Logic and reason

Because words have multiple meanings and imprecise meanings we cannot reach the truth by reasoning alone. But words are what we use most often to express ideas. When we speak of truth, we are speaking of the truth of a group of words. We come up with words for things which may or may not exist, such as eternity, infinity, finite, supernatural, divine. Logic and reasoning break down when we get to the extremes of human imagination. Logic and reasoning serve us well in the here and now, but can it apply to eternity, infinity, the supernatural, or the divine?

I personally prefer logical explanations for the things I experience rather than spiritual explanations, but even logic has it’s limits.

10 Replies to “Logic and reason”

  1. So, if I say, “Eternity exists and, oh by the way, eternity does not exist,” does logic not apply to that statement?

    Your statement that “logic and reasoning break down when we get to the extremes of human imagination” is at the extreme of human imagination. Does that mean that logic doesn’t apply to that statement?

  2. Logic appears to me to be a human invention. I tried to use logic in coming up with my statement about eternity, but how do we know if anything like eternity exists? Using logic when discussing imaginary things doesn’t make those things real. How do we know if matter was created or if it has existed “forever?” Certainly you would agree that there is a limit to human understanding.

  3. 1) The Bible is true.
    2) The Bible says Jesus raised Lazarus from the dead.
    3) Therefore, Jesus raised a dead man to life.

    Is syllogism logically sound? Is it true because it is logical?

  4. Logical does not = true. The two terms are unrelated.

    There are plenty of things that people do that are logical but untrue. And there are lots of things that are true but not logical (much of quantum physics)

  5. Logic can be applied to all statements, but it doesn’t necessarily result in revealing the truth of that statement. It is a tool that is helpful in evaluating ideas, but it must be used along side physical evidence.

  6. Perry and you are exactly right (except for the quantum physics part). The validity of a syllogism is completely unrelated to the truth of its conclusion.

    An argument can be valid and true, or valid but false, or invalid but true, or invalid and false.

    However, if a syllogism is valid and both the major and minor premises are true, the conclusion must be true.

    Here’s one that is valid but false:

    1) All talk show hosts are conservative
    2) Jim is a talk show host
    3) Jim is a conservative

    It’s valid because the conclusion follows from the premises, but it’s false because one of the premises is false. Bill happens to be a liberal.

    Here’s one that is invalid but true:

    1) All dogs have 4 legs
    2) Bill’s pet has 4 legs
    3) Bill’s pet is a dog

    Bill’s pet happens to be a dog, but the conclusion doesn’t follow from the premises.

    Now, there is nothing about quantum physics that violates the laws of logic. Logic applies to propositional statements, and no two statements can be correct if they contradict each other. See my last comment at http://www.bobmo.com/2008/04/paradoxes.html.

    Dedwarmo, what do you mean by “physical evidence”? Are you saying that all truth is derived by sensory means?

  7. Things about quantum physics are illogical in a sense that they do not match our typical observations. Based on observation, it’s logical that you should be able to determine the position and place of an object. However, it turns out not to be true because in quantum mechanics you can’t.

  8. Perry, I think what you mean is that quantum physics is counter-intuitive.

    Bobmo, everything I know I learned through my senses, which includes hearing and reading the words of others. I personally have never received knowledge from any other source. Some people claim to have learned things through revelation from God. Even if these “revelations” are consistent with reality, how do I know they really came from God? Some say the test of a prophet is that if what the prophet says comes true, then it was from God. Does that mean when an astronomer predicts a solar eclipse that he is a prophet of God?

    Every time I experience something new I compare it to what I already know. If it doesn’t fit in I begin to doubt myself or I try to come up with an explanation that fits my worldview. My worldview comes from the total of experiences up until that point and it can change when presented with new experiences that force me to modify my worldview.

    When I first saw a magician saw a lady in half I believed that the lady was unharmed and that I had been deceived. I had no evidence, but I based my conclusion on a series of assumptions and observations.

    1. The lady didn’t scream in pain.
    2. No blood leaked from the box the lady was in.
    3. Up until this time all of the magic acts I had seen were fit for a general audience.
    4. I assumed that they would not broadcast a show in which a woman was killed for our entertainment.
    5. The magician “put the woman back together” and I had never heard of this sort of thing ever happening outside of a magic act. Surgeons have never successfully reconnected a severed spinal cord.

    Did I use deductive reasoning to conclude that the woman was never actually cut in two?

    1. A woman cut in two will die.
    2. The woman didn’t die.
    3. The woman was not cut in two.

    It is still possible that the woman’s body was indeed halved and that the magician had some sort of power to separate and rejoin living flesh. So what is the truth in this situation? Until I get to examine the woman carefully in both her separated and rejoined states, I will conclude that she was never cut in half and that the magician was just deceiving his audience.

  9. Dedwarmo, I agree that counter-intuitive is probably the best word for what Perry is describing. It does not violate any law of logic.

    You said that everything you know you learned through your senses, and you personally have never received knowledge from any other source. Is this really true? Can the statement, “All knowledge is derived through the senses” be verified through the senses? I suggest that there are many things you believe which can neither be derived or verified via the senses.

    I don’t know of anyone who says that if a prophet’s saying comes true, that is proof it was from God. I believe you have it backwards. The Bible says that if a prophet’s saying does not come true, he is not from God. Big difference there. Anyone can predict the sunrise. So, no the astronomer is not necessarily a prophet of God.

    Deut. 18:22 “When a prophet speaketh in the name of the LORD, if the thing follow not, nor come to pass, that is the thing which the LORD hath not spoken, but the prophet hath spoken it presumptuously: thou shalt not be afraid of him.”

    You did use deductive logic to conclude that the woman was never actually cut in two, since you went from the known (the assumptions and observations you listed) to the unknown (the status of the woman). Your syllogism is a good example of valid deductive reasoning. And, if both premises are true, the conclusion is true as well.

  10. Bobmo, you ask, “Can the statement, ‘All knowledge is derived through the senses’ be verified through the senses?” Are you saying that using deduction is a way to gain knowledge apart from the senses? Because I have deduced that all of my knowledge has come from my senses.

    I may be mistaken. Some people believe that we are born with the ability to learn languages. Logic and the ability to understand language are closely related. But is this knowledge?

    We may also be born with a certain ability to interpret the colors and shapes that our eyes perceive as distinct objects that occupy three dimensional space.

    We are born with the instinct to seek out a nipple to get nourishment. I didn’t have to learn to breathe or swallow or wiggle my limbs. But can you call this knowledge?

    Is it possible to understand mathematics without ever having counted objects?

    I cannot imagine a color that I’ve never seen. I cannot imagine a sound that I’ve never heard, etc.

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