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An "idea" is not copyrightable, only its expression is. "Bad faith" is an idea that is as old as time, that Satre "popularized," but did not invent. What is attributable to him is an exposition ...
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#3: Attribution notice added
Source: https://writers.stackexchange.com/a/23823 License name: CC BY-SA 3.0 License URL: https://creativecommons.org/licenses/by-sa/3.0/
#2: Initial revision
An "idea" is not copyrightable, only its _expression_ is. "Bad faith" is an idea that is as old as time, that Satre "popularized," but did not invent. What is attributable to him is an exposition of what constitutes "bad faith (say a paragraph or longer). _That_ would be copyrightable. That you would cite and attribute to him (and get permission to use). But as long as you use "brief" passages from Satre (a few words or short phrases) and not long sentences or paragraphs, you're ok. For this kind of "use," you don't need to cited sources, because Satre also had his sources,