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Fallacies: Fallacy of Composition

In this video, Paul Henne describes the fallacy of composition, an informal fallacy that arises when we assume that some whole has the same properties as its parts. He also discusses why there aren't colorless cats.

Speaker: Paul Henne, Duke University.
Created by Gaurav Vazirani.

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  • male robot hal style avatar for user Yisrael F
    Don't mind my asking, but how is this philosophy?
    (14 votes)
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    • duskpin ultimate style avatar for user okdewit
      Logic is one of the main branches of philosophy, and it's a great one to start with.

      Philosophy is bound to rules, just like any other science. You could philosophize "the universe is purple, because strawberries minus 4", but it would be hard to debate the truth of that statement, because you wouldn't even know how to interpret it.

      Philosophy needs logic, and arguments need to be as fallacy-free as possible to get to the truth.
      (19 votes)
  • male robot johnny style avatar for user Arunlal
    Plain glass is made up of atoms
    atoms are colorless
    therefore plain glass is colorless

    Is the above argument Fallacious ?
    (5 votes)
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    • piceratops seedling style avatar for user tom.chatfield
      Yes, because the statement "atoms are colorless" is largely untrue, thanks to what is essentially a category error: "color" does not apply to tiny, tiny atoms in the same way as it applies to large collections of molecules like glass.

      See some nice detail http://www.fnal.gov/pub/science/inquiring/questions/colorofatoms.html

      There's also a larger problem with this form of argument, which is the (fallacious) assumption that the properties of the parts of something analysed at any scale will necessarily apply identically to the whole. Compare:

      I am made out of atoms
      Atoms are not conscious
      Therefore I am not conscious

      In fact, as we see everywhere, differences of scale bring profound differences of properties. Compare also:

      Everest is made out of tiny pieces of rock
      Tiny pieces of rock are light
      Therefore Everest is light
      (11 votes)
  • leaf green style avatar for user Aways
    does this happen when some people for example see a Frenchman acting politely that all french are polite ?
    (5 votes)
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  • aqualine ultimate style avatar for user Flanny
    I don't follow the reasoning from onwards. Are atoms really colourless? Take spectroscopy, for instance, how can that work if atoms are colourless?
    (2 votes)
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  • leafers ultimate style avatar for user Florence Tsang
    Why is this not a formal fallacy? Can't we say that there's a defect in the form of the argument 'P1: The parts of the whole A have qualities X, Y and Z. C: Therefore, whole A must have qualities X, Y and Z'?
    (2 votes)
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    • leaf green style avatar for user Agent Smith
      This is not a formal fallacy because the error lies in the content of the argument.
      Sometimes the form is valid, sometimes it is invalid. It depends on the content of the argument. Consider the following:

      Each student occupies space
      Therefore, the whole class occupies space.
      The argument above is valid because the property (occupies space) is transferable from the individual members to the whole group.

      Each student has eyes
      Therefore the class has eyes.
      The above argument is fallacious because the property (having eyes) is not transferable from the individual members to the whole.

      So you see, the form is valid sometimes and invalid times but not because of the form of the argument itself but because of the content of the argument.
      (3 votes)
  • blobby green style avatar for user J.S.C.
    I'm confused as to why this is a informal fallacy. Isn't the problem with the form?
    A has B as one of its parts
    B has quality Y
    Therefore A also has quality Y
    (2 votes)
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    • leaf green style avatar for user Agent Smith
      You have rightly seen that such an argument does have a form. However, this form can be fallacious or valid depending on the content of the argument. Therefore it is an informal fallacy.
      Have a look at the following classic examples
      Atoms are invisible
      Statue of liberty is made of atoms
      Therefore, the statue of liberty is invisible
      The fault in the above problem is that the property of the parts is not transferable to the whole
      Look at the following example
      Atoms have mass
      Statue of liberty is made of atoms
      Therefore the statue of liberty has mass
      This argument is not fallacious because the property of the parts is indeed transferable to the whole.

      The point is the form that you have described is valid if the property under consideration is transferable from the parts to the whole and invalid if it is not.
      (3 votes)
  • hopper jumping style avatar for user Lucas De Oliveira
    If in the place of the proposition "every part of a cat is composed of matter, then the whole cat is composed of matter", we have, on the other hand, the sentence: some parts of a cat are composed of matter, then only from it It is not possible to conclude that the whole cat is composed of matter, right?
    (2 votes)
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    • leaf green style avatar for user kubleeka
      It is true that every part of a cat is composed of matter. It is also true that the whole cat is composed of matter. However, we could not determine the truth of the statement "the whole cat is composed of matter" solely based on the fact "every part of the cat is composed of matter."
      (2 votes)
  • piceratops seed style avatar for user Michael Foley
    If you argue that skyscrapers are not visible to the naked eye because skyscrapers are made up of atoms and atoms are not visible to the naked eye, have you committed the informal fallacy of composition?
    (2 votes)
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  • duskpin ultimate style avatar for user tuannb1997
    So, the whole has all the qualitites possessed by it's parts AS LONG AS it is guaranteed that EVERY part of the whole possesses those similar qualities, isn't it ?
    (2 votes)
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  • primosaur seedling style avatar for user Maruti Shukla
    his style of teaching is super good
    he also is good at drawing
    (2 votes)
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Video transcript

(Intro music) Hello, I'm Paul Henne and I'm a philosophy graduate student at Duke University. And in this video I'm gonna talk to you about a particular informal fallacy called the fallacy of composition. In doing this, I'm also going to tell you why we sometimes can't conclude[br]that there are colorless cats. But I'll get to that idea in a second. To recall, an informal fallacy is an argument whose premises[br]do not support its conclusion. Generally, a fallacy is[br]a defect in reasoning. And there are two types of[br]fallacies: formal and informal. A formal fallacy is an[br]argument with an error in the form of the argument and an informal fallacy contains an error in the content of the argument. But you can learn more[br]about this distinction in the video about informal[br]and formal fallacies, which should be out soon. For this video, we're going to focus on a particular informal fallacy. So, the fallacy of composition[br]is an error in reasoning that arises in the content of an argument. People commit this error[br]when they draw conclusions about the whole from truths[br]about its constituent parts, without having a[br]justification for doing so. That is, they think without justification that what is true of[br]the parts of something must also be true of the whole those parts compose. Sounds problematic, right? But let's represent this[br]logical error more formally. The reasoning would be[br]something like this. Premise one: The parts of whole A have qualities X, Y, and Z. Conclusion one: Therefore, whole A must have qualities X, Y, and Z. The argument seems[br]attractive, but the style of argument is like saying that because the states[br]have some set of qualities, then the entire nation[br]must have those qualities. You may now be able to see what's wrong with this line of reasoning. Without sufficient justification, we cannot infer that the[br]whole has the same qualities as its parts simply because[br]the parts have that quality. It may be the case that the[br]whole lacks the qualities that the parts have. It's like saying that because[br]Arizona has an arid climate, the entire nation has an arid climate too. Let's look at a few more examples. It's true that the number three and the number seven are both odd numbers. We might say that three and seven have the characteristic of being odd. Each is also a part of the number ten. Three plus seven equals ten. But we cannot say that the number ten is odd simply because its[br]parts, three and seven, have that quality. If we did, we would commit[br]the fallacy of composition. Let's try another example. Suppose your friend made this argument. Premise one: Atoms are colorless. Premise two: Cats, we know, are[br]composed of a bunch of atoms. Conclusion: Therefore,[br]cats are colorless too. Well, we know that cats[br]are not in fact colorless but we can also see where[br]this person made her error. Without justification,[br]she assumed that the whole has the same qualities as its parts. So, even though the premises[br]of her argument are true she committed the fallacy of composition. So, we don't have to worry[br]about any colorless cats. So, we just learned about[br]the fallacy of composition, or the error in reasoning that comes about when one infers that the[br]whole has the same qualities as its constituent parts. It is important, however, to note that this style of reasoning doesn't always lead to false conclusions. You friend, for instance,[br]might argue the following. Premise one: Every part of[br]my cat is composed of matter. Conclusion: Therefore, my[br]cat is composed of matter. And her argument leads[br]to a true conclusion. The fallacy only arises when we don't have a good reason to infer that the whole has the same qualities as its parts. So, remember to stay[br]vigilant of this fallacy and not to worry about any colorless cats. Subtitles by the Amara.org community