What is the difference between duality and dichotomy?

They sound very much alike to me, but there is a subtle difference between them. I'm not sure what this difference is, however.

  • Frankly, this is a simple look-up in any dictionary. Questions are supposed to contain minimum research and not be, usually, completely open ended.
    – Lambie
    Feb 8, 2019 at 17:57

2 Answers 2


A "dichotomy" splits a category into two subcategories. A "false dichotomy" is a logical error that incorrectly asserts that something must be in one category or the other; it claims the thing cannot be both or partway in between.

A "duality" describes two aspects of a single thing. For example, applying the "wave-particle duality" principle to light says that for some purposes, a small enough amount of light behaves like a particle; and for other purposes, it behaves like a wave.

  • Can duality be used to mean duplicity. Since it duality means to be dual. And duplicity means to be dual faced?
    – user88834
    Feb 8, 2019 at 7:12
  • "Two-faced" and "snake-tongued" are much better synonyms for "duplicity" than "duality". "Duality" usually refers to complementary things (such as the two monarchies of Sparta, or the Austrian and Hungarian halves of the Austro-Hungarian empire), not to opposite things.
    – Jasper
    Feb 8, 2019 at 7:25
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    @StewartGilliganGriffin: Stack Exchange explicitly encourages you to write an answer to your own question if you have figure out an answer to your own question. In fact, it is even encouraged to post a question with the sole intent of answering it yourself (there is even an answer box right underneath the question box so that you can post both at the same time). Like always, do make sure that you follow all the rules, though. Feb 8, 2019 at 8:44
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    @StewartGilliganGriffin And you could use good and evil as either a dichotomy or a duality, but the intended meaning would change depending on which word you use. If you use it as a dichotomy, you would be arguing "There are good things, and there are evil things." If you use it as a duality, you would be saying something like "There can't be good without evil, and there can't be evil without good."
    – Cort Ammon
    Feb 8, 2019 at 18:06
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    I think this answer defines dichotomy and duality as different and opposing. To use the example, a "wave-particle dichotomy" theory would say that light can either be a wave or a particle, but never both at the same time, while "wave-particle duality" says light can behave like a wave and a particle at the same time, depending on how you look at it. Jul 10, 2020 at 10:03

Unlike dichotomy ,duality can be used with both complementary and opposite things. For example:

The duality of worshipping Aphrodite with Adonis

whereas a dichotomy is always the division of a whole into two things that are contradictory.

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