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Posts posted by pmb

  1. Yes indeed and further the use of the word critical ( and criticism) needs comment for it is used here in its formal sense.


    As such you must start with something to criticise!

    This would be a good place to mention straw arguments since we get them a lot and giving them a name and recognizing them will help us identify them more readily. This too is a term that appears in discussion forums.


    This text defines a straw arguemnt as follows

    attackiong a straw arguement occurs when a weakened imitation of an opponent's arguement is attacked instead of the opponents the opponents's original arguement because the imitation is easier to refute. The weakened imitation is known as a straw arguement.

    I'm sure we've all seen these in our travels. :rolleyes:

  2. Right. Because insults and personal attacks in no way have any overlap in meaning.




    That's only the short version if you ignore the qualifying statement . "Whenever we attack a person instead of his or her argument" Ad hominem must have that second element: the personal attack must be at the expense of addressing the argument. IOW, ad hominem is a subset of personal attacks.


    In post #3 you agreed that "An ad hominem doesn't argue a point." It's quite clear that your adversary was arguing a point.

    He never argued a point. What he did was to explain something that had nothing to do with my comment. One has to be cautious not to confuse an explaination with an arguement. All he did was to explain that the purpose of his post was fulfilled. Only the later part said that I was "out to get him."


    If he actually provided an argument it would have been an attempt to prove that a photon with non-zero rest mass could move at the speed c when in fact de Broglies photon (which he was talking about) had a nonzero rest mass and moved at speeds less than c. The opponent never made an attempt to prove that the photon with rest mass moved at speed c. If he did then things would be different.


    Let us once again recall the text but this time tear it apart and analyze it piece by piece.

    Read the text again

    Whenever we attack a person instead of his or her argument, we commit a form of the fallacy known as the personal attack. Historically, this fallacy has been known a argumentum ad hominem, or ad homenim for short.


    Now let's break it into pieces. The first part states

    Whenever we attack a person instead of his or her argument, we commit a form of the fallacy known as the personal attack.

    This sentance states that a personal attack is a fallacy which happens when one attacks the person rather than the argument.


    The opponent, instead of arguing that v = c (1) explained why his posts served its purpose and (2) attacked me by essencially saying "you're out to get me".


    #1 was an empty attempt to do anything since (a) I agree that it served its purpose and (2) didn't touch on the points on the comments he was responding to. There was absolutely no attempt to prove that v = c for photons with rest mass.


    #2 was an attack on my character, thus making that statement a personal attack/ad hominem.


    The second part states

    Historically, this fallacy has been known a argumentum ad hominem, or ad homenim for short.

    This sentance explains that the personal attack fallacy is a synonym for ad hominem.


    This is why its quite clear to me and others that it's an ad hominem.


    I just found a ".edu" web site on Logic. It describes an ad hominem too.


    Argumentum ad Hominem (abusive and circumstantial): the fallacy of attacking the character or circumstances of an individual who is advancing a statement or an argument instead of trying to disprove the truth of the statement or the soundness of the argument. Often the argument is characterized simply as a personal attack.


    The personal attack is also often termed an "ad personem argument": the statement or argument at issue is dropped from consideration or is ignored, and the locutor's character or circumstances are used to influence opinion.



    The fallacy draws its appeal from the technique of "getting personal." The assumption is that what the locutor is saying is entirely or partially dictated by his character or special circumstances and so should be disregarded.

    The underlines are mine. This too explains that the terms personal attack and ad hominem are synonyms.

  3. (Bypassing your question)


    I see no reference to freethought.

    From what I read in your link freethought doesn't apply to the list of criteria for critical thinking. Critical thinking is about taking a given case and presenting a cogent argument to support its premises. That doesn't apply to freethought. That seems to be an entirely different subject.

  4. We are trapped in our horizon, we can't see outside observable universe. Physicist says that universe can be finite or infinite.


    My Question is, we know that universe began 13.75 billion years ago. The universe isn't infinitely old, so how the universe can be infinitely big? If it had finite time until today?


    Also if the universe began with certain amount of energy and had a definite size how can be universe infinite?

    A flat universe is infinite in size. It was infinite in size when it was created. Think of a rod which is infinitely long and has tick marks on it to mark of space and there's an infinite number of tick marks. Let the distance between the tick marks increase with the distance between galaxies. Think of it like this - the distance between the tick marks before the big bang was zero meaning that the size of the universe was zero. Now let the Big Bang happen -> even the most smallest but finite distance between the tick marks being created would lead to an infinite universe.


    Yes. It all sounds bizzare. Nobody said cosmology was going to be easy to understand. The fact is that nobody knows how it can be this way. We just have a good handle on how to describe it.

  5. Sure. Like when they conflate a mere insult with an ad hom argument.

    I gotcha. I bet that's why that straw argument about insults kept comming up. I.e. I think people thought I was confusing insults with ad hominems, when I never was. I guess they're so used to seeing it that it may have been a knee jerk reaction to the topic. It was very strange since I never mentioned insults in this thread and I have no recollection about talking about insults in any other threads. People are always claiming that what they write isn't an insult so I never accuse anyone of making one, even when its overly obvious.


    Thanks iNow!

  6. Addendum to pmb's description.


    A field need not extend to all space, just some region of space. However there must be a scalar or vector assigned to each and every point in that region.

    I can't think of a counter example. Its quite reasonable to assign a vector to every point in space, even if the vector is the null vector.


    The region need not have the same number of dimensions as the space. So in 3D space the region may be only 2D ie a surface. This is very common. For instance the surface of a shell or sphere is often used.

    The 2-d space is a subspace of 3-d. All you do is evaluate the field over the surface in question. Each point on the surface is still in 3-d. But its kinf of unnatural to restrict an electric field to a 2-d surface. I can't even think of an example except for things like a gaussian surface. But that surface is embeded in 3-d space.

  7. I guess I got it from this post

    That post says nothing about insults. I don't talk about insults in forums.


    So I will rephrase: The terms personal attack and ad hominem are not synonyms, which should be clear from the definition you provided.

    That I provided? Here is what I provided. The text states

    Whenever we attack a person instead of his or her argument, we commit a form of the fallacy known as personal attack. Historically, this fallacy has been known as argumentum ad hominem. or an ad hominem for short.

    Short version: A personal attack is historically known as ad hominem.


    It's been historically misused and falsely applied by a great number of online

    How do they misuse it? Can you give me a couple of examples?

  8. To support what many others have said, here is a helpful link.

    I disagree with that quote. Did you take a look at that website?

    ==> The author seems a bit freeky! <=== ad hominem :D


    The text I have, which I take as authoritative on this issue, defines ad hominem as a synonym for personal attack. As the text states

    Whenever we attack a person instead of his or her argument, we commit a form of the fallacy known as personal attack. Historically, this fallacy has been known as argumentum ad hominem. or an ad hominem for short.


    Short version personal attack is historically known as ad hominem.


    It should be noted that "personal attack" isn't just someone attacking a persons character. It has to be an attack on the person instead of their argument.

  9. Is the electromagnetic (field) a field or a dimension or neither?

    It's a field To be more precise its a vector field. In physics a vector field is a vector function of the position vector. That means that for every point in space represented by the position vector R = (x, y, z) you can associate a vector. A scalar field is a scalar function of the position function, i.e. at every point in space you can associate a number. The electric field is a vector field. In relativity the electromagnetic field is a second rank tensor field which is a tensor function of the 4-position X = (ct, x, y, z)


    And what is the difference between a field and a dimension? Does QCD say that photons are like ripples in the electromagnetic dimension/field?

    A field is described above. A dimension is a number which serves to determine uniquely the configuation of a system. E.g the position vector R = (x, y, z) is three dimensional, i.e. it has three dimensions. Each dimension helps to determine a location in space. Each of the components, x, y, z are each a dimension. The 4-position X = (ct, x, y, z) is 4 dimensional, i.e. it has four dimensions. Each dimension serves to determine a point in spacetime.


    I don't know QED so you'll have to get the answer on that from someone else.

  10. Why can't the question related to electrons be answered?

    Sorry qft123. I intended that to show the nature of the wave-particel duality. In principle the double slit experiment doesn't work just for photons. Theoretically you can defract electrons through a double slit too. It's just way too impractical. However, in 1928 Davisson and Germer did a similar experiment whereby electrons were scattered from the surface of nick crystals and a diffraction pattern was formed. The wonderous thing about this is that they discovered this phenomena by an accident. Cool, huh? :P

  11. good evening friends



    i just want to corelate science and religion on subject big bang (as science ) creation (as religion )in this both cases what is common? in religion god creates the universe

    and in science a point before big bang creates the universe .in both case who created god? no answer who created that point ? no answer so i think we are stil searching the


    There is a book about this out there. In the Beginning ... Biblical Creation and Science Nathan Aviezer, KTAV Publishing House, Inc.

  12. I've never spoke of insults on this topic so I don't know where you got that from.


    Anyway, this thread has served its purpose fo me and confirmed that it was an ad hominem. Thank all of you for your opinion. Especially Aethelwulf. :)

  13. LIGHT

    We do know that photons behave like a wave and a particle both, that's what particle wave duality tells us..

    1)So which source of light behave likes a particle and which one like a wave, How do we know that??

    It's not the source which determines what it behaves like, its the circumstanes. Young's Double Slit Experiment is nice way to explain the wave paticle duality. A beam of photons hits a screen where there are two parallel slits, closely spaced together. An array of photon detectors is placed behind the screen. On the array there forms an interference pattern. That's the wave aspect of photons. If the intensity of the beam is decreased so that only one photon hits the screen at the time then the array will detect only one click at a time indicating that only one photon has hit the screen. If we record where the photons land and let the experiement run for a long time then the interference pattern will appear. That's what the wave-particle duality means.


    2)If a particle has larger wavelength it behaves like a wave and the one which has smaller wavelength behaves like a photon?



    3)Photons have momentum, p=hv/c, do wave have some momentum?

    Yes. If L is the wavelength associated with a particle and p its momentum then L = h/p.



    Electrons are present around the nucleus of an atom(we all know that)

    4) Are they present there as particles, standing frequency, clouds or on orbits(which is the least i would prefer) ??

    That can't be answered. Whether a electron is a partical or a wave depends on how you measure it.

  14. My apologies. One such example would be consistently quoting people speaking as authorities outside of their fields of expertise. Like using Kent Hovind as your expert on evolution.

    Are you sure about that? It says "inability to distinguish expertise from mere authority." That means that when I'm given an exepert opinion and an opinon from "mere authority" I should be able to distinguish between the two. I guess I'm wondering what "mere authority" is?


    Speaking as an authority outside their field is no authority at all. I think that's a given.

  15. I believe what they are discussing is what is commonly referred to as the fallacy of argument from authority.

    Thank you for your response. Yea. I know that its referring to argument from authority. I believe that's obvious. And I undestand that not all arguments based on authorities are fallacious. Argument from authority is a valid technique in reasoning. That wasn't the question. I wanted an example of the inability to distinguish expertise from mere authority.

  16. I'm confused here, you say if both of the planets had the same mass and diameter, but I was asking about two different planets of greatly varying mass.

    Oops! Sorry about that. My mistake. :embarass:


    I mean, if it would cause their clocks to be out of sync, wouldn't that follow that their lifespans would also become out of sync?

    Yes. That's true.


    Oh, also, I know what a paradox is, just calling it that because that's the common used term for the situation. :)

    That was directed to whoever is reading this thread, not you.

  17. Hi folks.


    I'm reading the book Practical Logic: An Antidote to Uncritical Thinking - 5th Ed. by Douglas J. Soccio & Vincent E. Barry, Harcourt Brace Collegte Publishers, (1998). I think we could all benefit from studying logic and learning of to construct and present cogent arguements. That's the purpose of this thread, i.e. to discuss critical thinking and its application to scientific dicussions. If not that then I'm hoping to hear about how you folks choose to reason about/present an argument.


    I'm only up to page 47 so far but I love this book. It teaches you how to more efficiently reason out an argument and to more easily to spot logical fallacies, like ad hominems and strawman arguemets. It talks about certain aspects of arguments such as cogency and its qualities such as reasonableness, relevancy and sufficiency. It also talks about critical thinking which it defines as follows

    Critical thinking is the conscious and deliberate scrutiny of cases and arguements to determine whether or not they meet the criteria of reasonableness, relevancy and sufficiency.


    If gives a partial list of characteristics of critical thinking


    1. application of the criteria of reasonableness, relevancy, and sufficiency to all important claims


    2. distinguishing what is important from what is not according regularly reevaluated principles


    3. careful attention to the meaning of terms


    4. balanced use of relevant expertise


    5. unwillingness to accept any claim that is inconsistent with out own carefully anylyzed experience.


    6. careful assessment of motives (or own and others)


    7. respect for conflicting views when they are reasonably defended.


    8. refusla to take legitimate criticism of arguements pesonally.


    9. asking interrelated and relevant questions.


    10. a willingness to be moved by reason


    11. being open to the possibility of error.


    12. willingness to suspend judgement until sufficient evidence is found


    13. objectivity


    Uncritial thinking is characterized by the following


    1. unwillingness to coinsider the possibility of being wrong


    2. confusing arguments with those who advocate them


    3. taking criticism of arguements personally


    4. indifference to evidence


    5. drawing hasty conclusions based on limited personal experience


    6. contempt for those holding conflicting views


    7. fear of contempt for others culture.


    8. impatience with questions


    9. inappropriate dogmatic assertions of absolute certainty


    10. hostility to reaonsable demands for evidence


    11. inability to distinguish expertise from mere authority.


    This last one confuses me. What is an example of "inability to distinguish expertise from mere authority."?



  18. Have you tried physical therapy?

    Yes. I've tried several rounds of physical therapy, a TEMS unit, two surgeries and pain killers. Pain killers was the last resort and they are helping.

  19. First, as the Wikipedia link emphasizes there is not such paradox in the sense of a logical contradiction.

    The term paradox as it is used here is defined as


    a statement that is seemingly contradictory or opposed to common sense and yet is perhaps true


    Say, if a space ship were traveling at close to the speed of light, and it hits a space bug (somehow doesn't splatter it). The bug on the outside of the ship should be affected by the gravity and the gravity's changes on space/time created by the speed, and so it's time frame would be different from what his bug friends are experiencing back at the hive. Say he were to hang out on the windshield for some years, when he is finally carted back to the hive, he should be a different age from the rest of them solely because of the gravity incurred by the mass generated by the high speed.

    There are two sources of aging at play here. This is a compound problem since there is time dilation due to speed and time dilation due to gravity. Both contribute to the aging of the bug, In any casd, yes, his age would be different.


    I mean, without specifically referring to the twin paradox thought experiment, if you were to have one twin living on planet a, and the second twin living on planet B which has several times the mass as planet A, they would age at different rates when finally reuniting, correct

    If the planets were identical in both diameter and mass and each twin was lying on the surface then they'd age at the same rate. The twin on planet a's wristwatch would be running slower compared to twin b but twin b is also in a potential well too and rn faster than if it wasn't on a planet So the effect is that they cancel out leaving no aging. You can also look at this from a symmetry situation. They have to age at the same rate because one is not special over the other.

  20. And now that pmb has provided the link to me and I see the context, it's even clearer that this is not an ad hominem.

    I disagree of course. He attacked me plain and simple rather than either dropping the subject or reasoning it out. That's an ad hominem plain and simple.


    The person in question started that thread, and this is simply a culmination of asking why you were nit-picking on peripheral subjects.

    Nit picking? Ummm .. so what? Telling someone that a particle with rest mass can't go the speed of light and that's why E = mc^2 = mv^2 is wrong isn't doing something wrong in my opion. I was merely makikng a tiny correction. It was never meant to be more than me pointing out a teeny tiny error. He magnified it into something much much more than it should have been.


    There was some rudeness along the way and you can fault him for that, ...

    Yeah. He's well known for that. He even told me that he chooses to be "harsh" (in his words).


    but it looks to me like you got bogged down in minutia about a mistaken vector sign, and a few other things.

    Its a discussion forum. We discuss physics over there. That includes correcing something that is wrong when we see it. There was nothing "bogged down" in that.


    He asked a question, and you start interrogating him and making him defend the very subject he's asking about.

    I believe that you're exagerating now.


    Here's what happened. He asked about operators. At a point he wrote

    Looking again in my chemistry text, I follow the de Broglie conjecture that [tex]E = h \nu = mc^2=mv^2 ...

    This is wrong so I told him it was wrong. He made a small error in notion so I pointed that out to him. He tried to divide a scalar by a vector and suggested he made a mistake. Later on in the thread I figured out how he made that error with mc^2=mv^2 so I pointed it out to him. That's when he got all whiny. There's really nothing more to it than that.


    There was some poor communication all around. Short version is "I asked bout X, and you're grilling me on Y. What gives?"

    He posted an equation which looked bizzare to me. I corrected it. There's nothing more to it than that.


    I'l provide the link to the thread to anyone else who wants to read it. I really didn't want to discuss the subject of that thread. I was only curious about the ad hominem. The moderator there was so adamant that it wasn't an ad hominem that I decided to keep an open mind and get an unbiased opinion on the subject. Hence the purpose of this thread.

  21. A very nice statistic... 646 rep points (the positive way) no... indeed, it does not bother you...





    What a laugh. I bet the idea of banishing such a point system even in the slightest bothers you, psychologically of course.

    I'm glad you mentioned this. I checked my own and it seems that I'm out of the red and into the green. I guess I do like it. :D

  22. Just because you are more intelligent or think you are more intelligent does not give you a free pass to be an arrogant a$*hole.

    That language is forbidden by the forum rules. Please edit it out. Thanks.


    I don't know how you formed that opinion. I've been reading his posts when I have a chance and they seem fine to me. And I talk to him in PM and he seems like a very pleasant person. I can't imagine how you formed that opinion.

  23. As an aside, if some object of any mass was propelling through space, as it's speed increases, it's mass increases. Regardless of the initial question, it would generate it's own gravitational field due to its increased mass, right?

    Right. What actually happens is that the gravitational field that is present in the rest from of the object becomes stronger as the body is moving.


    So, while something inside of the mass might not be affected by the changes, if something were to come into contact with the speeding object, the space/time relevancy would be affected for it, correct?

    Can you explain that in a different way. I'm totally lost.

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