with all the others (in an ideal world). There is nothing illogical about the fact that biological facts depend on geology being true, or that a geological fact might depend on biology being true. There is no flaw in logic.

    Questions?

  11. Robert Byers: I have been striving to explain it.
    ITS that a logical flaw is made because evolutionary biology presents AS BIOLOGICAL EVIDENCE conclusions from looking at biological data points and these conclusions only are true IF the geological facts are true.
    If the geology is not true neither is the biological evidence for evolution.
    So i say its not accurate to say fossils, genetics, etc are BIOLOGICAL evidence for evolution. Therefore evolution has no or less biological evidence based on scientific investigation.
    Whew!
    I can’t do it in numbers so its more obvious but a logical flaw has and is being down by evolutiondom. A big flaw.
    They must revoke evolution from being a biological theory and instead turn it into a hypothesis waiting for evidence.
    why am I wrong here!
    A thread about logic should be on the ball.

    Robert Byers:

    So you don’t think that geology as the scientific world understands it is “true”?

    Why on earth not? What flaws have you discovered in the methods used for dating rocks?

  12. davehooke:
    Okay, so the reasoning about Alice’s age being reliant on a geological fact (the age of the Earth) is good logic. We say, it is valid.

    Now, Alice’s age is a fact about Alice, yes?Not a fact about geology.

    Although it can only be true if the geology is true (if the Earth is at least six years old), we can find out Alice’s age without doing any geology.

    Now, if the Earth was only four years old, there is STILL no logical flaw in the reasoning. “Alice can only be six years old if the Earth is at least six years old.” is STILL true. It will ALWAYS be true.

    The same, perfectly valid reasoning can be applied to the theory of evolution:

    “The theory of evolution can only be true if there is enough time for evolution to happen (i.e the Earth is quite old).”

    There is no logical flaw in this reasoning.

    Now what if we find evidence that Alice is six years old from her birth certificate, her mother’s testimony, the school year she is in, and a photograph of her as a baby at a 2007 election rally? The evidence does not rely on the geology. There is no logical flaw in using the evidence to find she is six years old.

    If we think the Earth is only five years old, but we have evidence that Alice is six, we have to try to reconcile these two things. All our facts must be consilient. Now, the fact that Alice is six years old (from the evidence) is itself some evidence that the Earth is at least six years old.

    In the same way, genetics isBIOLOGYbut also provides evidence that the Earth is old.

    Each fact in science should agree with all the others (in an ideal world). There is nothing illogical about the fact that biological facts depend on geology being true, or that a geological fact might depend on biology being true. There is no flaw in logic.

    Questions?

    I missed the words “at least” and thought it was “only”.
    Nevertheless we are talking about the logic behind saying evolution is a biological subject and conclusion yet using, as you seem to admit, geological presumptions.
    Without these the biology is not true.
    Yet I go further and say that therefore evolution is not a biological theory because its main claims to evidence, or all, are not based on biological investigation.
    They are just biological conclusions based on biological data POINTS and then the evidence for descent/process is based entirely on sequence in rock stratas and in observation of morphological differences. Yet descent/process is presented as coming from biological investigation.
    Thats the rub.
    Thats the logical flaw here in say evolution is a scientific biological investifgative conclusion.

    If you will admit evolution has NO biological scientific evidence behind its claims for evidence then we can talk.
    Yet it will mean the endo of it being a biological theory. It will be a gypothesis with non biological but elements of other evidence from other fields of study.
    I still see the logical flaw has and is still about misunderstanding the difference between biology and geology with biological speculations of relationship of data points.

    Remember if a space alien gave us a video of what happened it would be great conclusive evidence for evolution, Yet it would not be evidence from biological investigation.
    Yet it would prove the truth with other evidence. Yet can’t claim to have proven evolution by biological investigation. Just raw observation of the video.

  13. damitall2:
    So you don’t think that geology as the scientific world understands it is “true”?

    Why on earth not? What flaws have you discovered in the methods used for dating rocks?

    Its off thread here.
    I am striving to show careful thinkers that evolutionary biology is largely based on non biological investigation of natures evidence.
    Their best points are not from scientific biological investigation. Yet they think they are. A great modern logical flaw in science.
    Its not about the merits of geological conclusions.
    Its about them being the origin for biological conclusions of descent and process.
    They are mimicing biological evidence and so a error has occurred.

  14. Robert Byers: Its off thread here.
    I am striving to show careful thinkers that evolutionary biology is largely based on non biological investigation of natures evidence.
    Their best points are not from scientific biological investigation. Yet they think they are. A great modern logical flaw in science.
    Its not about the merits of geological conclusions.
    Its about them being the origin for biological conclusions of descent and process.
    They are mimicing biological evidence and so a error has occurred.

    Then I don’t understand what your point is. Are you then saying that fossils are NOT the accurately preserved remains of actual living creatures? That the study of fossils tells us nothing about their age, or the biological characteristics of the creatures themselves?

    You are a self-proclaimed Young Earth Creationist. I would have thought that ou would have some cogent reason as to why you believe that the earth is less than 10,000 years old.What have you got against “lines of reasoning”? Do you yourself not use “lines of reasoning” in coming to your conclusions about the age of the earth?

  15. I suppose I shouldn’t be surprised you didn’t understand anything I said.

    the evidence for descent/process is based entirely on sequence in rock stratas and in observation of morphological differences.

    No, it isn’t. You forget genetic evidence. Also, the biogeography of living species is evidence for evolution.

  16. Robert Byers: I am striving to show careful thinkers that evolutionary biology is largely based on non biological investigation of natures evidence.

    That’s going to take some difficult striving, since it is so obviously false.

  17. davehooke:
    I suppose I shouldn’t be surprised you didn’t understand anything I said.

    No, it isn’t. You forget genetic evidence. Also, the biogeography of living species is evidence for evolution.

    It is . Relative to the case when they invoke biological evidence. Genetics is another case for wrong use of evidence. However thats another point.

    Its not about evidence for evolution but about the logical flaw of using biological data points, and their connections, and this connection only discovered by geological information.
    Flaw aplenty.

  18. damitall2,

    Yes lines of reasoning as opposed to scientific evidence is a criticism I strongly make!!
    Yes fossils show biological facts about the dead creature.
    Yet its in connecting the creature to others by descent and evolutionary process/or any process that IS NOT shown by fossils.
    Yet evolutionists think it is shown by fossils.
    A logical flaw. Persistent because its not obvious to intelligent people in these fields of study. A logical flaw must be dug out and this is why logic has been a subject in higher learning. Its mot just common reasoning but more careful reasoning.

  19. Neil Rickert: That’s going to take some difficult striving, since it is so obviously false.

    Well if false then it shouldn’t be hard to show me.
    Both sides need to strive .

  20. Robert Byers: I am striving to show careful thinkers that evolutionary biology is largely based on non biological investigation of natures evidence.

    Well, for a start, the original idea came from the observation made by Linnaeus and others that living things can be plotted as a tree diagram based on heritable characteristics.

    That was purely biological, and strongly suggests a family tree.

    However, the time scale over which such a tree must have formed has been informed by many independent lines of evidence, including both geology and astronomy.

    So we have the necessary time scale, and evidence of a famiily tree. Then came along biological evidence regarding the mechanisms of heritability (genetics, and DNA), as well as actual lab and field experiments that show the proposed adaptive mechanisms happening in real time, and also biological evidence for speciation, including evidence from ring species, and from actual examples often from botany.

    So no, evolutionary theory is not “largely based” on non-biological evidence although non-biological evidence is extremely important, and what makes evolutionary theory so persuasive is the consilience between results from independent lines of enquiry.

  21. Lizzie,

    Lizzie
    The great points I see made to claim evolution is a biological theory are points about fossils, genetics, morphology, even biogeography.
    I say none of these are scientific biological evidence to justify evolution as a theory. As opposed to a hypothesis.

    This family tree would only have specific fruit. Just data points and then connections. There is just the conclusion that profound morphological likeness equals common ancestry. This is surely true for horse types or people. Yet further connections is just picking trails in creatures and drawing connections of ancestry.
    Its just that and no more investigation then that.

    Is there a little biological scientific investigation behind evolution??
    Well its minor stuff on changes that haoppens within types of creatures. Its not showing what is needed. The great biological change that is needed for new directions in these creatures that can lead to more changes.

    Its not about evidences for evolution but about is the biological evidence for evolution that evolutionists present REALLY biological scientific evidence for evolution.
    I say it isn’t.
    There has been a logical flaw , real and true, in evolutionists (perhaps some creationists) thinking there is by what they think it is .
    Logic thinking is more then ordinary logical thinking of mankind. Its a careful correction to conclusions not accurately drawn from claimed evidences.

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