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Fallacies: Fallacy of Composition

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