For faster navigation, this Iframe is preloading the Wikiwand page for Opaque context.

Opaque context

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed.Find sources: "Opaque context" – news · newspapers · books · scholar · JSTOR (December 2018) (Learn how and when to remove this message)

An opaque context or referentially opaque context is a linguistic context in which it is not always possible to substitute "co-referential" expressions (expressions referring to the same object) without altering the truth of sentences.[1] The expressions involved are usually grammatically singular terms. So, substitution of co-referential expressions into an opaque context does not always preserve truth. For example, "Lois believes x is a hero" is an opaque context because "Lois believes Superman is a hero" is true while "Lois believes Clark Kent is a hero" is false, even though 'Superman' and 'Clark Kent' are co-referential expressions.


The term is used in philosophical theories of reference, and is to be contrasted with referentially transparent context. In rough outline:

  • Opacity: "Mary believes that Cicero is a great orator" gives rise to an opaque context; although Cicero was also called 'Tully',[2] we can't simply substitute 'Tully' for 'Cicero' in this context ("Mary believes that Tully is a great orator") and guarantee the same truth value, for Mary might not know that the names 'Tully' and 'Cicero' refer to one and the same thing. Of course, if Mary does believe that Cicero is a great orator, then there is a sense in which Mary believes that Tully is a great orator, even if she does not know that 'Tully' and 'Cicero' corefer. It is the sense forced on us by "direct reference" theories of proper names, i.e. those that maintain that the meaning of a proper name just is its referent.
  • Transparency: "Cicero was a Roman orator" gives rise to a transparent context; there is no problem substituting 'Tully' for 'Cicero' here: "Tully was a Roman orator". Both sentences necessarily express the same thing if 'Cicero' and 'Tully' refer to the same person. Note that this element is missing in the opaque contexts, where a shift in the name can result in a sentence that expresses something different from the original.

Similar usage of the term applies for artificial languages such as programming languages and logics. The Cicero–Tully example above can be easily adapted. Use the notation as a quotation that mentions a term . Define a predicate which is true for terms six letters long. Then induces an opaque context, or is referentially opaque, because is true while is false. Programming languages often have richer semantics than logics' semantics of truth and falsity, and so an operator such as may fail to be referentially transparent for other reasons as well.

See also


  1. ^ "Definition of "opaque context" | Collins English Dictionary". Retrieved 2015-09-29.
  2. ^ Tully is anglicised historic name from Tullius, source: Kearns, Kate. Semantics. p. 145. ISBN 978-0-230-23229-7.
{{bottomLinkPreText}} {{bottomLinkText}}
Opaque context
Listen to this article

This browser is not supported by Wikiwand :(
Wikiwand requires a browser with modern capabilities in order to provide you with the best reading experience.
Please download and use one of the following browsers:

This article was just edited, click to reload
This article has been deleted on Wikipedia (Why?)

Back to homepage

Please click Add in the dialog above
Please click Allow in the top-left corner,
then click Install Now in the dialog
Please click Open in the download dialog,
then click Install
Please click the "Downloads" icon in the Safari toolbar, open the first download in the list,
then click Install

Install Wikiwand

Install on Chrome Install on Firefox
Don't forget to rate us

Tell your friends about Wikiwand!

Gmail Facebook Twitter Link

Enjoying Wikiwand?

Tell your friends and spread the love:
Share on Gmail Share on Facebook Share on Twitter Share on Buffer

Our magic isn't perfect

You can help our automatic cover photo selection by reporting an unsuitable photo.

This photo is visually disturbing This photo is not a good choice

Thank you for helping!

Your input will affect cover photo selection, along with input from other users.


Get ready for Wikiwand 2.0 🎉! the new version arrives on September 1st! Don't want to wait?